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Re: [Qemu-devel] [PATCH 01/12] block: Don't disable I/O throttling on sy
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 01/12] block: Don't disable I/O throttling on sync requests |
Date: |
Tue, 22 Mar 2016 15:40:09 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 03/22/2016 09:33 AM, Kevin Wolf wrote:
> We had to disable I/O throttling with synchronous requests because we
> didn't use to run timers in nested event loops when the code was
> introduced. This isn't true any more, and throttling works just fine
> even when using the synchronous API.
>
> The removed code is in fact dead code since commit a8823a3b ('block: Use
> blk_co_pwritev() for blk_write()') because I/O throttling can only be
> set on the top layer, but BlockBackend always uses the coroutine
> interface now instead of using the sync API emulation in block.c.
>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> block/io.c | 11 -----------
> 1 file changed, 11 deletions(-)
>
> diff --git a/block/io.c b/block/io.c
> index cce508a..e4438da 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -561,17 +561,6 @@ static int bdrv_prwv_co(BlockDriverState *bs, int64_t
> offset,
> .flags = flags,
> };
>
> - /**
> - * In sync call context, when the vcpu is blocked, this throttling timer
> - * will not fire; so the I/O throttling function has to be disabled here
> - * if it has been enabled.
> - */
> - if (bs->io_limits_enabled) {
> - fprintf(stderr, "Disabling I/O throttling on '%s' due "
> - "to synchronous I/O.\n", bdrv_get_device_name(bs));
And we get rid of an fprintf(). Nice bonus.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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[Qemu-devel] [PATCH 04/12] block: throttle-groups: Use BlockBackend pointers internally, Kevin Wolf, 2016/03/22
[Qemu-devel] [PATCH 08/12] block: Move I/O throttling configuration functions to BlockBackend, Kevin Wolf, 2016/03/22
[Qemu-devel] [PATCH 11/12] block: Decouple throttling from BlockDriverState, Kevin Wolf, 2016/03/22
[Qemu-devel] [PATCH 05/12] block: Convert throttle_group_get_name() to BlockBackend, Kevin Wolf, 2016/03/22