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? > > > Note: 1GB..9GB numbers from below are the peak values from valgrind's
s/from below/from above/ , sorry, bad cut-n-paste :) -- Alexey
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