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authorAlexander Yarygin <yarygin@linux.vnet.ibm.com>2015-06-10 14:38:17 +0300
committerStefan Hajnoczi <stefanha@redhat.com>2015-06-23 15:06:16 +0100
commitf406c03c093f1451ac0ba7fde31eeb78e5e5e417 (patch)
tree52b1a39551c0db3c413c42e49ec3e9f01f800dc6
parenta3206972a9eab65ec8e8f9ae320ad628ba4b58f1 (diff)
block: Let bdrv_drain_all() to call aio_poll() for each AioContext
After the commit 9b536adc ("block: acquire AioContext in bdrv_drain_all()") the aio_poll() function got called for every BlockDriverState, in assumption that every device may have its own AioContext. If we have thousands of disks attached, there are a lot of BlockDriverStates but only a few AioContexts, leading to tons of unnecessary aio_poll() calls. This patch changes the bdrv_drain_all() function allowing it find shared AioContexts and to call aio_poll() only for unique ones. Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Cornelia Huck <cornelia.huck@de.ibm.com> Cc: Kevin Wolf <kwolf@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> Message-id: 1433936297-7098-4-git-send-email-yarygin@linux.vnet.ibm.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r--block/io.c42
1 files changed, 26 insertions, 16 deletions
diff --git a/block/io.c b/block/io.c
index 9cc729be7e..43f85ab452 100644
--- a/block/io.c
+++ b/block/io.c
@@ -233,17 +233,6 @@ static bool bdrv_requests_pending(BlockDriverState *bs)
return false;
}
-static bool bdrv_drain_one(BlockDriverState *bs)
-{
- bool bs_busy;
-
- bdrv_flush_io_queue(bs);
- bdrv_start_throttled_reqs(bs);
- bs_busy = bdrv_requests_pending(bs);
- bs_busy |= aio_poll(bdrv_get_aio_context(bs), bs_busy);
- return bs_busy;
-}
-
/*
* Wait for pending requests to complete on a single BlockDriverState subtree
*
@@ -256,8 +245,13 @@ static bool bdrv_drain_one(BlockDriverState *bs)
*/
void bdrv_drain(BlockDriverState *bs)
{
- while (bdrv_drain_one(bs)) {
+ bool busy = true;
+
+ while (busy) {
/* Keep iterating */
+ bdrv_flush_io_queue(bs);
+ busy = bdrv_requests_pending(bs);
+ busy |= aio_poll(bdrv_get_aio_context(bs), busy);
}
}
@@ -278,6 +272,7 @@ void bdrv_drain_all(void)
/* Always run first iteration so any pending completion BHs run */
bool busy = true;
BlockDriverState *bs = NULL;
+ GSList *aio_ctxs = NULL, *ctx;
while ((bs = bdrv_next(bs))) {
AioContext *aio_context = bdrv_get_aio_context(bs);
@@ -287,17 +282,30 @@ void bdrv_drain_all(void)
block_job_pause(bs->job);
}
aio_context_release(aio_context);
+
+ if (!aio_ctxs || !g_slist_find(aio_ctxs, aio_context)) {
+ aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
+ }
}
while (busy) {
busy = false;
- bs = NULL;
- while ((bs = bdrv_next(bs))) {
- AioContext *aio_context = bdrv_get_aio_context(bs);
+ for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
+ AioContext *aio_context = ctx->data;
+ bs = NULL;
aio_context_acquire(aio_context);
- busy |= bdrv_drain_one(bs);
+ while ((bs = bdrv_next(bs))) {
+ if (aio_context == bdrv_get_aio_context(bs)) {
+ bdrv_flush_io_queue(bs);
+ if (bdrv_requests_pending(bs)) {
+ busy = true;
+ aio_poll(aio_context, busy);
+ }
+ }
+ }
+ busy |= aio_poll(aio_context, false);
aio_context_release(aio_context);
}
}
@@ -312,6 +320,7 @@ void bdrv_drain_all(void)
}
aio_context_release(aio_context);
}
+ g_slist_free(aio_ctxs);
}
/**
@@ -2562,4 +2571,5 @@ void bdrv_flush_io_queue(BlockDriverState *bs)
} else if (bs->file) {
bdrv_flush_io_queue(bs->file);
}
+ bdrv_start_throttled_reqs(bs);
}