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authorStefan Hajnoczi <stefanha@redhat.com>2013-04-05 11:32:19 +0200
committerKevin Wolf <kwolf@redhat.com>2013-04-05 18:58:05 +0200
commit5905fbc9c94ccd744c1b249472eafcc2d827548a (patch)
tree71685e79fabea4499032719f71671420dec26a6b /include
parent76534da749ceb3b4c13ec09b173bcf6d6c2e36d4 (diff)
block: fix I/O throttling accounting blind spot
I/O throttling relies on bdrv_acct_done() which is called when a request completes. This leaves a blind spot since we only charge for completed requests, not submitted requests. For example, if there is 1 operation remaining in this time slice the guest could submit 3 operations and they will all be submitted successfully since they don't actually get accounted for until they complete. Originally we probably thought this is okay since the requests will be accounted when the time slice is extended. In practice it causes fluctuations since the guest can exceed its I/O limit and it will be punished for this later on. Account for I/O upon submission so that I/O limits are enforced properly. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Tested-By: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'include')
-rw-r--r--include/block/block_int.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 0986a2d6ac..83941d8672 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -256,7 +256,7 @@ struct BlockDriverState {
int64_t slice_start;
int64_t slice_end;
BlockIOLimit io_limits;
- BlockIOBaseValue io_base;
+ BlockIOBaseValue slice_submitted;
CoQueue throttled_reqs;
QEMUTimer *block_timer;
bool io_limits_enabled;