diff mbox

[01/12] block: Don't disable I/O throttling on sync requests

Message ID 1458660792-3035-2-git-send-email-kwolf@redhat.com
State New, archived
Headers show

Commit Message

Kevin Wolf March 22, 2016, 3:33 p.m. UTC
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 <kwolf@redhat.com>
---
 block/io.c | 11 -----------
 1 file changed, 11 deletions(-)

Comments

Eric Blake March 22, 2016, 9:40 p.m. UTC | #1
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 <kwolf@redhat.com>
> ---
>  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 <eblake@redhat.com>
diff mbox

Patch

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));
-        bdrv_io_limits_disable(bs);
-    }
-
     if (qemu_in_coroutine()) {
         /* Fast-path if already in coroutine context */
         bdrv_rw_co_entry(&rwco);