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Re: [PATCH v3] virtio: increase virtqueue size for virtio-scsi and virti
From: |
Stefan Hajnoczi |
Subject: |
Re: [PATCH v3] virtio: increase virtqueue size for virtio-scsi and virtio-blk |
Date: |
Wed, 19 Feb 2020 15:14:16 +0000 |
On Fri, Feb 14, 2020 at 10:46:48AM +0300, Denis Plotnikov wrote:
> The goal is to reduce the amount of requests issued by a guest on
> 1M reads/writes. This rises the performance up to 4% on that kind of
> disk access pattern.
>
> The maximum chunk size to be used for the guest disk accessing is
> limited with seg_max parameter, which represents the max amount of
> pices in the scatter-geather list in one guest disk request.
>
> Since seg_max is virqueue_size dependent, increasing the virtqueue
> size increases seg_max, which, in turn, increases the maximum size
> of data to be read/write from a guest disk.
>
> More details in the original problem statment:
> https://lists.gnu.org/archive/html/qemu-devel/2017-12/msg03721.html
>
> Suggested-by: Denis V. Lunev <address@hidden>
> Signed-off-by: Denis Plotnikov <address@hidden>
>
> ---
>
> v3:
> * typos fixed
>
> v2:
> * seg_max default value changing removed
> ---
> hw/block/virtio-blk.c | 2 +-
> hw/core/machine.c | 2 ++
> hw/scsi/virtio-scsi.c | 2 +-
> 3 files changed, 4 insertions(+), 2 deletions(-)
Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block
Stefan
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