On 08/21/2017 08:55 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. > > This patch can result in significant memory savings when many qcow2 > disks are attached or backing file chains are long: > > Before 12.81% (1,023,193,088B) > After 5.36% (393,893,888B) > > Reported-by: Alexey Kardashevskiy <a...@ozlabs.ru> > Tested-by: Alexey Kardashevskiy <a...@ozlabs.ru> > Cc: Kevin Wolf <kw...@redhat.com> > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > ---
Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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