Re: [Qemu-devel] [PULL 06/49] virtio: move allocation to virtqueue_pop/vring_pop

[Michael S. Tsirkin]

On Fri, Feb 05, 2016 at 12:52:55PM +0000, Peter Maydell wrote:
> On 4 February 2016 at 21:51, Michael S. Tsirkin <address@hidden> wrote:
> > From: Paolo Bonzini <address@hidden>
> >
> > The return code of virtqueue_pop/vring_pop is unused except to check for
> > errors or 0.  We can thus easily move allocation inside the functions
> > and just return a pointer to the VirtQueueElement.
> >
> > The advantage is that we will be able to allocate only the space that
> > is needed for the actual size of the s/g list instead of the full
> > VIRTQUEUE_MAX_SIZE items.  Currently VirtQueueElement takes about 48K
> > of memory, and this kind of allocation puts a lot of stress on malloc.
> > By cutting the size by two or three orders of magnitude, malloc can
> > use much more efficient algorithms.
> >
> > The patch is pretty large, but changes to each device are testable
> > more or less independently.  Splitting it would mostly add churn.
> >
> > Signed-off-by: Paolo Bonzini <address@hidden>
> > Reviewed-by: Michael S. Tsirkin <address@hidden>
> > Signed-off-by: Michael S. Tsirkin <address@hidden>
> > Reviewed-by: Cornelia Huck <address@hidden>
> > ---
> >  hw/9pfs/virtio-9p.h                 |  2 +-
> >  include/hw/virtio/dataplane/vring.h |  2 +-
> >  include/hw/virtio/virtio-balloon.h  |  2 +-
> >  include/hw/virtio/virtio-blk.h      |  3 +-
> >  include/hw/virtio/virtio-net.h      |  2 +-
> >  include/hw/virtio/virtio-scsi.h     |  2 +-
> >  include/hw/virtio/virtio-serial.h   |  2 +-
> >  include/hw/virtio/virtio.h          |  2 +-
> >  hw/9pfs/9p.c                        |  2 +-
> >  hw/9pfs/virtio-9p-device.c          | 17 ++++----
> >  hw/block/dataplane/virtio-blk.c     | 11 +++--
> >  hw/block/virtio-blk.c               | 15 +++----
> >  hw/char/virtio-serial-bus.c         | 80 
> > +++++++++++++++++++++++--------------
> >  hw/display/virtio-gpu.c             | 21 ++++++----
> >  hw/input/virtio-input.c             | 24 +++++++----
> >  hw/net/virtio-net.c                 | 69 ++++++++++++++++++++------------
> >  hw/scsi/virtio-scsi-dataplane.c     | 15 +++----
> >  hw/scsi/virtio-scsi.c               | 18 ++++-----
> >  hw/virtio/dataplane/vring.c         | 18 +++++----
> >  hw/virtio/virtio-balloon.c          | 22 ++++++----
> >  hw/virtio/virtio-rng.c              | 10 +++--
> >  hw/virtio/virtio.c                  | 12 ++++--
> >  roms/seabios                        |  2 +-
> >  23 files changed, 210 insertions(+), 143 deletions(-)
> 
> > --- a/roms/seabios
> > +++ b/roms/seabios
> > @@ -1 +1 @@
> > -Subproject commit 01a84bea2d28a19d2405c1ecac4bdef17683cc0c
> > +Subproject commit 33fbe13a3e2a01e0ba1087a8feed801a0451db21
> > --
> > MST
> 
> Hi. This commit in this pull request includes a seabios submodule
> update, but the commit message says nothing about it. Is it
> really supposed to be here?
> 
> thanks
> -- PMM

Not sure how it got here - I didn't notice.
I'll redo the pull request.

-- 
MST