[Qemu-devel] Re: [PATCH] qemu-kvm: clear only essential parts of VirtIOBlockReq on object allocation - RESUBMIT

[Anthony Liguori]

Saul Tamari wrote:
> This patch reduces the size of memory being cleared on every virtio-blk IO.
>
> Improve number of IOPS when using avirtio-blk device.
>
> On every virtio-blk IO command passed to QEMU, virtio_blk_alloc_request()
> allocates and clears (with qemu_mallocz()) a VirtIOBlockReq object.
> The sizeof(VirtIOBlockReq) equals 41040 bytes on my x86-64 machine.
> By moving the 'elem' variable to the end of VirtIOBlockReq and
> clearing only upto the address of the 'elem.in_addr' field, the
> memset() call now clears only 80 bytes.
>
>
> Signed-off-by: Saul Tamari <address@hidden>
> ---
>
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index 2630b99..de74b00 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -79,12 +79,13 @@ static inline void virtio_identify_template(struct
> virtio_blk_config *bc)
>   

This patch is whitespace damaged by your mailer.

Regards,

Anthony Liguori