From patchwork Wed May 17 22:10:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13245782 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9CD31C7EE2C for ; Wed, 17 May 2023 22:10:58 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.536079.834190 (Exim 4.92) (envelope-from ) id 1pzPLx-0004sd-0T; Wed, 17 May 2023 22:10:37 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 536079.834190; Wed, 17 May 2023 22:10:36 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pzPLw-0004sW-Tw; Wed, 17 May 2023 22:10:36 +0000 Received: by outflank-mailman (input) for mailman id 536079; Wed, 17 May 2023 22:10:36 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pzPLw-0004sP-4b for xen-devel@lists.xenproject.org; Wed, 17 May 2023 22:10:36 +0000 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id a3f51616-f4ff-11ed-b22a-6b7b168915f2; Thu, 18 May 2023 00:10:33 +0200 (CEST) Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-59-lSLG9I1HP4uawS9h9gPBxQ-1; Wed, 17 May 2023 18:10:26 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EB521185A78B; Wed, 17 May 2023 22:10:25 +0000 (UTC) Received: from localhost (unknown [10.39.192.14]) by smtp.corp.redhat.com (Postfix) with ESMTP id DFC2BC15BA0; Wed, 17 May 2023 22:10:24 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: a3f51616-f4ff-11ed-b22a-6b7b168915f2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684361432; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=N/ldJhRh22XDo67uOMsA8dfc78R1BhZ6UygIAszkpiQ=; b=H+dLBQeNZjT+Ew29XQwEO1Fey19IYsAKrgfSRwQ4aGhQdhgy+rq39djD7y9oy+EBT/1JGE fy786SdEqqG9ViPlsdehabDUauEWoboSZFosd0M3VWCnKKL365tyk50qb6MZrOO1wQwtxC Xlui6DwtefPw8psePEXyT18djal+1ic= X-MC-Unique: lSLG9I1HP4uawS9h9gPBxQ-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: xen-devel@lists.xenproject.org, Julia Suvorova , "Michael S. Tsirkin" , Stefano Stabellini , Stefano Garzarella , Kevin Wolf , Fam Zheng , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Paolo Bonzini , qemu-block@nongnu.org, Paul Durrant , Anthony Perard , Aarushi Mehta , Stefan Hajnoczi , Hanna Reitz Subject: [PATCH 0/6] block: add blk_io_plug_call() API Date: Wed, 17 May 2023 18:10:16 -0400 Message-Id: <20230517221022.325091-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 The existing blk_io_plug() API is not block layer multi-queue friendly because the plug state is per-BlockDriverState. Change blk_io_plug()'s implementation so it is thread-local. This is done by introducing the blk_io_plug_call() function that block drivers use to batch calls while plugged. It is relatively easy to convert block drivers from .bdrv_co_io_plug() to blk_io_plug_call(). Random read 4KB performance with virtio-blk on a host NVMe block device: iodepth iops change vs today 1 45612 -4% 2 87967 +2% 4 129872 +0% 8 171096 -3% 16 194508 -4% 32 208947 -1% 64 217647 +0% 128 229629 +0% The results are within the noise for these benchmarks. This is to be expected because the plugging behavior for a single thread hasn't changed in this patch series, only that the state is thread-local now. The following graph compares several approaches: https://vmsplice.net/~stefan/blk_io_plug-thread-local.png - v7.2.0: before most of the multi-queue block layer changes landed. - with-blk_io_plug: today's post-8.0.0 QEMU. - blk_io_plug-thread-local: this patch series. - no-blk_io_plug: what happens when we simply remove plugging? - call-after-dispatch: what if we integrate plugging into the event loop? I decided against this approach in the end because it's more likely to introduce performance regressions since I/O submission is deferred until the end of the event loop iteration. Aside from the no-blk_io_plug case, which bottlenecks much earlier than the others, we see that all plugging approaches are more or less equivalent in this benchmark. It is also clear that QEMU 8.0.0 has lower performance than 7.2.0. The Ansible playbook, fio results, and a Jupyter notebook are available here: https://github.com/stefanha/qemu-perf/tree/remove-blk_io_plug Stefan Hajnoczi (6): block: add blk_io_plug_call() API block/nvme: convert to blk_io_plug_call() API block/blkio: convert to blk_io_plug_call() API block/io_uring: convert to blk_io_plug_call() API block/linux-aio: convert to blk_io_plug_call() API block: remove bdrv_co_io_plug() API MAINTAINERS | 1 + include/block/block-io.h | 3 - include/block/block_int-common.h | 11 --- include/block/raw-aio.h | 14 --- include/sysemu/block-backend-io.h | 13 +-- block/blkio.c | 40 ++++---- block/block-backend.c | 22 ----- block/file-posix.c | 38 ------- block/io.c | 37 ------- block/io_uring.c | 45 ++++----- block/linux-aio.c | 41 +++----- block/nvme.c | 44 +++------ block/plug.c | 159 ++++++++++++++++++++++++++++++ hw/block/dataplane/xen-block.c | 8 +- hw/block/virtio-blk.c | 4 +- hw/scsi/virtio-scsi.c | 6 +- block/meson.build | 1 + block/trace-events | 5 +- 18 files changed, 236 insertions(+), 256 deletions(-) create mode 100644 block/plug.c