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=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 C4DEFC64E75 for ; Wed, 18 Nov 2020 09:54:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C9A920706 for ; Wed, 18 Nov 2020 09:54:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JNbmcVCC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726871AbgKRJyR (ORCPT ); Wed, 18 Nov 2020 04:54:17 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:25807 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727521AbgKRJyQ (ORCPT ); Wed, 18 Nov 2020 04:54:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605693255; 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=HkvlidDT7RuDykKbMhHuxkrrFtoJAiVcxN+jntjGpQI=; b=JNbmcVCCFA1sFK3ta/JuHbXfaZO915FmfQ+wxsip9MDYm4zej1Hi1Yfdkc+5wZ8EyI3Znq WG0TM9diIVNGyqhj5tfuC+3rF5lukjZblKV4eHwF6f2nuslSvmqk6Kfs4xw3Bhq0vzVvPl 8L2rCDl3BXWSVl6LLX7t/jsACiTU4gc= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-380-b9GeFlnSMdaS9SvwC6260A-1; Wed, 18 Nov 2020 04:54:12 -0500 X-MC-Unique: b9GeFlnSMdaS9SvwC6260A-1 Received: by mail-wm1-f70.google.com with SMTP id o19so812005wme.2 for ; Wed, 18 Nov 2020 01:54:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=HkvlidDT7RuDykKbMhHuxkrrFtoJAiVcxN+jntjGpQI=; b=XZVWWF/fjkT9DHRNG91dmLtf+2faGsgwHihp8Gs8ztLSMRaN00Ua8xnyrD5mVNJpSX EyEiompsBgESCUenicVUqtdqT0Nbc7HA0RsaiZQTWMTP/SmcoqWySHyFcp5TvH3eHlz4 4JMVmPz155mD6G76XS6W8mZIGUVi2ChU2nS6W1ZJvk87P05El6uhDXBBRURXZsfGP4b8 K1EmMqe1tlpHuEWGpYRwBED4rOipDI7br9dryVvJ1UepRgKXjWNjxphRY/SUj7NC9Tcy zXKK9/CrhlZaY7C0WZAPSpfD27imfxLW+4qnuvAASb+0mGS8J5QIEIQpxEKyHrzNhXhp dNQg== X-Gm-Message-State: AOAM530MfK7Y2UaU2X1gGqLYth4bbMqqvKF2MGqPxNSYxUVIx1nZpD2Z tKtUnLWJ75xVcS1tECCP500HbfLIWmzgjXO5MlXj+trHxh8M9I1kz4Ct0dArhxPHX4WJFdytS9C w8B6f+u5Ap0TtKwW5bz+O4bUY X-Received: by 2002:a7b:c255:: with SMTP id b21mr3661682wmj.72.1605693251508; Wed, 18 Nov 2020 01:54:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJwbXLTxAGOnZyxxbLSLJq6x1VIfry0wChmfEQrkgNC9lF4UHuYFsROS0Onu2BcX6Xl3sE+plg== X-Received: by 2002:a7b:c255:: with SMTP id b21mr3661670wmj.72.1605693251346; Wed, 18 Nov 2020 01:54:11 -0800 (PST) Received: from redhat.com (bzq-109-67-54-78.red.bezeqint.net. [109.67.54.78]) by smtp.gmail.com with ESMTPSA id o13sm2811565wmc.44.2020.11.18.01.54.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Nov 2020 01:54:10 -0800 (PST) Date: Wed, 18 Nov 2020 04:54:07 -0500 From: "Michael S. Tsirkin" To: Mike Christie Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, fam@euphon.net, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, jasowang@redhat.com, pbonzini@redhat.com, virtualization@lists.linux-foundation.org Subject: Re: [PATCH 00/10] vhost/qemu: thread per IO SCSI vq Message-ID: <20201118044620-mutt-send-email-mst@kernel.org> References: <1605223150-10888-1-git-send-email-michael.christie@oracle.com> <20201117164043.GS131917@stefanha-x1.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: target-devel@vger.kernel.org On Tue, Nov 17, 2020 at 01:13:14PM -0600, Mike Christie wrote: > On 11/17/20 10:40 AM, Stefan Hajnoczi wrote: > > On Thu, Nov 12, 2020 at 05:18:59PM -0600, Mike Christie wrote: > >> The following kernel patches were made over Michael's vhost branch: > >> > >> https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost > >> > >> and the vhost-scsi bug fix patchset: > >> > >> https://lore.kernel.org/linux-scsi/20201112170008.GB1555653@stefanha-x1.localdomain/T/#t > >> > >> And the qemu patch was made over the qemu master branch. > >> > >> vhost-scsi currently supports multiple queues with the num_queues > >> setting, but we end up with a setup where the guest's scsi/block > >> layer can do a queue per vCPU and the layers below vhost can do > >> a queue per CPU. vhost-scsi will then do a num_queue virtqueues, > >> but all IO gets set on and completed on a single vhost-scsi thread. > >> After 2 - 4 vqs this becomes a bottleneck. > >> > >> This patchset allows us to create a worker thread per IO vq, so we > >> can better utilize multiple CPUs with the multiple queues. It > >> implments Jason's suggestion to create the initial worker like > >> normal, then create the extra workers for IO vqs with the > >> VHOST_SET_VRING_ENABLE ioctl command added in this patchset. > > > > How does userspace find out the tids and set their CPU affinity? > > > > When we create the worker thread we add it to the device owner's cgroup, > so we end up inheriting those settings like affinity. > > However, are you more asking about finer control like if the guest is > doing mq, and the mq hw queue is bound to cpu0, it would perform > better if we could bind vhost vq's worker thread to cpu0? I think the > problem might is if you are in the cgroup then we can't set a specific > threads CPU affinity to just one specific CPU. So you can either do > cgroups or not. Something we wanted to try for a while is to allow userspace to create threads for us, then specify which vqs it processes. That would address this set of concerns ... -- MST 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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 953E2C56202 for ; Wed, 18 Nov 2020 09:55:21 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9D26620738 for ; Wed, 18 Nov 2020 09:55:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RUKigu6a" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D26620738 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42364 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kfKBL-0001g7-Iv for qemu-devel@archiver.kernel.org; Wed, 18 Nov 2020 04:55:19 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:44912) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kfKAL-00018F-KY for qemu-devel@nongnu.org; Wed, 18 Nov 2020 04:54:17 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:37600) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kfKAJ-0000Xv-UV for qemu-devel@nongnu.org; Wed, 18 Nov 2020 04:54:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605693254; 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=HkvlidDT7RuDykKbMhHuxkrrFtoJAiVcxN+jntjGpQI=; b=RUKigu6a6BcFBb+9KtUs2MQBtHwJr4KuXNmxYWe3NEWhjNXy9O9/VhIdeKsObMTn3qMaAs ANzZjrnCCDJcfAx8WLoaze2LR76rEnHJnnNrVhwJwGtLmsxTSqCv8XmkXZgJsmkR+vLtSF bU4wv05YcHcEz7UOZ5GdsmP2GI8hCFk= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-353-E4dW-bGzMo2_4jJzAoVjjA-1; Wed, 18 Nov 2020 04:54:12 -0500 X-MC-Unique: E4dW-bGzMo2_4jJzAoVjjA-1 Received: by mail-wr1-f72.google.com with SMTP id p16so717461wrx.4 for ; Wed, 18 Nov 2020 01:54:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=HkvlidDT7RuDykKbMhHuxkrrFtoJAiVcxN+jntjGpQI=; b=OvHr0/Jkw5YHFrbNvoy/O2CZCRhzPZK3/NKmjxLYxTZvn/bTYiXcf/K7Uu/Zb7qL3+ uuFEgLDD/nXxDTM8TMcPcK6SQCduSoSxIwpnCyooyusUsAFTegQENkBivVPcXGZzSnUA 2AkxfVelQOodIZpP2V7+OTnrsUtbbHzz8AxD8VDsHOONYTgkIhQNw3MO/yyMCm+jxRLn EP8M8HhME7lotz6UFXsVki3DJKZ6RAPC//leVFvA42ci6pFNzAfh/e8cOcRnZsOdr+I+ pCnv/XXusxdWgJ8lfVPWeJzHRqzfEFFtAjpzShUpyDLss/fhe1/0erSDhfch4VeXCI0r ODAQ== X-Gm-Message-State: AOAM532DsGTJxAqK+J4BEyQXC+GVGOBo9LdCy4WYNO8SIGUsy47afigs pzC5wVazCeO9EiGBEJ8YQSRopcS5VYnQrNdY5ziZor3sBk2HAAVcpHoMfU3Ttnz4pXrRNESgD5d q6kpjT0TkiATDYxM= X-Received: by 2002:a7b:c255:: with SMTP id b21mr3661701wmj.72.1605693251698; Wed, 18 Nov 2020 01:54:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJwbXLTxAGOnZyxxbLSLJq6x1VIfry0wChmfEQrkgNC9lF4UHuYFsROS0Onu2BcX6Xl3sE+plg== X-Received: by 2002:a7b:c255:: with SMTP id b21mr3661670wmj.72.1605693251346; Wed, 18 Nov 2020 01:54:11 -0800 (PST) Received: from redhat.com (bzq-109-67-54-78.red.bezeqint.net. [109.67.54.78]) by smtp.gmail.com with ESMTPSA id o13sm2811565wmc.44.2020.11.18.01.54.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Nov 2020 01:54:10 -0800 (PST) Date: Wed, 18 Nov 2020 04:54:07 -0500 From: "Michael S. Tsirkin" To: Mike Christie Subject: Re: [PATCH 00/10] vhost/qemu: thread per IO SCSI vq Message-ID: <20201118044620-mutt-send-email-mst@kernel.org> References: <1605223150-10888-1-git-send-email-michael.christie@oracle.com> <20201117164043.GS131917@stefanha-x1.localdomain> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/18 00:38:29 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, linux-scsi@vger.kernel.org, jasowang@redhat.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, target-devel@vger.kernel.org, Stefan Hajnoczi , pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Nov 17, 2020 at 01:13:14PM -0600, Mike Christie wrote: > On 11/17/20 10:40 AM, Stefan Hajnoczi wrote: > > On Thu, Nov 12, 2020 at 05:18:59PM -0600, Mike Christie wrote: > >> The following kernel patches were made over Michael's vhost branch: > >> > >> https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost > >> > >> and the vhost-scsi bug fix patchset: > >> > >> https://lore.kernel.org/linux-scsi/20201112170008.GB1555653@stefanha-x1.localdomain/T/#t > >> > >> And the qemu patch was made over the qemu master branch. > >> > >> vhost-scsi currently supports multiple queues with the num_queues > >> setting, but we end up with a setup where the guest's scsi/block > >> layer can do a queue per vCPU and the layers below vhost can do > >> a queue per CPU. vhost-scsi will then do a num_queue virtqueues, > >> but all IO gets set on and completed on a single vhost-scsi thread. > >> After 2 - 4 vqs this becomes a bottleneck. > >> > >> This patchset allows us to create a worker thread per IO vq, so we > >> can better utilize multiple CPUs with the multiple queues. It > >> implments Jason's suggestion to create the initial worker like > >> normal, then create the extra workers for IO vqs with the > >> VHOST_SET_VRING_ENABLE ioctl command added in this patchset. > > > > How does userspace find out the tids and set their CPU affinity? > > > > When we create the worker thread we add it to the device owner's cgroup, > so we end up inheriting those settings like affinity. > > However, are you more asking about finer control like if the guest is > doing mq, and the mq hw queue is bound to cpu0, it would perform > better if we could bind vhost vq's worker thread to cpu0? I think the > problem might is if you are in the cgroup then we can't set a specific > threads CPU affinity to just one specific CPU. So you can either do > cgroups or not. Something we wanted to try for a while is to allow userspace to create threads for us, then specify which vqs it processes. That would address this set of concerns ... -- MST 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=-8.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,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 8197DC64E7A for ; Wed, 18 Nov 2020 09:54:20 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C37102168B for ; Wed, 18 Nov 2020 09:54:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RUKigu6a" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C37102168B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 4369783500; Wed, 18 Nov 2020 09:54:19 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id x9NM4rnyeiWI; Wed, 18 Nov 2020 09:54:18 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id A9A6E832C6; Wed, 18 Nov 2020 09:54:18 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 7974FC0891; Wed, 18 Nov 2020 09:54:18 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 893AAC07FF for ; Wed, 18 Nov 2020 09:54:17 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 76C4C83500 for ; Wed, 18 Nov 2020 09:54:17 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id um9_f14XIzvq for ; Wed, 18 Nov 2020 09:54:16 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 3CE9A832C6 for ; Wed, 18 Nov 2020 09:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605693254; 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=HkvlidDT7RuDykKbMhHuxkrrFtoJAiVcxN+jntjGpQI=; b=RUKigu6a6BcFBb+9KtUs2MQBtHwJr4KuXNmxYWe3NEWhjNXy9O9/VhIdeKsObMTn3qMaAs ANzZjrnCCDJcfAx8WLoaze2LR76rEnHJnnNrVhwJwGtLmsxTSqCv8XmkXZgJsmkR+vLtSF bU4wv05YcHcEz7UOZ5GdsmP2GI8hCFk= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-360-5xFpsERMOterzDmnRFAfcg-1; Wed, 18 Nov 2020 04:54:12 -0500 X-MC-Unique: 5xFpsERMOterzDmnRFAfcg-1 Received: by mail-wr1-f70.google.com with SMTP id w6so713663wrk.1 for ; Wed, 18 Nov 2020 01:54:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=HkvlidDT7RuDykKbMhHuxkrrFtoJAiVcxN+jntjGpQI=; b=ZfNGseevgXXAzcZESnmct2mYLc8OOxqt/kbnUAs8yXOmrlea+ZT7ifzfdqDG9JSUwP uM3iVX3yK2eXH2+EAUG/luNQdoeS+hBEQ/pBpx0WVcHxScjC/Ad4DWze5MSyCLmGUiL3 0tWAnBC4RGKF/WOlYOqpbHvgjfhwSSsUHZzdXIyv/U25jayaLaqhk2ziazhzJuB/mF8q vfdwkXjJ++p61vZwdQxtUgrr2VUljg6fWcoFSrXt3OJKhetBivMqlr5sc6SYfJ3Co8uG FutK2a3Hw4X+aTGX51KvrCAx64SXkaYAxcTutMDnQRkPQ12yXdaOdKxdyXxnKnNbMMAy yvMw== X-Gm-Message-State: AOAM531YZIDUN/MJD/ATf12fpUoDq4J8O4HCl9Ii2q1aJcn+HJ/A2/4N 1+/lEnte348pxbjQRLFK33PrR/ZwXdrMWpD3fKESZcquV60uJ2hEJV6tqJPLyoNoyQpmsTuP3Gg 4u4o3/LrS3IZkVYZSswPx7BWxj1ACxqdeO8VenEURZA== X-Received: by 2002:a7b:c255:: with SMTP id b21mr3661686wmj.72.1605693251510; Wed, 18 Nov 2020 01:54:11 -0800 (PST) X-Google-Smtp-Source: ABdhPJwbXLTxAGOnZyxxbLSLJq6x1VIfry0wChmfEQrkgNC9lF4UHuYFsROS0Onu2BcX6Xl3sE+plg== X-Received: by 2002:a7b:c255:: with SMTP id b21mr3661670wmj.72.1605693251346; Wed, 18 Nov 2020 01:54:11 -0800 (PST) Received: from redhat.com (bzq-109-67-54-78.red.bezeqint.net. [109.67.54.78]) by smtp.gmail.com with ESMTPSA id o13sm2811565wmc.44.2020.11.18.01.54.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Nov 2020 01:54:10 -0800 (PST) Date: Wed, 18 Nov 2020 04:54:07 -0500 From: "Michael S. Tsirkin" To: Mike Christie Subject: Re: [PATCH 00/10] vhost/qemu: thread per IO SCSI vq Message-ID: <20201118044620-mutt-send-email-mst@kernel.org> References: <1605223150-10888-1-git-send-email-michael.christie@oracle.com> <20201117164043.GS131917@stefanha-x1.localdomain> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: fam@euphon.net, linux-scsi@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, target-devel@vger.kernel.org, Stefan Hajnoczi , pbonzini@redhat.com X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Tue, Nov 17, 2020 at 01:13:14PM -0600, Mike Christie wrote: > On 11/17/20 10:40 AM, Stefan Hajnoczi wrote: > > On Thu, Nov 12, 2020 at 05:18:59PM -0600, Mike Christie wrote: > >> The following kernel patches were made over Michael's vhost branch: > >> > >> https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost > >> > >> and the vhost-scsi bug fix patchset: > >> > >> https://lore.kernel.org/linux-scsi/20201112170008.GB1555653@stefanha-x1.localdomain/T/#t > >> > >> And the qemu patch was made over the qemu master branch. > >> > >> vhost-scsi currently supports multiple queues with the num_queues > >> setting, but we end up with a setup where the guest's scsi/block > >> layer can do a queue per vCPU and the layers below vhost can do > >> a queue per CPU. vhost-scsi will then do a num_queue virtqueues, > >> but all IO gets set on and completed on a single vhost-scsi thread. > >> After 2 - 4 vqs this becomes a bottleneck. > >> > >> This patchset allows us to create a worker thread per IO vq, so we > >> can better utilize multiple CPUs with the multiple queues. It > >> implments Jason's suggestion to create the initial worker like > >> normal, then create the extra workers for IO vqs with the > >> VHOST_SET_VRING_ENABLE ioctl command added in this patchset. > > > > How does userspace find out the tids and set their CPU affinity? > > > > When we create the worker thread we add it to the device owner's cgroup, > so we end up inheriting those settings like affinity. > > However, are you more asking about finer control like if the guest is > doing mq, and the mq hw queue is bound to cpu0, it would perform > better if we could bind vhost vq's worker thread to cpu0? I think the > problem might is if you are in the cgroup then we can't set a specific > threads CPU affinity to just one specific CPU. So you can either do > cgroups or not. Something we wanted to try for a while is to allow userspace to create threads for us, then specify which vqs it processes. That would address this set of concerns ... -- MST _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization