From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB5DDC433F5 for ; Thu, 23 Sep 2021 15:37:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A40361019 for ; Thu, 23 Sep 2021 15:37:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242031AbhIWPjX (ORCPT ); Thu, 23 Sep 2021 11:39:23 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:54690 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241995AbhIWPjX (ORCPT ); Thu, 23 Sep 2021 11:39:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632411471; 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: in-reply-to:in-reply-to:references:references; bh=AOSJdORroeY+L8lMWoT/k2QmeHNRD0UxneSQj0X18oA=; b=SGKrJ72+QbZsCz2Wc4n0VFxztRC18W23zMWtMguGb39HpIuvz5HGcKUdCV3S8HhStgEZYg 41it/F7g6noEjsPXtm6KfN0lK8nBfW3EuIdEc5BOVI59svTQRH4x2BpSxUiItGW5ltxRvU blViAp4dnPtzuECSNu3yBzeIv4pIxzc= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-362-J73WndtAMrWCZNcion-_4w-1; Thu, 23 Sep 2021 11:37:49 -0400 X-MC-Unique: J73WndtAMrWCZNcion-_4w-1 Received: by mail-ed1-f72.google.com with SMTP id b7-20020a50e787000000b003d59cb1a923so7249247edn.5 for ; Thu, 23 Sep 2021 08:37:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=AOSJdORroeY+L8lMWoT/k2QmeHNRD0UxneSQj0X18oA=; b=0z5nnUdTut7SKy2HwdRr3+xB4lg/Xv7PMQCR5j1/5DUGjJjoBIl58cYP6bQwLgjk3X DgscHIVH8MQaJakrB+mhPQVBGz0wXUJnosiKT7ZUpfA/Wr3AgWpYDgn0dZFYfXTBcKH4 gA15vmwVHBrRAs14F+QcjPWkbOi/kh6FTYbZllVAeEErpMKRvkFIVklHGEZKRdXZPIf+ 6Rh9FzAf+zw6zmbLBNKItXQhQjSjS0LAnWhorq8A7JnuFB/Guo44XpW960snUSprArb8 loVZO4cUqRBrgCHRn4z0SfUdwTrNh5O+ZVI+6W8SpNDX/JICzx6yxTWt74lJ/k3ZY+9s nifw== X-Gm-Message-State: AOAM533wAtfTFcQ0PLABMPh+6daCipJu4aEW2FaKlL5BG2sNQN8Qudq+ fMqqJk/IKPn6g/6zA/3vrKuLHD4UofWdNOetr6FLS0/1Za+bSGeIYDQKsCjPB71LXx6aXCauCpI r58/g3YMTAcZ1k7Fx1DGrDyk= X-Received: by 2002:a50:d84c:: with SMTP id v12mr6078249edj.201.1632411468257; Thu, 23 Sep 2021 08:37:48 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy8DaBe4I+LkOVyQLu6cfQoWkqvgiBaOR5+1qn3bcBVQnRix8ZU/+hekqhUIynodgC4qCiRWw== X-Received: by 2002:a50:d84c:: with SMTP id v12mr6078219edj.201.1632411468054; Thu, 23 Sep 2021 08:37:48 -0700 (PDT) Received: from redhat.com ([2.55.11.56]) by smtp.gmail.com with ESMTPSA id d3sm3738711edv.87.2021.09.23.08.37.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Sep 2021 08:37:47 -0700 (PDT) Date: Thu, 23 Sep 2021 11:37:42 -0400 From: "Michael S. Tsirkin" To: Max Gurtovoy Cc: Stefan Hajnoczi , Jens Axboe , hch@infradead.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, israelr@nvidia.com, nitzanc@nvidia.com, oren@nvidia.com, linux-block@vger.kernel.org Subject: Re: [PATCH v3 1/1] virtio-blk: avoid preallocating big SGL for data Message-ID: <20210923113644-mutt-send-email-mst@kernel.org> References: <20210901131434.31158-1-mgurtovoy@nvidia.com> <692f8e81-8585-1d39-e7a4-576ae01438a1@nvidia.com> <56cf84e2-fec0-08e8-0a47-24bb1df71883@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56cf84e2-fec0-08e8-0a47-24bb1df71883@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org OK by me. Acked-by: Michael S. Tsirkin I will queue it for the next kernel. Thanks! On Thu, Sep 23, 2021 at 04:40:56PM +0300, Max Gurtovoy wrote: > Hi MST/Jens, > > Do we need more review here or are we ok with the code and the test matrix ? > > If we're ok, we need to decide if this goes through virtio PR or block PR. > > Cheers, > > -Max. > > On 9/14/2021 3:22 PM, Stefan Hajnoczi wrote: > > On Mon, Sep 13, 2021 at 05:50:21PM +0300, Max Gurtovoy wrote: > > > On 9/6/2021 6:09 PM, Stefan Hajnoczi wrote: > > > > On Wed, Sep 01, 2021 at 04:14:34PM +0300, Max Gurtovoy wrote: > > > > > No need to pre-allocate a big buffer for the IO SGL anymore. If a device > > > > > has lots of deep queues, preallocation for the sg list can consume > > > > > substantial amounts of memory. For HW virtio-blk device, nr_hw_queues > > > > > can be 64 or 128 and each queue's depth might be 128. This means the > > > > > resulting preallocation for the data SGLs is big. > > > > > > > > > > Switch to runtime allocation for SGL for lists longer than 2 entries. > > > > > This is the approach used by NVMe drivers so it should be reasonable for > > > > > virtio block as well. Runtime SGL allocation has always been the case > > > > > for the legacy I/O path so this is nothing new. > > > > > > > > > > The preallocated small SGL depends on SG_CHAIN so if the ARCH doesn't > > > > > support SG_CHAIN, use only runtime allocation for the SGL. > > > > > > > > > > Re-organize the setup of the IO request to fit the new sg chain > > > > > mechanism. > > > > > > > > > > No performance degradation was seen (fio libaio engine with 16 jobs and > > > > > 128 iodepth): > > > > > > > > > > IO size IOPs Rand Read (before/after) IOPs Rand Write (before/after) > > > > > -------- --------------------------------- ---------------------------------- > > > > > 512B 318K/316K 329K/325K > > > > > > > > > > 4KB 323K/321K 353K/349K > > > > > > > > > > 16KB 199K/208K 250K/275K > > > > > > > > > > 128KB 36K/36.1K 39.2K/41.7K > > > > I ran fio randread benchmarks with 4k, 16k, 64k, and 128k at iodepth 1, > > > > 8, and 64 on two vCPUs. The results look fine, there is no significant > > > > regression. > > > > > > > > iodepth=1 and iodepth=64 are very consistent. For some reason the > > > > iodepth=8 has significant variance but I don't think it's the fault of > > > > this patch. > > > > > > > > Fio results and the Jupyter notebook export are available here (check > > > > out benchmark.html to see the graphs): > > > > > > > > https://gitlab.com/stefanha/virt-playbooks/-/tree/virtio-blk-sgl-allocation-benchmark/notebook > > > > > > > > Guest: > > > > - Fedora 34 > > > > - Linux v5.14 > > > > - 2 vCPUs (pinned), 4 GB RAM (single host NUMA node) > > > > - 1 IOThread (pinned) > > > > - virtio-blk aio=native,cache=none,format=raw > > > > - QEMU 6.1.0 > > > > > > > > Host: > > > > - RHEL 8.3 > > > > - Linux 4.18.0-240.22.1.el8_3.x86_64 > > > > - Intel(R) Xeon(R) Silver 4214 CPU @ 2.20GHz > > > > - Intel Optane DC P4800X > > > > > > > > Stefan > > > Thanks, Stefan. > > > > > > Would you like me to add some of the results in my commit msg ? or Tested-By > > > sign ? > > Thanks, there's no need to change the commit description. > > > > Reviewed-by: Stefan Hajnoczi > > Tested-by: Stefan Hajnoczi