From 3910197f4103e48197dbe05634a4e2e388dc105b Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Fri, 21 Jun 2013 06:20:02 +0200 Subject: [PATCH 06/21] block: add the support to drain throttled requests RH-Author: Fam Zheng Message-id: <1371795611-7208-7-git-send-email-famz@redhat.com> Patchwork-id: 52080 O-Subject: [PATCH RHEL-6.5 qemu-kvm v3 06/15] block: add the support to drain throttled requests Bugzilla: 956825 RH-Acked-by: Paolo Bonzini RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Laszlo Ersek From: Zhi Yong Wu Signed-off-by: Zhi Yong Wu [ Iterate until all block devices have processed all requests, add comments. - Paolo ] Signed-off-by: Paolo Bonzini Signed-off-by: Kevin Wolf (cherry picked from commit 4c355d53c6a5444b78b695f8bf106f1ffcba45e1) qemu_aio_wait is void type, can't used to set busy flag. Calling flush in the loop to avoid missing throttled reqs. Signed-off-by: Fam Zheng --- block.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) Signed-off-by: Miroslav Rezanina --- block.c | 22 +++++++++++++++++++++- 1 files changed, 21 insertions(+), 1 deletions(-) diff --git a/block.c b/block.c index 4604aba..800896f 100644 --- a/block.c +++ b/block.c @@ -1088,12 +1088,32 @@ void bdrv_close_all(void) * * This function does not flush data to disk, use bdrv_flush_all() for that * after calling this function. + * + * Note that completion of an asynchronous I/O operation can trigger any + * number of other I/O operations on other devices---for example a coroutine + * can be arbitrarily complex and a constant flow of I/O can come until the + * coroutine is complete. Because of this, it is not possible to have a + * function to drain a single device's I/O queue. */ void bdrv_drain_all(void) { BlockDriverState *bs; + bool busy; - qemu_aio_flush(); + do { + busy = false; + qemu_aio_flush(); + + /* FIXME: We do not have timer support here, so this is effectively + * a busy wait. + */ + QTAILQ_FOREACH(bs, &bdrv_states, list) { + if (!qemu_co_queue_empty(&bs->throttled_reqs)) { + qemu_co_queue_restart_all(&bs->throttled_reqs); + busy = true; + } + } + } while (busy); /* If requests are still pending there is a bug somewhere */ QTAILQ_FOREACH(bs, &bdrv_states, list) { -- 1.7.1