Re: crash with CFS v4 and qemu/kvm (was: [patch] CFS scheduler, v4)
On Monday 23 April 2007, Ingo Molnar wrote: > * Christian Hesse <[EMAIL PROTECTED]> wrote: > > On Friday 20 April 2007, Ingo Molnar wrote: > > > i'm pleased to announce release -v4 of the CFS patchset. > > > > Hi Ingo, hi Avi, hi all, > > > > I'm trying to use kvm-20 with cfs v4 and get a crash: > > > > [EMAIL PROTECTED]:~$ /usr/local/kvm/bin/qemu -snapshot > > /mnt/data/virtual/qemu/winxp.img kvm_run: failed entry, reason 7 > > kvm_run returned -8 > > > > It works (though it is a bit slow) if I start qemu with strace, so for > > me it looks like a race condition? > > hm. Can you work it around with: > >echo 0 > /proc/sys/kernel/sched_granularity_ns > > ? > > If yes then this is a wakeup race: some piece of code relies on the > upstream scheduler preempting the waker task immediately in 99% of the > cases. > > and you might want to test -v5 too which i released earlier today. It > has no bugfix in this area though, so it will likely still trigger this > race - but it will also hopefully be even more pleasant to use than -v4 > ;-) Hi Ingo, This was kvm's fault. It works perfectly now without modifications to the scheduler. If anybody is interested in details please see the kvm mailing list archives. -- Regards, Chris signature.asc Description: This is a digitally signed message part.
Re: crash with CFS v4 and qemu/kvm (was: [patch] CFS scheduler, v4)
On Monday 23 April 2007, Ingo Molnar wrote: * Christian Hesse [EMAIL PROTECTED] wrote: On Friday 20 April 2007, Ingo Molnar wrote: i'm pleased to announce release -v4 of the CFS patchset. Hi Ingo, hi Avi, hi all, I'm trying to use kvm-20 with cfs v4 and get a crash: [EMAIL PROTECTED]:~$ /usr/local/kvm/bin/qemu -snapshot /mnt/data/virtual/qemu/winxp.img kvm_run: failed entry, reason 7 kvm_run returned -8 It works (though it is a bit slow) if I start qemu with strace, so for me it looks like a race condition? hm. Can you work it around with: echo 0 /proc/sys/kernel/sched_granularity_ns ? If yes then this is a wakeup race: some piece of code relies on the upstream scheduler preempting the waker task immediately in 99% of the cases. and you might want to test -v5 too which i released earlier today. It has no bugfix in this area though, so it will likely still trigger this race - but it will also hopefully be even more pleasant to use than -v4 ;-) Hi Ingo, This was kvm's fault. It works perfectly now without modifications to the scheduler. If anybody is interested in details please see the kvm mailing list archives. -- Regards, Chris signature.asc Description: This is a digitally signed message part.
Re: crash with CFS v4 and qemu/kvm (was: [patch] CFS scheduler, v4)
* Christian Hesse <[EMAIL PROTECTED]> wrote: > On Friday 20 April 2007, Ingo Molnar wrote: > > i'm pleased to announce release -v4 of the CFS patchset. > > Hi Ingo, hi Avi, hi all, > > I'm trying to use kvm-20 with cfs v4 and get a crash: > > [EMAIL PROTECTED]:~$ /usr/local/kvm/bin/qemu -snapshot > /mnt/data/virtual/qemu/winxp.img > kvm_run: failed entry, reason 7 > kvm_run returned -8 > > It works (though it is a bit slow) if I start qemu with strace, so for > me it looks like a race condition? hm. Can you work it around with: echo 0 > /proc/sys/kernel/sched_granularity_ns ? If yes then this is a wakeup race: some piece of code relies on the upstream scheduler preempting the waker task immediately in 99% of the cases. and you might want to test -v5 too which i released earlier today. It has no bugfix in this area though, so it will likely still trigger this race - but it will also hopefully be even more pleasant to use than -v4 ;-) Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
crash with CFS v4 and qemu/kvm (was: [patch] CFS scheduler, v4)
On Friday 20 April 2007, Ingo Molnar wrote: > i'm pleased to announce release -v4 of the CFS patchset. Hi Ingo, hi Avi, hi all, I'm trying to use kvm-20 with cfs v4 and get a crash: [EMAIL PROTECTED]:~$ /usr/local/kvm/bin/qemu -snapshot /mnt/data/virtual/qemu/winxp.img kvm_run: failed entry, reason 7 kvm_run returned -8 It works (though it is a bit slow) if I start qemu with strace, so for me it looks like a race condition? I did not test any earlier versions of cfs and kvm in combination - I can't say if it happens there as well. -- Regards, Chris signature.asc Description: This is a digitally signed message part.
crash with CFS v4 and qemu/kvm (was: [patch] CFS scheduler, v4)
On Friday 20 April 2007, Ingo Molnar wrote: i'm pleased to announce release -v4 of the CFS patchset. Hi Ingo, hi Avi, hi all, I'm trying to use kvm-20 with cfs v4 and get a crash: [EMAIL PROTECTED]:~$ /usr/local/kvm/bin/qemu -snapshot /mnt/data/virtual/qemu/winxp.img kvm_run: failed entry, reason 7 kvm_run returned -8 It works (though it is a bit slow) if I start qemu with strace, so for me it looks like a race condition? I did not test any earlier versions of cfs and kvm in combination - I can't say if it happens there as well. -- Regards, Chris signature.asc Description: This is a digitally signed message part.
Re: crash with CFS v4 and qemu/kvm (was: [patch] CFS scheduler, v4)
* Christian Hesse [EMAIL PROTECTED] wrote: On Friday 20 April 2007, Ingo Molnar wrote: i'm pleased to announce release -v4 of the CFS patchset. Hi Ingo, hi Avi, hi all, I'm trying to use kvm-20 with cfs v4 and get a crash: [EMAIL PROTECTED]:~$ /usr/local/kvm/bin/qemu -snapshot /mnt/data/virtual/qemu/winxp.img kvm_run: failed entry, reason 7 kvm_run returned -8 It works (though it is a bit slow) if I start qemu with strace, so for me it looks like a race condition? hm. Can you work it around with: echo 0 /proc/sys/kernel/sched_granularity_ns ? If yes then this is a wakeup race: some piece of code relies on the upstream scheduler preempting the waker task immediately in 99% of the cases. and you might want to test -v5 too which i released earlier today. It has no bugfix in this area though, so it will likely still trigger this race - but it will also hopefully be even more pleasant to use than -v4 ;-) Ingo - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
