RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
I tested below combos of qemu and kernel,
++-+-+
|kernel | QEMU | migration |
++-+-+
| SLES11SP2+kvm-kmod-3.6 | qemu-1.6.0|GOOD |
++-+-+
| SLES11SP2+kvm-kmod-3.6 | qemu-1.6.0* |BAD |
++-+-+
| SLES11SP2+kvm-kmod-3.6 | qemu-1.5.1|BAD |
++-+-+
| SLES11SP2+kvm-kmod-3.6*| qemu-1.5.1|GOOD |
++-+-+
| SLES11SP2+kvm-kmod-3.6 | qemu-1.5.1* |GOOD |
++-+-+
| SLES11SP2+kvm-kmod-3.6 | qemu-1.5.2|BAD |
++-+-+
| kvm-3.11-2 | qemu-1.5.1|BAD |
++-+-+
NOTE:
1. kvm-3.11-2 : the whole tag kernel downloaded from
https://git.kernel.org/pub/scm/virt/kvm/kvm.git
2. SLES11SP2+kvm-kmod-3.6 : our release kernel, replace the SLES11SP2's default
kvm-kmod with kvm-kmod-3.6, SLES11SP2's kernel version is 3.0.13-0.27
3. qemu-1.6.0* : revert the commit 211ea74022f51164a7729030b28eec90b6c99a08 on
qemu-1.6.0
4. kvm-kmod-3.6* : kvm-kmod-3.6 with EPT disabled
5. qemu-1.5.1* : apply below patch to qemu-1.5.1 to delete qemu_madvise()
statement in ram_load() function
--- qemu-1.5.1/arch_init.c 2013-06-27 05:47:29.0 +0800
+++ qemu-1.5.1_fix3/arch_init.c 2013-08-28 19:43:42.0 +0800
@@ -842,7 +842,6 @@ static int ram_load(QEMUFile *f, void *o
if (ch == 0 &&
(!kvm_enabled() || kvm_has_sync_mmu()) &&
getpagesize() <= TARGET_PAGE_SIZE) {
-qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
}
#endif
} else if (flags & RAM_SAVE_FLAG_PAGE) {
If I apply above patch to qemu-1.5.1 to delete the qemu_madvise() statement,
the test result of the combos of SLES11SP2+kvm-kmod-3.6 and qemu-1.5.1 is good.
Why do we perform the qemu_madvise(QEMU_MADV_DONTNEED) for those zero pages?
Does the qemu_madvise() have sustained effect on the range of virtual address?
In other words, does qemu_madvise() have sustained effect on the VM performance?
If later frequently read/write the range of virtual address which have been
advised to DONTNEED, could performance degradation happen?
The reason why the combos of SLES11SP2+kvm-kmod-3.6 and qemu-1.6.0 is good, is
because of commit 211ea74022f51164a7729030b28eec90b6c99a08,
if I revert the commit 211ea74022f51164a7729030b28eec90b6c99a08 on qemu-1.6.0,
the test result of combos of SLES11SP2+kvm-kmod-3.6 and qemu-1.6.0 is bad,
performance degradation happened, too.
Thanks,
Zhang Haoyu
>> >>> The QEMU command line (/var/log/libvirt/qemu/[domain name].log),
>> >>> LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/
>> >>> QEMU_AUDIO_DRV=none
>> >>> /usr/local/bin/qemu-system-x86_64 -name ATS1 -S -M pc-0.12 -cpu
>> >>> qemu32 -enable-kvm -m 12288 -smp 4,sockets=4,cores=1,threads=1
>> >>> -uuid
>> >>> 0505ec91-382d-800e-2c79-e5b286eb60b5 -no-user-config -nodefaults
>> >>> -chardev
>> >>> socket,id=charmonitor,path=/var/lib/libvirt/qemu/ATS1.monitor,serv
>> >>> er, n owait -mon chardev=charmonitor,id=monitor,mode=control -rtc
>> >>> base=localtime -no-shutdown -device
>> >>> piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive
>> >>> file=/opt/ne/vm/ATS1.img,if=none,id=drive-virtio-disk0,format=raw,
>> >>> cac
>> >>> h
>> >>> e=none -device
>> >>> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk
>> >>> 0,i
>> >>> d
>> >>> =virtio-disk0,bootindex=1 -netdev
>> >>> tap,fd=20,id=hostnet0,vhost=on,vhostfd=21 -device
>> >>> virtio-net-pci,netdev=hostnet0,id=net0,mac=00:e0:fc:00:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x3,bootindex=2 -netdev
>> >>> tap,fd=22,id=hostnet1,vhost=on,vhostfd=23 -device
>> >>> virtio-net-pci,netdev=hostnet1,id=net1,mac=00:e0:fc:01:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x4 -netdev tap,fd=24,id=hostnet2,vhost=on,vhostfd=25
>> >>> -device
>> >>> virtio-net-pci,netdev=hostnet2,id=net2,mac=00:e0:fc:02:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x5 -netdev tap,fd=26,id=hostnet3,vhost=on,vhostfd=27
>> >>> -device
>> >>> virtio-net-pci,netdev=hostnet3,id=net3,mac=00:e0:fc:03:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x6 -netdev tap,fd=28,id=hostnet4,vhost=on,vhostfd=29
>> >>> -device
>> >>> virtio-net-pci,netdev=hostnet4,id=net4,mac=00:e0:fc:0a:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x7 -netdev tap,fd=30,id=hostnet5,vhost=on,vhostfd=31
>> >>> -device
>> >>> virtio-net-pci,netdev=hostnet5,id=net5,mac=00:e0:fc:0b:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x9 -chardev pty,id=charserial0 -device
>> >>> isa-serial,chardev=charserial0,id=serial0 -vnc *:0 -k en-us -vga
>> >>> cirrus -device i6300es
RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
>>> >>> The QEMU command line (/var/log/libvirt/qemu/[domain name].log), >>> >>> LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/ >>> >>> QEMU_AUDIO_DRV=none >>> >>> /usr/local/bin/qemu-system-x86_64 -name ATS1 -S -M pc-0.12 -cpu >>> >>> qemu32 -enable-kvm -m 12288 -smp 4,sockets=4,cores=1,threads=1 >>> >>> -uuid >>> >>> 0505ec91-382d-800e-2c79-e5b286eb60b5 -no-user-config -nodefaults >>> >>> -chardev >>> >>> socket,id=charmonitor,path=/var/lib/libvirt/qemu/ATS1.monitor,ser >>> >>> ver, n owait -mon chardev=charmonitor,id=monitor,mode=control >>> >>> -rtc base=localtime -no-shutdown -device >>> >>> piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive >>> >>> file=/opt/ne/vm/ATS1.img,if=none,id=drive-virtio-disk0,format=raw >>> >>> ,cac >>> >>> h >>> >>> e=none -device >>> >>> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-dis >>> >>> k0,i >>> >>> d >>> >>> =virtio-disk0,bootindex=1 -netdev >>> >>> tap,fd=20,id=hostnet0,vhost=on,vhostfd=21 -device >>> >>> virtio-net-pci,netdev=hostnet0,id=net0,mac=00:e0:fc:00:0f:00,bus=pci. >>> >>> 0 >>> >>> ,addr=0x3,bootindex=2 -netdev >>> >>> tap,fd=22,id=hostnet1,vhost=on,vhostfd=23 -device >>> >>> virtio-net-pci,netdev=hostnet1,id=net1,mac=00:e0:fc:01:0f:00,bus=pci. >>> >>> 0 >>> >>> ,addr=0x4 -netdev tap,fd=24,id=hostnet2,vhost=on,vhostfd=25 >>> >>> -device >>> >>> virtio-net-pci,netdev=hostnet2,id=net2,mac=00:e0:fc:02:0f:00,bus=pci. >>> >>> 0 >>> >>> ,addr=0x5 -netdev tap,fd=26,id=hostnet3,vhost=on,vhostfd=27 >>> >>> -device >>> >>> virtio-net-pci,netdev=hostnet3,id=net3,mac=00:e0:fc:03:0f:00,bus=pci. >>> >>> 0 >>> >>> ,addr=0x6 -netdev tap,fd=28,id=hostnet4,vhost=on,vhostfd=29 >>> >>> -device >>> >>> virtio-net-pci,netdev=hostnet4,id=net4,mac=00:e0:fc:0a:0f:00,bus=pci. >>> >>> 0 >>> >>> ,addr=0x7 -netdev tap,fd=30,id=hostnet5,vhost=on,vhostfd=31 >>> >>> -device >>> >>> virtio-net-pci,netdev=hostnet5,id=net5,mac=00:e0:fc:0b:0f:00,bus=pci. >>> >>> 0 >>> >>> ,addr=0x9 -chardev pty,id=charserial0 -device >>> >>> isa-serial,chardev=charserial0,id=serial0 -vnc *:0 -k en-us -vga >>> >>> cirrus -device i6300esb,id=watchdog0,bus=pci.0,addr=0xb >>> >>> -watchdog-action poweroff -device >>> >>> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0xa >>> >>> >>> >>Which QEMU version is this? Can you try with e1000 NICs instead of virtio? >>> >> >>> >This QEMU version is 1.0.0, but I also test QEMU 1.5.2, the same problem >>> >exists, including the performance degradation and readonly GFNs' flooding. >>> >I tried with e1000 NICs instead of virtio, including the performance >>> >degradation and readonly GFNs' flooding, the QEMU version is 1.5.2. >>> >No matter e1000 NICs or virtio NICs, the GFNs' flooding is initiated at >>> >post-restore stage (i.e. running stage), as soon as the restoring >>> >completed, the flooding is starting. >>> > >>> >Thanks, >>> >Zhang Haoyu >>> > >>> >>-- >>> >> Gleb. >>> >>> Should we focus on the first bad >>> commit(612819c3c6e67bac8fceaa7cc402f13b1b63f7e4) and the surprising GFNs' >>> flooding? >>> >>Not really. There is no point in debugging very old version compiled >>with kvm-kmod, there are to many variables in the environment. I cannot >>reproduce the GFN flooding on upstream, so the problem may be gone, may >>be a result of kvm-kmod problem or something different in how I invoke >>qemu. So the best way to proceed is for you to reproduce with upstream >>version then at least I will be sure that we are using the same code. >> >Thanks, I will test the combos of upstream kvm kernel and upstream qemu. >And, the guest os version above I said was wrong, current running guest os is >SLES10SP4. > I tested below combos of qemu and kernel, +-+-+-+ | kvm kernel | QEMU | test result | +-+-+-+ | kvm-3.11-2 | qemu-1.5.2| GOOD | +-+-+-+ | SLES11SP2 | qemu-1.0.0| BAD| +-+-+-+ | SLES11SP2 | qemu-1.4.0| BAD| +-+-+-+ | SLES11SP2 | qemu-1.4.2| BAD| +-+-+-+ | SLES11SP2 | qemu-1.5.0-rc0 | GOOD | +-+-+-+ | SLES11SP2 | qemu-1.5.0| GOOD | +-+-+-+ | SLES11SP2 | qemu-1.5.1| GOOD | +-+-+-+ | SLES11SP2 | qemu-1.5.2| GOOD | +-+-+-+ NOTE: 1. above kvm-3.11-2 in the table is the whole tag kernel download from https://git.kernel.org/pub/scm/virt/kvm/kvm.git 2. SLES11SP2's kernel version is 3.0.13-0.27 Then I git bisect the qemu changes between
RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
>> >>> The QEMU command line (/var/log/libvirt/qemu/[domain name].log),
>> >>> LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/
>> >>> QEMU_AUDIO_DRV=none
>> >>> /usr/local/bin/qemu-system-x86_64 -name ATS1 -S -M pc-0.12 -cpu
>> >>> qemu32 -enable-kvm -m 12288 -smp 4,sockets=4,cores=1,threads=1 -uuid
>> >>> 0505ec91-382d-800e-2c79-e5b286eb60b5 -no-user-config -nodefaults
>> >>> -chardev
>> >>> socket,id=charmonitor,path=/var/lib/libvirt/qemu/ATS1.monitor,server,
>> >>> n owait -mon chardev=charmonitor,id=monitor,mode=control -rtc
>> >>> base=localtime -no-shutdown -device
>> >>> piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive
>> >>> file=/opt/ne/vm/ATS1.img,if=none,id=drive-virtio-disk0,format=raw,cac
>> >>> h
>> >>> e=none -device
>> >>> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk0,i
>> >>> d
>> >>> =virtio-disk0,bootindex=1 -netdev
>> >>> tap,fd=20,id=hostnet0,vhost=on,vhostfd=21 -device
>> >>> virtio-net-pci,netdev=hostnet0,id=net0,mac=00:e0:fc:00:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x3,bootindex=2 -netdev
>> >>> tap,fd=22,id=hostnet1,vhost=on,vhostfd=23 -device
>> >>> virtio-net-pci,netdev=hostnet1,id=net1,mac=00:e0:fc:01:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x4 -netdev tap,fd=24,id=hostnet2,vhost=on,vhostfd=25 -device
>> >>> virtio-net-pci,netdev=hostnet2,id=net2,mac=00:e0:fc:02:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x5 -netdev tap,fd=26,id=hostnet3,vhost=on,vhostfd=27 -device
>> >>> virtio-net-pci,netdev=hostnet3,id=net3,mac=00:e0:fc:03:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x6 -netdev tap,fd=28,id=hostnet4,vhost=on,vhostfd=29 -device
>> >>> virtio-net-pci,netdev=hostnet4,id=net4,mac=00:e0:fc:0a:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x7 -netdev tap,fd=30,id=hostnet5,vhost=on,vhostfd=31 -device
>> >>> virtio-net-pci,netdev=hostnet5,id=net5,mac=00:e0:fc:0b:0f:00,bus=pci.
>> >>> 0
>> >>> ,addr=0x9 -chardev pty,id=charserial0 -device
>> >>> isa-serial,chardev=charserial0,id=serial0 -vnc *:0 -k en-us -vga
>> >>> cirrus -device i6300esb,id=watchdog0,bus=pci.0,addr=0xb
>> >>> -watchdog-action poweroff -device
>> >>> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0xa
>> >>>
>> >>Which QEMU version is this? Can you try with e1000 NICs instead of virtio?
>> >>
>> >This QEMU version is 1.0.0, but I also test QEMU 1.5.2, the same problem
>> >exists, including the performance degradation and readonly GFNs' flooding.
>> >I tried with e1000 NICs instead of virtio, including the performance
>> >degradation and readonly GFNs' flooding, the QEMU version is 1.5.2.
>> >No matter e1000 NICs or virtio NICs, the GFNs' flooding is initiated at
>> >post-restore stage (i.e. running stage), as soon as the restoring
>> >completed, the flooding is starting.
>> >
>> >Thanks,
>> >Zhang Haoyu
>> >
>> >>--
>> >> Gleb.
>>
>> Should we focus on the first bad
>> commit(612819c3c6e67bac8fceaa7cc402f13b1b63f7e4) and the surprising GFNs'
>> flooding?
>>
>Not really. There is no point in debugging very old version compiled
>with kvm-kmod, there are to many variables in the environment. I cannot
>reproduce the GFN flooding on upstream, so the problem may be gone, may
>be a result of kvm-kmod problem or something different in how I invoke
>qemu. So the best way to proceed is for you to reproduce with upstream
>version then at least I will be sure that we are using the same code.
>
Thanks, I will test the combos of upstream kvm kernel and upstream qemu.
And, the guest os version above I said was wrong, current running guest os is
SLES10SP4.
Thanks,
Zhang Haoyu
>> I applied below patch to __direct_map(),
>> @@ -2223,6 +2223,8 @@ static int __direct_map(struct kvm_vcpu
>> int pt_write = 0;
>> gfn_t pseudo_gfn;
>>
>> +map_writable = true;
>> +
>> for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
>> if (iterator.level == level) {
>> unsigned pte_access = ACC_ALL;
>> and rebuild the kvm-kmod, then re-insmod it.
>> After I started a VM, the host seemed to be abnormal, so many programs
>> cannot be started successfully, segmentation fault is reported.
>> In my opinion, after above patch applied, the commit:
>> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4 should be of no effect, but the
>> test result proved me wrong.
>> Dose the map_writable value's getting process in hva_to_pfn() have effect on
>> the result?
>>
>If hva_to_pfn() returns map_writable == false it means that page is
>mapped as read only on primary MMU, so it should not be mapped writable
>on secondary MMU either. This should not happen usually.
>
>--
> Gleb.
Re: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
On Wed, Aug 07, 2013 at 01:34:41AM +, Zhanghaoyu (A) wrote:
> >>> The QEMU command line (/var/log/libvirt/qemu/[domain name].log),
> >>> LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/
> >>> QEMU_AUDIO_DRV=none
> >>> /usr/local/bin/qemu-system-x86_64 -name ATS1 -S -M pc-0.12 -cpu
> >>> qemu32 -enable-kvm -m 12288 -smp 4,sockets=4,cores=1,threads=1 -uuid
> >>> 0505ec91-382d-800e-2c79-e5b286eb60b5 -no-user-config -nodefaults
> >>> -chardev
> >>> socket,id=charmonitor,path=/var/lib/libvirt/qemu/ATS1.monitor,server,
> >>> n owait -mon chardev=charmonitor,id=monitor,mode=control -rtc
> >>> base=localtime -no-shutdown -device
> >>> piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive
> >>> file=/opt/ne/vm/ATS1.img,if=none,id=drive-virtio-disk0,format=raw,cac
> >>> h
> >>> e=none -device
> >>> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk0,i
> >>> d
> >>> =virtio-disk0,bootindex=1 -netdev
> >>> tap,fd=20,id=hostnet0,vhost=on,vhostfd=21 -device
> >>> virtio-net-pci,netdev=hostnet0,id=net0,mac=00:e0:fc:00:0f:00,bus=pci.
> >>> 0
> >>> ,addr=0x3,bootindex=2 -netdev
> >>> tap,fd=22,id=hostnet1,vhost=on,vhostfd=23 -device
> >>> virtio-net-pci,netdev=hostnet1,id=net1,mac=00:e0:fc:01:0f:00,bus=pci.
> >>> 0
> >>> ,addr=0x4 -netdev tap,fd=24,id=hostnet2,vhost=on,vhostfd=25 -device
> >>> virtio-net-pci,netdev=hostnet2,id=net2,mac=00:e0:fc:02:0f:00,bus=pci.
> >>> 0
> >>> ,addr=0x5 -netdev tap,fd=26,id=hostnet3,vhost=on,vhostfd=27 -device
> >>> virtio-net-pci,netdev=hostnet3,id=net3,mac=00:e0:fc:03:0f:00,bus=pci.
> >>> 0
> >>> ,addr=0x6 -netdev tap,fd=28,id=hostnet4,vhost=on,vhostfd=29 -device
> >>> virtio-net-pci,netdev=hostnet4,id=net4,mac=00:e0:fc:0a:0f:00,bus=pci.
> >>> 0
> >>> ,addr=0x7 -netdev tap,fd=30,id=hostnet5,vhost=on,vhostfd=31 -device
> >>> virtio-net-pci,netdev=hostnet5,id=net5,mac=00:e0:fc:0b:0f:00,bus=pci.
> >>> 0
> >>> ,addr=0x9 -chardev pty,id=charserial0 -device
> >>> isa-serial,chardev=charserial0,id=serial0 -vnc *:0 -k en-us -vga
> >>> cirrus -device i6300esb,id=watchdog0,bus=pci.0,addr=0xb
> >>> -watchdog-action poweroff -device
> >>> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0xa
> >>>
> >>Which QEMU version is this? Can you try with e1000 NICs instead of virtio?
> >>
> >This QEMU version is 1.0.0, but I also test QEMU 1.5.2, the same problem
> >exists, including the performance degradation and readonly GFNs' flooding.
> >I tried with e1000 NICs instead of virtio, including the performance
> >degradation and readonly GFNs' flooding, the QEMU version is 1.5.2.
> >No matter e1000 NICs or virtio NICs, the GFNs' flooding is initiated at
> >post-restore stage (i.e. running stage), as soon as the restoring completed,
> >the flooding is starting.
> >
> >Thanks,
> >Zhang Haoyu
> >
> >>--
> >>Gleb.
>
> Should we focus on the first bad
> commit(612819c3c6e67bac8fceaa7cc402f13b1b63f7e4) and the surprising GFNs'
> flooding?
>
Not really. There is no point in debugging very old version compiled
with kvm-kmod, there are to many variables in the environment. I cannot
reproduce the GFN flooding on upstream, so the problem may be gone, may
be a result of kvm-kmod problem or something different in how I invoke
qemu. So the best way to proceed is for you to reproduce with upstream
version then at least I will be sure that we are using the same code.
> I applied below patch to __direct_map(),
> @@ -2223,6 +2223,8 @@ static int __direct_map(struct kvm_vcpu
> int pt_write = 0;
> gfn_t pseudo_gfn;
>
> +map_writable = true;
> +
> for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
> if (iterator.level == level) {
> unsigned pte_access = ACC_ALL;
> and rebuild the kvm-kmod, then re-insmod it.
> After I started a VM, the host seemed to be abnormal, so many programs cannot
> be started successfully, segmentation fault is reported.
> In my opinion, after above patch applied, the commit:
> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4 should be of no effect, but the test
> result proved me wrong.
> Dose the map_writable value's getting process in hva_to_pfn() have effect on
> the result?
>
If hva_to_pfn() returns map_writable == false it means that page is
mapped as read only on primary MMU, so it should not be mapped writable
on secondary MMU either. This should not happen usually.
--
Gleb.
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RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
>>> The QEMU command line (/var/log/libvirt/qemu/[domain name].log),
>>> LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/
>>> QEMU_AUDIO_DRV=none
>>> /usr/local/bin/qemu-system-x86_64 -name ATS1 -S -M pc-0.12 -cpu
>>> qemu32 -enable-kvm -m 12288 -smp 4,sockets=4,cores=1,threads=1 -uuid
>>> 0505ec91-382d-800e-2c79-e5b286eb60b5 -no-user-config -nodefaults
>>> -chardev
>>> socket,id=charmonitor,path=/var/lib/libvirt/qemu/ATS1.monitor,server,
>>> n owait -mon chardev=charmonitor,id=monitor,mode=control -rtc
>>> base=localtime -no-shutdown -device
>>> piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive
>>> file=/opt/ne/vm/ATS1.img,if=none,id=drive-virtio-disk0,format=raw,cac
>>> h
>>> e=none -device
>>> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk0,i
>>> d
>>> =virtio-disk0,bootindex=1 -netdev
>>> tap,fd=20,id=hostnet0,vhost=on,vhostfd=21 -device
>>> virtio-net-pci,netdev=hostnet0,id=net0,mac=00:e0:fc:00:0f:00,bus=pci.
>>> 0
>>> ,addr=0x3,bootindex=2 -netdev
>>> tap,fd=22,id=hostnet1,vhost=on,vhostfd=23 -device
>>> virtio-net-pci,netdev=hostnet1,id=net1,mac=00:e0:fc:01:0f:00,bus=pci.
>>> 0
>>> ,addr=0x4 -netdev tap,fd=24,id=hostnet2,vhost=on,vhostfd=25 -device
>>> virtio-net-pci,netdev=hostnet2,id=net2,mac=00:e0:fc:02:0f:00,bus=pci.
>>> 0
>>> ,addr=0x5 -netdev tap,fd=26,id=hostnet3,vhost=on,vhostfd=27 -device
>>> virtio-net-pci,netdev=hostnet3,id=net3,mac=00:e0:fc:03:0f:00,bus=pci.
>>> 0
>>> ,addr=0x6 -netdev tap,fd=28,id=hostnet4,vhost=on,vhostfd=29 -device
>>> virtio-net-pci,netdev=hostnet4,id=net4,mac=00:e0:fc:0a:0f:00,bus=pci.
>>> 0
>>> ,addr=0x7 -netdev tap,fd=30,id=hostnet5,vhost=on,vhostfd=31 -device
>>> virtio-net-pci,netdev=hostnet5,id=net5,mac=00:e0:fc:0b:0f:00,bus=pci.
>>> 0
>>> ,addr=0x9 -chardev pty,id=charserial0 -device
>>> isa-serial,chardev=charserial0,id=serial0 -vnc *:0 -k en-us -vga
>>> cirrus -device i6300esb,id=watchdog0,bus=pci.0,addr=0xb
>>> -watchdog-action poweroff -device
>>> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0xa
>>>
>>Which QEMU version is this? Can you try with e1000 NICs instead of virtio?
>>
>This QEMU version is 1.0.0, but I also test QEMU 1.5.2, the same problem
>exists, including the performance degradation and readonly GFNs' flooding.
>I tried with e1000 NICs instead of virtio, including the performance
>degradation and readonly GFNs' flooding, the QEMU version is 1.5.2.
>No matter e1000 NICs or virtio NICs, the GFNs' flooding is initiated at
>post-restore stage (i.e. running stage), as soon as the restoring completed,
>the flooding is starting.
>
>Thanks,
>Zhang Haoyu
>
>>--
>> Gleb.
Should we focus on the first bad
commit(612819c3c6e67bac8fceaa7cc402f13b1b63f7e4) and the surprising GFNs'
flooding?
I applied below patch to __direct_map(),
@@ -2223,6 +2223,8 @@ static int __direct_map(struct kvm_vcpu
int pt_write = 0;
gfn_t pseudo_gfn;
+map_writable = true;
+
for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
if (iterator.level == level) {
unsigned pte_access = ACC_ALL;
and rebuild the kvm-kmod, then re-insmod it.
After I started a VM, the host seemed to be abnormal, so many programs cannot
be started successfully, segmentation fault is reported.
In my opinion, after above patch applied, the commit:
612819c3c6e67bac8fceaa7cc402f13b1b63f7e4 should be of no effect, but the test
result proved me wrong.
Dose the map_writable value's getting process in hva_to_pfn() have effect on
the result?
Thanks,
Zhang Haoyu
--
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the body of a message to majord...@vger.kernel.org
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RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
>> The QEMU command line (/var/log/libvirt/qemu/[domain name].log), >> LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/ QEMU_AUDIO_DRV=none >> /usr/local/bin/qemu-system-x86_64 -name ATS1 -S -M pc-0.12 -cpu qemu32 >> -enable-kvm -m 12288 -smp 4,sockets=4,cores=1,threads=1 -uuid >> 0505ec91-382d-800e-2c79-e5b286eb60b5 -no-user-config -nodefaults >> -chardev >> socket,id=charmonitor,path=/var/lib/libvirt/qemu/ATS1.monitor,server,n >> owait -mon chardev=charmonitor,id=monitor,mode=control -rtc >> base=localtime -no-shutdown -device >> piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive >> file=/opt/ne/vm/ATS1.img,if=none,id=drive-virtio-disk0,format=raw,cach >> e=none -device >> virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk0,id >> =virtio-disk0,bootindex=1 -netdev >> tap,fd=20,id=hostnet0,vhost=on,vhostfd=21 -device >> virtio-net-pci,netdev=hostnet0,id=net0,mac=00:e0:fc:00:0f:00,bus=pci.0 >> ,addr=0x3,bootindex=2 -netdev >> tap,fd=22,id=hostnet1,vhost=on,vhostfd=23 -device >> virtio-net-pci,netdev=hostnet1,id=net1,mac=00:e0:fc:01:0f:00,bus=pci.0 >> ,addr=0x4 -netdev tap,fd=24,id=hostnet2,vhost=on,vhostfd=25 -device >> virtio-net-pci,netdev=hostnet2,id=net2,mac=00:e0:fc:02:0f:00,bus=pci.0 >> ,addr=0x5 -netdev tap,fd=26,id=hostnet3,vhost=on,vhostfd=27 -device >> virtio-net-pci,netdev=hostnet3,id=net3,mac=00:e0:fc:03:0f:00,bus=pci.0 >> ,addr=0x6 -netdev tap,fd=28,id=hostnet4,vhost=on,vhostfd=29 -device >> virtio-net-pci,netdev=hostnet4,id=net4,mac=00:e0:fc:0a:0f:00,bus=pci.0 >> ,addr=0x7 -netdev tap,fd=30,id=hostnet5,vhost=on,vhostfd=31 -device >> virtio-net-pci,netdev=hostnet5,id=net5,mac=00:e0:fc:0b:0f:00,bus=pci.0 >> ,addr=0x9 -chardev pty,id=charserial0 -device >> isa-serial,chardev=charserial0,id=serial0 -vnc *:0 -k en-us -vga >> cirrus -device i6300esb,id=watchdog0,bus=pci.0,addr=0xb >> -watchdog-action poweroff -device >> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0xa >> >Which QEMU version is this? Can you try with e1000 NICs instead of virtio? > This QEMU version is 1.0.0, but I also test QEMU 1.5.2, the same problem exists, including the performance degradation and readonly GFNs' flooding. I tried with e1000 NICs instead of virtio, including the performance degradation and readonly GFNs' flooding, the QEMU version is 1.5.2. No matter e1000 NICs or virtio NICs, the GFNs' flooding is initiated at post-restore stage (i.e. running stage), as soon as the restoring completed, the flooding is starting. Thanks, Zhang Haoyu >-- > Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
On Mon, Aug 05, 2013 at 09:09:56AM +, Zhanghaoyu (A) wrote: > The QEMU command line (/var/log/libvirt/qemu/[domain name].log), > LC_ALL=C PATH=/bin:/sbin:/usr/bin:/usr/sbin HOME=/ QEMU_AUDIO_DRV=none > /usr/local/bin/qemu-system-x86_64 -name ATS1 -S -M pc-0.12 -cpu qemu32 > -enable-kvm -m 12288 -smp 4,sockets=4,cores=1,threads=1 -uuid > 0505ec91-382d-800e-2c79-e5b286eb60b5 -no-user-config -nodefaults -chardev > socket,id=charmonitor,path=/var/lib/libvirt/qemu/ATS1.monitor,server,nowait > -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime > -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive > file=/opt/ne/vm/ATS1.img,if=none,id=drive-virtio-disk0,format=raw,cache=none > -device > virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 > -netdev tap,fd=20,id=hostnet0,vhost=on,vhostfd=21 -device > virtio-net-pci,netdev=hostnet0,id=net0,mac=00:e0:fc:00:0f:00,bus=pci.0,addr=0x3,bootindex=2 > -netdev tap,fd=22,id=hostnet1,vhost=on,vhostfd=23 -device > virtio-net-pci,netdev=hostnet1,id=net1,mac=00:e0:fc:01:0f:00,bus=pci.0,addr=0x4 > -netdev tap,fd=24,id=hostnet2,vhost=on,vhostfd=25 -device > virtio-net-pci,netdev=hostnet2,id=net2,mac=00:e0:fc:02:0f:00,bus=pci.0,addr=0x5 > -netdev tap,fd=26,id=hostnet3,vhost=on,vhostfd=27 -device > virtio-net-pci,netdev=hostnet3,id=net3,mac=00:e0:fc:03:0f:00,bus=pci.0,addr=0x6 > -netdev tap,fd=28,id=hostnet4,vhost=on,vhostfd=29 -device > virtio-net-pci,netdev=hostnet4,id=net4,mac=00:e0:fc:0a:0f:00,bus=pci.0,addr=0x7 > -netdev tap,fd=30,id=hostnet5,vhost=on,vhostfd=31 -device > virtio-net-pci,netdev=hostnet5,id=net5,mac=00:e0:fc:0b:0f:00,bus=pci.0,addr=0x9 > -chardev pty,id=charserial0 -device > isa-serial,chardev=charserial0,id=serial0 -vnc *:0 -k en-us -vga cirrus > -device i6300esb,id=watchdog0,bus=pci.0,addr=0xb -watchdog-action poweroff > -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0xa > Which QEMU version is this? Can you try with e1000 NICs instead of virtio? -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
>Hi,
>
>Am 05.08.2013 11:09, schrieb Zhanghaoyu (A):
>> When I build the upstream, encounter a problem that I compile and
>> install the upstream(commit: e769ece3b129698d2b09811a6f6d304e4eaa8c29)
>> on sles11sp2 environment via below command cp
>> /boot/config-3.0.13-0.27-default ./.config yes "" | make oldconfig
>> make && make modules_install && make install then, I reboot the host,
>> and select the upstream kernel, but during the starting stage, below
>> problem happened, Could not find
>> /dev/disk/by-id/scsi-3600508e0864407c5b8f7ad01-part3
>>
>> I'm trying to resolve it.
>
>Possibly you need to enable loading unsupported kernel modules?
>At least that's needed when testing a kmod with a SUSE kernel.
>
I have tried to set " allow_unsupported_modules 1" in
/etc/modprobe.d/unsupported-modules, but the problem still happened.
I replace the whole kernel with the kvm kernel, not only the kvm modules.
>Regards,
>Andreas
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Re: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
Hi, Am 05.08.2013 11:09, schrieb Zhanghaoyu (A): > When I build the upstream, encounter a problem that I compile and install the > upstream(commit: e769ece3b129698d2b09811a6f6d304e4eaa8c29) on sles11sp2 > environment via below command > cp /boot/config-3.0.13-0.27-default ./.config > yes "" | make oldconfig > make && make modules_install && make install > then, I reboot the host, and select the upstream kernel, but during the > starting stage, below problem happened, > Could not find /dev/disk/by-id/scsi-3600508e0864407c5b8f7ad01-part3 > > I'm trying to resolve it. Possibly you need to enable loading unsupported kernel modules? At least that's needed when testing a kmod with a SUSE kernel. Regards, Andreas -- SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
>> >> >> >> hi all,
>> >> >> >>
>> >> >> >> I met similar problem to these, while performing live migration or
>> >> >> >> save-restore test on the kvm platform (qemu:1.4.0, host:suse11sp2,
>> >> >> >> guest:suse11sp2), running tele-communication software suite in
>> >> >> >> guest,
>> >> >> >> https://lists.gnu.org/archive/html/qemu-devel/2013-05/msg00098.html
>> >> >> >> http://comments.gmane.org/gmane.comp.emulators.kvm.devel/102506
>> >> >> >> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/100592
>> >> >> >> https://bugzilla.kernel.org/show_bug.cgi?id=58771
>> >> >> >>
>> >> >> >> After live migration or virsh restore [savefile], one process's CPU
>> >> >> >> utilization went up by about 30%, resulted in throughput
>> >> >> >> degradation of this process.
>> >> >> >>
>> >> >> >> If EPT disabled, this problem gone.
>> >> >> >>
>> >> >> >> I suspect that kvm hypervisor has business with this problem.
>> >> >> >> Based on above suspect, I want to find the two adjacent versions of
>> >> >> >> kvm-kmod which triggers this problem or not (e.g. 2.6.39, 3.0-rc1),
>> >> >> >> and analyze the differences between this two versions, or apply the
>> >> >> >> patches between this two versions by bisection method, finally find
>> >> >> >> the key patches.
>> >> >> >>
>> >> >> >> Any better ideas?
>> >> >> >>
>> >> >> >> Thanks,
>> >> >> >> Zhang Haoyu
>> >> >> >
>> >> >> >I've attempted to duplicate this on a number of machines that are as
>> >> >> >similar to yours as I am able to get my hands on, and so far have not
>> >> >> >been able to see any performance degradation. And from what I've read
>> >> >> >in the above links, huge pages do not seem to be part of the problem.
>> >> >> >
>> >> >> >So, if you are in a position to bisect the kernel changes, that would
>> >> >> >probably be the best avenue to pursue in my opinion.
>> >> >> >
>> >> >> >Bruce
>> >> >>
>> >> >> I found the first bad
>> >> >> commit([612819c3c6e67bac8fceaa7cc402f13b1b63f7e4] KVM: propagate fault
>> >> >> r/w information to gup(), allow read-only memory) which triggers this
>> >> >> problem by git bisecting the kvm kernel (download from
>> >> >> https://git.kernel.org/pub/scm/virt/kvm/kvm.git) changes.
>> >> >>
>> >> >> And,
>> >> >> git log 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4 -n 1 -p >
>> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.log
>> >> >> git diff
>> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4~1..612819c3c6e67bac8fceaa7cc4
>> >> >> 02f13b1b63f7e4 > 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.diff
>> >> >>
>> >> >> Then, I diffed 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.log and
>> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.diff,
>> >> >> came to a conclusion that all of the differences between
>> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4~1 and
>> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4
>> >> >> are contributed by no other than
>> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4, so this commit is the
>> >> >> peace-breaker which directly or indirectly causes the degradation.
>> >> >>
>> >> >> Does the map_writable flag passed to mmu_set_spte() function have
>> >> >> effect on PTE's PAT flag or increase the VMEXITs induced by that guest
>> >> >> tried to write read-only memory?
>> >> >>
>> >> >> Thanks,
>> >> >> Zhang Haoyu
>> >> >>
>> >> >
>> >> >There should be no read-only memory maps backing guest RAM.
>> >> >
>> >> >Can you confirm map_writable = false is being passed to __direct_map?
>> >> >(this should not happen, for guest RAM).
>> >> >And if it is false, please capture the associated GFN.
>> >> >
>> >> I added below check and printk at the start of __direct_map() at the fist
>> >> bad commit version,
>> >> --- kvm-612819c3c6e67bac8fceaa7cc402f13b1b63f7e4/arch/x86/kvm/mmu.c
>> >> 2013-07-26 18:44:05.0 +0800
>> >> +++ kvm-612819/arch/x86/kvm/mmu.c 2013-07-31 00:05:48.0
>> >> +0800
>> >> @@ -2223,6 +2223,9 @@ static int __direct_map(struct kvm_vcpu
>> >> int pt_write = 0;
>> >> gfn_t pseudo_gfn;
>> >>
>> >> +if (!map_writable)
>> >> +printk(KERN_ERR "%s: %s: gfn = %llu \n", __FILE__,
>> >> __func__, gfn);
>> >> +
>> >> for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
>> >> if (iterator.level == level) {
>> >> unsigned pte_access = ACC_ALL;
>> >>
>> >> I virsh-save the VM, and then virsh-restore it, so many GFNs were
>> >> printed, you can absolutely describe it as flooding.
>> >>
>> >The flooding you see happens during migrate to file stage because of dirty
>> >page tracking. If you clear dmesg after virsh-save you should not see any
>> >flooding after virsh-restore. I just checked with latest tree, I do not.
>>
>> I made a verification again.
>> I virsh-save the VM, during the saving stage, I run 'dmesg', no GFN printed,
>> maybe the switching from running stage to pause stage takes so short time,
>> no guest-write happens du
Re: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
On Mon, Aug 05, 2013 at 08:35:09AM +, Zhanghaoyu (A) wrote:
> >> >> >> hi all,
> >> >> >>
> >> >> >> I met similar problem to these, while performing live migration or
> >> >> >> save-restore test on the kvm platform (qemu:1.4.0, host:suse11sp2,
> >> >> >> guest:suse11sp2), running tele-communication software suite in
> >> >> >> guest,
> >> >> >> https://lists.gnu.org/archive/html/qemu-devel/2013-05/msg00098.html
> >> >> >> http://comments.gmane.org/gmane.comp.emulators.kvm.devel/102506
> >> >> >> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/100592
> >> >> >> https://bugzilla.kernel.org/show_bug.cgi?id=58771
> >> >> >>
> >> >> >> After live migration or virsh restore [savefile], one process's CPU
> >> >> >> utilization went up by about 30%, resulted in throughput
> >> >> >> degradation of this process.
> >> >> >>
> >> >> >> If EPT disabled, this problem gone.
> >> >> >>
> >> >> >> I suspect that kvm hypervisor has business with this problem.
> >> >> >> Based on above suspect, I want to find the two adjacent versions of
> >> >> >> kvm-kmod which triggers this problem or not (e.g. 2.6.39, 3.0-rc1),
> >> >> >> and analyze the differences between this two versions, or apply the
> >> >> >> patches between this two versions by bisection method, finally find
> >> >> >> the key patches.
> >> >> >>
> >> >> >> Any better ideas?
> >> >> >>
> >> >> >> Thanks,
> >> >> >> Zhang Haoyu
> >> >> >
> >> >> >I've attempted to duplicate this on a number of machines that are as
> >> >> >similar to yours as I am able to get my hands on, and so far have not
> >> >> >been able to see any performance degradation. And from what I've read
> >> >> >in the above links, huge pages do not seem to be part of the problem.
> >> >> >
> >> >> >So, if you are in a position to bisect the kernel changes, that would
> >> >> >probably be the best avenue to pursue in my opinion.
> >> >> >
> >> >> >Bruce
> >> >>
> >> >> I found the first bad
> >> >> commit([612819c3c6e67bac8fceaa7cc402f13b1b63f7e4] KVM: propagate fault
> >> >> r/w information to gup(), allow read-only memory) which triggers this
> >> >> problem by git bisecting the kvm kernel (download from
> >> >> https://git.kernel.org/pub/scm/virt/kvm/kvm.git) changes.
> >> >>
> >> >> And,
> >> >> git log 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4 -n 1 -p >
> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.log
> >> >> git diff
> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4~1..612819c3c6e67bac8fceaa7cc4
> >> >> 02f13b1b63f7e4 > 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.diff
> >> >>
> >> >> Then, I diffed 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.log and
> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.diff,
> >> >> came to a conclusion that all of the differences between
> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4~1 and
> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4
> >> >> are contributed by no other than
> >> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4, so this commit is the
> >> >> peace-breaker which directly or indirectly causes the degradation.
> >> >>
> >> >> Does the map_writable flag passed to mmu_set_spte() function have
> >> >> effect on PTE's PAT flag or increase the VMEXITs induced by that guest
> >> >> tried to write read-only memory?
> >> >>
> >> >> Thanks,
> >> >> Zhang Haoyu
> >> >>
> >> >
> >> >There should be no read-only memory maps backing guest RAM.
> >> >
> >> >Can you confirm map_writable = false is being passed to __direct_map?
> >> >(this should not happen, for guest RAM).
> >> >And if it is false, please capture the associated GFN.
> >> >
> >> I added below check and printk at the start of __direct_map() at the fist
> >> bad commit version,
> >> --- kvm-612819c3c6e67bac8fceaa7cc402f13b1b63f7e4/arch/x86/kvm/mmu.c
> >> 2013-07-26 18:44:05.0 +0800
> >> +++ kvm-612819/arch/x86/kvm/mmu.c 2013-07-31 00:05:48.0 +0800
> >> @@ -2223,6 +2223,9 @@ static int __direct_map(struct kvm_vcpu
> >> int pt_write = 0;
> >> gfn_t pseudo_gfn;
> >>
> >> +if (!map_writable)
> >> +printk(KERN_ERR "%s: %s: gfn = %llu \n", __FILE__,
> >> __func__, gfn);
> >> +
> >> for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
> >> if (iterator.level == level) {
> >> unsigned pte_access = ACC_ALL;
> >>
> >> I virsh-save the VM, and then virsh-restore it, so many GFNs were printed,
> >> you can absolutely describe it as flooding.
> >>
> >The flooding you see happens during migrate to file stage because of dirty
> >page tracking. If you clear dmesg after virsh-save you should not see any
> >flooding after virsh-restore. I just checked with latest tree, I do not.
>
> I made a verification again.
> I virsh-save the VM, during the saving stage, I run 'dmesg', no GFN printed,
> maybe the switching from running stage to pause stage takes so short time,
> no guest-write happens during this switching period.
> After the comple
RE: [Qemu-devel] vm performance degradation after kvm live migration or save-restore with EPT enabled
>> >> >> hi all,
>> >> >>
>> >> >> I met similar problem to these, while performing live migration or
>> >> >> save-restore test on the kvm platform (qemu:1.4.0, host:suse11sp2,
>> >> >> guest:suse11sp2), running tele-communication software suite in
>> >> >> guest,
>> >> >> https://lists.gnu.org/archive/html/qemu-devel/2013-05/msg00098.html
>> >> >> http://comments.gmane.org/gmane.comp.emulators.kvm.devel/102506
>> >> >> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/100592
>> >> >> https://bugzilla.kernel.org/show_bug.cgi?id=58771
>> >> >>
>> >> >> After live migration or virsh restore [savefile], one process's CPU
>> >> >> utilization went up by about 30%, resulted in throughput
>> >> >> degradation of this process.
>> >> >>
>> >> >> If EPT disabled, this problem gone.
>> >> >>
>> >> >> I suspect that kvm hypervisor has business with this problem.
>> >> >> Based on above suspect, I want to find the two adjacent versions of
>> >> >> kvm-kmod which triggers this problem or not (e.g. 2.6.39, 3.0-rc1),
>> >> >> and analyze the differences between this two versions, or apply the
>> >> >> patches between this two versions by bisection method, finally find
>> >> >> the key patches.
>> >> >>
>> >> >> Any better ideas?
>> >> >>
>> >> >> Thanks,
>> >> >> Zhang Haoyu
>> >> >
>> >> >I've attempted to duplicate this on a number of machines that are as
>> >> >similar to yours as I am able to get my hands on, and so far have not
>> >> >been able to see any performance degradation. And from what I've read in
>> >> >the above links, huge pages do not seem to be part of the problem.
>> >> >
>> >> >So, if you are in a position to bisect the kernel changes, that would
>> >> >probably be the best avenue to pursue in my opinion.
>> >> >
>> >> >Bruce
>> >>
>> >> I found the first bad
>> >> commit([612819c3c6e67bac8fceaa7cc402f13b1b63f7e4] KVM: propagate fault
>> >> r/w information to gup(), allow read-only memory) which triggers this
>> >> problem by git bisecting the kvm kernel (download from
>> >> https://git.kernel.org/pub/scm/virt/kvm/kvm.git) changes.
>> >>
>> >> And,
>> >> git log 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4 -n 1 -p >
>> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.log
>> >> git diff
>> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4~1..612819c3c6e67bac8fceaa7cc4
>> >> 02f13b1b63f7e4 > 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.diff
>> >>
>> >> Then, I diffed 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.log and
>> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4.diff,
>> >> came to a conclusion that all of the differences between
>> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4~1 and
>> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4
>> >> are contributed by no other than
>> >> 612819c3c6e67bac8fceaa7cc402f13b1b63f7e4, so this commit is the
>> >> peace-breaker which directly or indirectly causes the degradation.
>> >>
>> >> Does the map_writable flag passed to mmu_set_spte() function have effect
>> >> on PTE's PAT flag or increase the VMEXITs induced by that guest tried to
>> >> write read-only memory?
>> >>
>> >> Thanks,
>> >> Zhang Haoyu
>> >>
>> >
>> >There should be no read-only memory maps backing guest RAM.
>> >
>> >Can you confirm map_writable = false is being passed to __direct_map? (this
>> >should not happen, for guest RAM).
>> >And if it is false, please capture the associated GFN.
>> >
>> I added below check and printk at the start of __direct_map() at the fist
>> bad commit version,
>> --- kvm-612819c3c6e67bac8fceaa7cc402f13b1b63f7e4/arch/x86/kvm/mmu.c
>> 2013-07-26 18:44:05.0 +0800
>> +++ kvm-612819/arch/x86/kvm/mmu.c 2013-07-31 00:05:48.0 +0800
>> @@ -2223,6 +2223,9 @@ static int __direct_map(struct kvm_vcpu
>> int pt_write = 0;
>> gfn_t pseudo_gfn;
>>
>> +if (!map_writable)
>> +printk(KERN_ERR "%s: %s: gfn = %llu \n", __FILE__,
>> __func__, gfn);
>> +
>> for_each_shadow_entry(vcpu, (u64)gfn << PAGE_SHIFT, iterator) {
>> if (iterator.level == level) {
>> unsigned pte_access = ACC_ALL;
>>
>> I virsh-save the VM, and then virsh-restore it, so many GFNs were printed,
>> you can absolutely describe it as flooding.
>>
>The flooding you see happens during migrate to file stage because of dirty
>page tracking. If you clear dmesg after virsh-save you should not see any
>flooding after virsh-restore. I just checked with latest tree, I do not.
I made a verification again.
I virsh-save the VM, during the saving stage, I run 'dmesg', no GFN printed,
maybe the switching from running stage to pause stage takes so short time,
no guest-write happens during this switching period.
After the completion of saving operation, I run 'demsg -c' to clear the buffer
all the same, then I virsh-restore the VM, so many GFNs are printed by running
'dmesg',
and I also run 'tail -f /var/log/messages' during the restoring stage, so many
GFNs are flooded dynamically too.
I'm s
