From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40147) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bw3kc-0004GD-Fs for qemu-devel@nongnu.org; Mon, 17 Oct 2016 04:58:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bw3kY-00069a-Fi for qemu-devel@nongnu.org; Mon, 17 Oct 2016 04:58:30 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:56931) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1bw3kY-000694-60 for qemu-devel@nongnu.org; Mon, 17 Oct 2016 04:58:26 -0400 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u9H8sBCR107993 for ; Mon, 17 Oct 2016 04:58:24 -0400 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0a-001b2d01.pphosted.com with ESMTP id 264u0r9hj0-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 17 Oct 2016 04:58:24 -0400 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 17 Oct 2016 09:58:22 +0100 References: <1476380062-18001-1-git-send-email-pbonzini@redhat.com> From: Christian Borntraeger Date: Mon, 17 Oct 2016 10:58:19 +0200 MIME-Version: 1.0 In-Reply-To: <1476380062-18001-1-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Message-Id: <008ad711-fa2a-32d5-832e-e93508a06807@de.ibm.com> Subject: Re: [Qemu-devel] [PATCH 00/18] dataplane: remove RFifoLock (including almost all previously sent patches) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, stefanha@redhat.com, qemu-block@nongnu.org On 10/13/2016 07:34 PM, Paolo Bonzini wrote: > This patch reorganizes aio_poll callers to establish new rules for > dataplane locking. The idea is that I/O operations on a dataplane > BDS (i.e. one where the AioContext is not the main one) do not call > aio_poll anymore. Instead, they wait for the operation to end in the > other I/O thread, at which point the other I/O thread calls bdrv_wakeup > to wake up the main thread. > > With this change, only one thread runs aio_poll for an AioContext. > While aio_context_acquire/release is still needed to protect the BDSes, > it need not interrupt the other thread's event loop anymore, and therefore > it does not need contention callbacks anymore. Thus the patch can remove > RFifoLock. This fixes possible hangs in bdrv_drain_all, reproducible (for > example) by unplugging a virtio-scsi-dataplane device while there is I/O > going on for a virtio-blk-dataplane on the same I/O thread. Have you seen improvements or deteriorations in performance with single disks or multiple disks? Is there a branch?