On 31/08/17 03:20, Stefan Hajnoczi wrote: > On Tue, Aug 22, 2017 at 02:56:00PM +1000, Alexey Kardashevskiy wrote: >> On 19/08/17 12:46, Alexey Kardashevskiy wrote: >>> On 19/08/17 01:18, Eric Blake wrote: >>>> On 08/18/2017 08:31 AM, Stefan Hajnoczi wrote: >>>>> Most qcow2 files are uncompressed so it is wasteful to allocate (32 + 1) >>>>> * cluster_size + 512 bytes upfront. Allocate s->cluster_cache and >>>>> s->cluster_data when the first read operation is performance on a >>>>> compressed cluster. >>>>> >>>>> The buffers are freed in .bdrv_close(). .bdrv_open() no longer has any >>>>> code paths that can allocate these buffers, so remove the free functions >>>>> in the error code path. >>>>> >>>>> Reported-by: Alexey Kardashevskiy <a...@ozlabs.ru> >>>>> Cc: Kevin Wolf <kw...@redhat.com> >>>>> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> >>>>> --- >>>>> Alexey: Does this improve your memory profiling results? >>>> >>>> Is this a regression from earlier versions? >>> >>> Hm, I have not thought about this. >>> >>> So. I did bisect and this started happening from >>> 9a4c0e220d8a4f82b5665d0ee95ef94d8e1509d5 >>> "hw/virtio-pci: fix virtio behaviour" >>> >>> Before that, the very same command line would take less than 1GB of >>> resident memory. That thing basically enforces virtio-1.0 for QEMU <=2.6 >>> which means that upstream with "-machine pseries-2.6" works fine (less than >>> 1GB), "-machine pseries-2.7" does not (close to 7GB, sometime even 9GB). >>> >>> Then I tried bisecting again, with >>> "scsi=off,disable-modern=off,disable-legacy=on" on my 150 virtio-block >>> devices, started from >>> e266d421490e0 "virtio-pci: add flags to enable/disable legacy/modern" (it >>> added the disable-modern switch) which uses 2GB of memory. >>> >>> I ended up with ada434cd0b44 "virtio-pci: implement cfg capability". >>> >>> Then I removed proxy->modern_as on v2.10.0-rc3 (see below) and got 1.5GB of >>> used memory (yay!) >>> >>> I do not really know how to reinterpret all of this, do you? >> >> >> Anyone, ping? Should I move the conversation to the original thread? Any >> hacks to try with libc? > > I suggest a new top-level thread with Michael Tsirkin CCed.
I am continuing in the original "Memory use with >100 virtio devices" thread and the problem is more generic than virtio, it is just easier to reproduce it with virtio, that's all. -- Alexey
