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=-7.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 A662DC7618B for ; Wed, 24 Jul 2019 12:28:54 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 791AE21BF6 for ; Wed, 24 Jul 2019 12:28:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="YZo8/yDo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 791AE21BF6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 2903DE47; Wed, 24 Jul 2019 12:28:54 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 500C3D56 for ; Wed, 24 Jul 2019 12:28:52 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id EE857FE for ; Wed, 24 Jul 2019 12:28:51 +0000 (UTC) Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2983221BF6; Wed, 24 Jul 2019 12:28:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563971331; bh=upEYkhnwePTSx1iWqXBTxA1naAhaVRCl26Y3GCufzRU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YZo8/yDo74N6v7UNWdGB3e6Re9WGLBI5vscvlQlx2+YxtLjFZGPg5RToSTaL0RugG 4q81mxbUy4EBa6d6gUs/uRnOclIS0Rdobz8iScJD0t2aWU7cLf5DkjIWj9ZRJ7pXw4 M6JlXRVp92/Dsc29est4NhN9pve0hK03Ohutqhxw= Date: Wed, 24 Jul 2019 13:28:47 +0100 From: Will Deacon To: Ganapatrao Kulkarni Subject: Re: [RFC PATCH v2 00/19] Try to reduce lock contention on the SMMUv3 command queue Message-ID: <20190724122846.5mynuxkm3rgipxhp@willie-the-truck> References: <20190711171927.28803-1-will@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Cc: Vijay Kilary , Jean-Philippe Brucker , Jon Masters , Jan Glauber , Alex Williamson , iommu@lists.linux-foundation.org, Jayachandran Chandrasekharan Nair , Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Fri, Jul 19, 2019 at 09:55:39AM +0530, Ganapatrao Kulkarni wrote: > On Thu, Jul 11, 2019 at 10:58 PM Will Deacon wrote: > > This is a significant rework of the RFC I previously posted here: > > > > https://lkml.kernel.org/r/20190611134603.4253-1-will.deacon@arm.com > > > > But this time, it looks like it might actually be worthwhile according > > to my perf profiles, where __iommu_unmap() falls a long way down the > > profile for a multi-threaded netperf run. I'm still relying on others to > > confirm this is useful, however. > > > > Some of the changes since last time are: > > > > * Support for constructing and submitting a list of commands in the > > driver > > > > * Numerous changes to the IOMMU and io-pgtable APIs so that we can > > submit commands in batches > > > > * Removal of cmpxchg() from cmdq_shared_lock() fast-path > > > > * Code restructuring and cleanups > > > > This current applies against my iommu/devel branch that Joerg has pulled > > for 5.3. If you want to test it out, I've put everything here: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=iommu/cmdq > > > > Feedback welcome. I appreciate that we're in the merge window, but I > > wanted to get this on the list for people to look at as an RFC. > > I have tried branch iommu/cmdq on ThunderX2. I do see there is drastic > reduction in CPU bandwidth consumption(from 15 to 20% to 1 to 2% in > perf top) from SMMU CMDQ helper functions, when I run iperf with more > than 64 clients(-P 64). However I have not noticed any measurable > performance improvement in iperf results. IMO, this might/should help > in performance improvement of IO intensive workloads. > > FWIW, you can add, > Tested-by: Ganapatrao Kulkarni Brilliant, thanks. Your measurements reflect mine in that I can saturate the NICs I have access to regardless of these changes, but the CPU time is drastically reduced. Will _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu