From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45411) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z091y-0000Fc-Sd for qemu-devel@nongnu.org; Wed, 03 Jun 2015 09:48:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z091v-0001i8-IV for qemu-devel@nongnu.org; Wed, 03 Jun 2015 09:48:30 -0400 Received: from e06smtp14.uk.ibm.com ([195.75.94.110]:57613) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z091v-0001hK-97 for qemu-devel@nongnu.org; Wed, 03 Jun 2015 09:48:27 -0400 Received: from /spool/local by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 3 Jun 2015 14:48:24 +0100 From: Alexander Yarygin Date: Wed, 3 Jun 2015 16:46:13 +0300 Message-Id: <1433339175-12300-1-git-send-email-yarygin@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH RFC 0/2] Fix slow startup with many disks List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Alexander Yarygin , Ekaterina Tumanova , Christian Borntraeger , Stefan Hajnoczi , Cornelia Huck , Paolo Bonzini During reset the aio_poll() function is called at least amount_of_disks^2 times: for_each disk virtio_blk_reset() bdrv_drain_all() for_each disk aio_poll() For example, startup with 1000 disks takes over 13 minutes. Patch 1/2 removes inner loop by using bdrv_drain() instead of bdrv_drain_all(). bdrv_drain() works on one disk at time. Since bdrv_drain_all() is still called in other places, patch 2/2 optimizes it for cases, where there are more disks than iothreads. Thanks. Alexander Yarygin (2): block-backend: Introduce blk_drain() and replace blk_drain_all() block: Let bdrv_drain_all() to call aio_poll() for each AioContext block/block-backend.c | 5 +++++ block/io.c | 42 ++++++++++++++++++++++++++---------------- hw/block/virtio-blk.c | 2 +- include/sysemu/block-backend.h | 1 + 4 files changed, 33 insertions(+), 17 deletions(-) -- 1.9.1