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Re: [Qemu-devel] [PATCH v3 02/29] block: Inherit opt_transfer_length
From: |
Benoît Canet |
Subject: |
Re: [Qemu-devel] [PATCH v3 02/29] block: Inherit opt_transfer_length |
Date: |
Fri, 17 Jan 2014 23:42:58 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Le Friday 17 Jan 2014 à 15:14:52 (+0100), Kevin Wolf a écrit :
> When there is a format driver between the backend, it's not guaranteed
> that exposing the opt_transfer_length for the format driver results in
> the optimal requests (because of fragmentation etc.), but it can't make
> things worse, so let's just do it.
>
> Signed-off-by: Kevin Wolf <address@hidden>
> Reviewed-by: Wenchao Xia <address@hidden>
> Reviewed-by: Max Reitz <address@hidden>
> ---
> block.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/block.c b/block.c
> index 99e69da..20f85cb 100644
> --- a/block.c
> +++ b/block.c
> @@ -485,7 +485,25 @@ static int bdrv_refresh_limits(BlockDriverState *bs)
>
> memset(&bs->bl, 0, sizeof(bs->bl));
>
> - if (drv && drv->bdrv_refresh_limits) {
> + if (!drv) {
> + return 0;
> + }
> +
> + /* Take some limits from the children as a default */
> + if (bs->file) {
> + bdrv_refresh_limits(bs->file);
> + bs->bl.opt_transfer_length = bs->file->bl.opt_transfer_length;
> + }
> +
> + if (bs->backing_hd) {
> + bdrv_refresh_limits(bs->backing_hd);
> + bs->bl.opt_transfer_length =
> + MAX(bs->bl.opt_transfer_length,
> + bs->backing_hd->bl.opt_transfer_length);
> + }
> +
> + /* Then let the driver override it */
> + if (drv->bdrv_refresh_limits) {
> return drv->bdrv_refresh_limits(bs);
> }
Reviewed-by: Benoît Canet <address@hidden>
>
> --
> 1.8.1.4
>
>
- [Qemu-devel] [PATCH v3 00/29] block: Support for 512b-on-4k emulation, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 02/29] block: Inherit opt_transfer_length, Kevin Wolf, 2014/01/17
- Re: [Qemu-devel] [PATCH v3 02/29] block: Inherit opt_transfer_length,
Benoît Canet <=
- [Qemu-devel] [PATCH v3 03/29] block: Update BlockLimits when they might have changed, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 04/29] qemu_memalign: Allow small alignments, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 05/29] block: Detect unaligned length in bdrv_qiov_is_aligned(), Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 06/29] block: Don't use guest sector size for qemu_blockalign(), Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 08/29] raw: Probe required direct I/O alignment, Kevin Wolf, 2014/01/17
- [Qemu-devel] [PATCH v3 09/29] block: Introduce bdrv_aligned_preadv(), Kevin Wolf, 2014/01/17