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[142.162.115.133]) by smtp.gmail.com with ESMTPSA id j46sm1828038qtk.1.2021.02.10.10.04.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Feb 2021 10:04:06 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l9tqP-0068Ck-JW; Wed, 10 Feb 2021 14:04:05 -0400 Date: Wed, 10 Feb 2021 14:04:05 -0400 From: Jason Gunthorpe To: "Song Bao Hua (Barry Song)" Cc: David Hildenbrand , "Wangzhou (B)" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-mm@kvack.org" , "linux-arm-kernel@lists.infradead.org" , "linux-api@vger.kernel.org" , Andrew Morton , Alexander Viro , "gregkh@linuxfoundation.org" , "kevin.tian@intel.com" , "jean-philippe@linaro.org" , "eric.auger@redhat.com" , "Liguozhu (Kenneth)" , "zhangfei.gao@linaro.org" , "chensihang (A)" Subject: Re: [RFC PATCH v3 1/2] mempinfd: Add new syscall to provide memory pin Message-ID: <20210210180405.GP4718@ziepe.ca> References: <1612685884-19514-1-git-send-email-wangzhou1@hisilicon.com> <1612685884-19514-2-git-send-email-wangzhou1@hisilicon.com> <20210208183348.GV4718@ziepe.ca> <0dca000a6cd34d8183062466ba7d6eaf@hisilicon.com> <20210208213023.GZ4718@ziepe.ca> <0868d209d7424942a46d1238674cf75d@hisilicon.com> <20210209135331.GF4718@ziepe.ca> <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 09, 2021 at 10:22:47PM +0000, Song Bao Hua (Barry Song) wrote: > The problem is that SVA declares we can use any memory of a process > to do I/O. And in real scenarios, we are unable to customize most > applications to make them use the pool. So we are looking for some > extension generically for applications such as Nginx, Ceph. But those applications will suffer jitter even if their are using CPU to do the same work. I fail to see why adding an accelerator suddenly means the application owner will care about jitter introduced by migration/etc. Again in proper SVA it should be quite unlikely to take a fault caused by something like migration, on the same likelyhood as the CPU. If things are faulting so much this is a problem then I think it is a system level problem with doing too much page motion. Jason 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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 6722DC433E0 for ; Wed, 10 Feb 2021 18:04:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1A04C64EDA for ; Wed, 10 Feb 2021 18:04:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1A04C64EDA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8FAA06B0075; Wed, 10 Feb 2021 13:04:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8846E6B007B; Wed, 10 Feb 2021 13:04:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 725296B007D; Wed, 10 Feb 2021 13:04:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0059.hostedemail.com [216.40.44.59]) by kanga.kvack.org (Postfix) with ESMTP id 59ACD6B0075 for ; Wed, 10 Feb 2021 13:04:09 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 2A9F311230 for ; Wed, 10 Feb 2021 18:04:09 +0000 (UTC) X-FDA: 77803132218.25.snow94_451135527612 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id F13B01801AB44 for ; Wed, 10 Feb 2021 18:04:08 +0000 (UTC) X-HE-Tag: snow94_451135527612 X-Filterd-Recvd-Size: 5117 Received: from mail-qk1-f169.google.com (mail-qk1-f169.google.com [209.85.222.169]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Wed, 10 Feb 2021 18:04:08 +0000 (UTC) Received: by mail-qk1-f169.google.com with SMTP id q85so2537270qke.8 for ; Wed, 10 Feb 2021 10:04:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=fn4OROpwcMvlPuFG0mr8IX6FA+jFG3+mu5LheKqkXo0=; b=iPiobhPwf6KAYITESCCZiytaCFr72WzGFqO5Krxg583eeHZJJswee2IVlHJuHVFk51 hUWKXhD6qUJQZ9akF+hoJ0SBMSynl89auCrmXzGqpwVR8TTrOwLCakALhhncmc/31KKO w5cpzUSnU3cZ2kGIXac5w3JXTOg1uG5uRsLrYjb0siJVoMpiahMmcfRtKm3eynVnB77A qq+aY8bUIaIHuFg9y9XapEOc7TwpMRqaDXdJ3B4ZZnVPlh2aFbugjNjlrCgAvTvQbuiv 8rQnonVEPXVhg74c+0AallmP+gLOo6xaV7ay5dZwzBUgW+9vToCfuh+GOlDUSGRfOBpQ oKbA== 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=fn4OROpwcMvlPuFG0mr8IX6FA+jFG3+mu5LheKqkXo0=; b=ob3eCyom4SG3PYzE6kBv+2Qs9cEndv7fOMnWpmQcLR//BiaSgoP0wd3ZtPSQ8rN2rH /VNbOr3011i0tZYKFymb0I/dTN8MYuEaXMtw4RL2xKuBY1IaEu9gtMbxrrbGiykmvcRm uFXYgDHQrJolLf3xrfYHHAeSiDkY6MglISYGIJvFEOAmtCe9punhqGXt111thyX+6DiY imQ1nE0HN1aiGCUZFaqpTOi6gj7DLwvR9FVl3QyJbzByTGg1CcxMlHG3fjkkT5JGaQ8L 6qz2YJXLnVnY4bCG7F0YupTclvakhnnijkAgq039nnzoqY+cS5C0XOxYgVNxUATwQDPv q5qA== X-Gm-Message-State: AOAM530NDphvaHhJnwARnGsxYmQbugHY9zMVexuE2rNUBnWxqgOmQRTZ Tq6GS+P654tsTeXk6P0uHRwyeA== X-Google-Smtp-Source: ABdhPJyf3nDN5LDKdSKYE48IyBU6XZ6U0kgAEb02GCT83X4HerFr5BHXcsaa/epIdRev4YLuR0GG8A== X-Received: by 2002:a37:6f01:: with SMTP id k1mr4613354qkc.252.1612980247944; Wed, 10 Feb 2021 10:04:07 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-115-133.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.115.133]) by smtp.gmail.com with ESMTPSA id j46sm1828038qtk.1.2021.02.10.10.04.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Feb 2021 10:04:06 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l9tqP-0068Ck-JW; Wed, 10 Feb 2021 14:04:05 -0400 Date: Wed, 10 Feb 2021 14:04:05 -0400 From: Jason Gunthorpe To: "Song Bao Hua (Barry Song)" Cc: David Hildenbrand , "Wangzhou (B)" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-mm@kvack.org" , "linux-arm-kernel@lists.infradead.org" , "linux-api@vger.kernel.org" , Andrew Morton , Alexander Viro , "gregkh@linuxfoundation.org" , "kevin.tian@intel.com" , "jean-philippe@linaro.org" , "eric.auger@redhat.com" , "Liguozhu (Kenneth)" , "zhangfei.gao@linaro.org" , "chensihang (A)" Subject: Re: [RFC PATCH v3 1/2] mempinfd: Add new syscall to provide memory pin Message-ID: <20210210180405.GP4718@ziepe.ca> References: <1612685884-19514-1-git-send-email-wangzhou1@hisilicon.com> <1612685884-19514-2-git-send-email-wangzhou1@hisilicon.com> <20210208183348.GV4718@ziepe.ca> <0dca000a6cd34d8183062466ba7d6eaf@hisilicon.com> <20210208213023.GZ4718@ziepe.ca> <0868d209d7424942a46d1238674cf75d@hisilicon.com> <20210209135331.GF4718@ziepe.ca> <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Feb 09, 2021 at 10:22:47PM +0000, Song Bao Hua (Barry Song) wrote: > The problem is that SVA declares we can use any memory of a process > to do I/O. And in real scenarios, we are unable to customize most > applications to make them use the pool. So we are looking for some > extension generically for applications such as Nginx, Ceph. But those applications will suffer jitter even if their are using CPU to do the same work. I fail to see why adding an accelerator suddenly means the application owner will care about jitter introduced by migration/etc. Again in proper SVA it should be quite unlikely to take a fault caused by something like migration, on the same likelyhood as the CPU. If things are faulting so much this is a problem then I think it is a system level problem with doing too much page motion. Jason 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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 E323CC433E6 for ; Wed, 10 Feb 2021 18:04:26 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 7E50764DB1 for ; Wed, 10 Feb 2021 18:04:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E50764DB1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 03E4C6F78A for ; Wed, 10 Feb 2021 18:04:25 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id S1CHmZ3S3zGJ for ; Wed, 10 Feb 2021 18:04:22 +0000 (UTC) Received: by smtp3.osuosl.org (Postfix, from userid 1001) id D55246F70E; Wed, 10 Feb 2021 18:04:21 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp3.osuosl.org (Postfix) with ESMTP id AA9786F69E; Wed, 10 Feb 2021 18:04:15 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 833FDC0891; Wed, 10 Feb 2021 18:04:15 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 687DDC013A for ; Wed, 10 Feb 2021 18:04:13 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 562D1874C5 for ; Wed, 10 Feb 2021 18:04:13 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id v5DJjFw8fdAI for ; Wed, 10 Feb 2021 18:04:09 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mail-qk1-f173.google.com (mail-qk1-f173.google.com [209.85.222.173]) by hemlock.osuosl.org (Postfix) with ESMTPS id 0A058874C3 for ; Wed, 10 Feb 2021 18:04:08 +0000 (UTC) Received: by mail-qk1-f173.google.com with SMTP id l27so2524408qki.9 for ; Wed, 10 Feb 2021 10:04:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=fn4OROpwcMvlPuFG0mr8IX6FA+jFG3+mu5LheKqkXo0=; b=iPiobhPwf6KAYITESCCZiytaCFr72WzGFqO5Krxg583eeHZJJswee2IVlHJuHVFk51 hUWKXhD6qUJQZ9akF+hoJ0SBMSynl89auCrmXzGqpwVR8TTrOwLCakALhhncmc/31KKO w5cpzUSnU3cZ2kGIXac5w3JXTOg1uG5uRsLrYjb0siJVoMpiahMmcfRtKm3eynVnB77A qq+aY8bUIaIHuFg9y9XapEOc7TwpMRqaDXdJ3B4ZZnVPlh2aFbugjNjlrCgAvTvQbuiv 8rQnonVEPXVhg74c+0AallmP+gLOo6xaV7ay5dZwzBUgW+9vToCfuh+GOlDUSGRfOBpQ oKbA== 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=fn4OROpwcMvlPuFG0mr8IX6FA+jFG3+mu5LheKqkXo0=; b=hEsGrNfXNjTKdilRC2VBhorqGWfhMcSQAbVcKg9Z1uGScEf8rGt2vlgAHdaZsUANCR DyumlM9xJrU7qS2p9ZqDQjICQUAZpQ6PY6ac1KUo4YVe5cW0cxa4OQc9UjHKJ7bAaLj5 VA9rESb2ynEv9ltkzsToNqS+gO2eCbnppzP12p7vTZDK3BvebirAxk8qu9k1ZeDqButc ypOTHz2tSrs2CykSCzSEbqzLFVA3DSA9kN76YF0ybiOURcqxf5b1UmTTBf/kGntIDO5b 8nQM3AQ1YhyKcb+eYO1oR2py8Xe747eVJT0n3JJZaBA34JJmn3fIWTNEG61w0zYxKwYl hTlA== X-Gm-Message-State: AOAM533D+8bfFuPYduyJW2pzTlnC4O5yzybmrObjHtxeyz3kCutY8npj vkji7pKcvGkthFE4wzEAgfdWRA== X-Google-Smtp-Source: ABdhPJyf3nDN5LDKdSKYE48IyBU6XZ6U0kgAEb02GCT83X4HerFr5BHXcsaa/epIdRev4YLuR0GG8A== X-Received: by 2002:a37:6f01:: with SMTP id k1mr4613354qkc.252.1612980247944; Wed, 10 Feb 2021 10:04:07 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-115-133.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.115.133]) by smtp.gmail.com with ESMTPSA id j46sm1828038qtk.1.2021.02.10.10.04.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Feb 2021 10:04:06 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l9tqP-0068Ck-JW; Wed, 10 Feb 2021 14:04:05 -0400 Date: Wed, 10 Feb 2021 14:04:05 -0400 From: Jason Gunthorpe To: "Song Bao Hua (Barry Song)" Subject: Re: [RFC PATCH v3 1/2] mempinfd: Add new syscall to provide memory pin Message-ID: <20210210180405.GP4718@ziepe.ca> References: <1612685884-19514-1-git-send-email-wangzhou1@hisilicon.com> <1612685884-19514-2-git-send-email-wangzhou1@hisilicon.com> <20210208183348.GV4718@ziepe.ca> <0dca000a6cd34d8183062466ba7d6eaf@hisilicon.com> <20210208213023.GZ4718@ziepe.ca> <0868d209d7424942a46d1238674cf75d@hisilicon.com> <20210209135331.GF4718@ziepe.ca> <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> Cc: "jean-philippe@linaro.org" , "kevin.tian@intel.com" , "chensihang \(A\)" , David Hildenbrand , "linux-api@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-mm@kvack.org" , Alexander Viro , "gregkh@linuxfoundation.org" , "zhangfei.gao@linaro.org" , Andrew Morton , "Liguozhu \(Kenneth\)" , "linux-arm-kernel@lists.infradead.org" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 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 Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Tue, Feb 09, 2021 at 10:22:47PM +0000, Song Bao Hua (Barry Song) wrote: > The problem is that SVA declares we can use any memory of a process > to do I/O. And in real scenarios, we are unable to customize most > applications to make them use the pool. So we are looking for some > extension generically for applications such as Nginx, Ceph. But those applications will suffer jitter even if their are using CPU to do the same work. I fail to see why adding an accelerator suddenly means the application owner will care about jitter introduced by migration/etc. Again in proper SVA it should be quite unlikely to take a fault caused by something like migration, on the same likelyhood as the CPU. If things are faulting so much this is a problem then I think it is a system level problem with doing too much page motion. Jason _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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=-4.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 52967C433DB for ; Wed, 10 Feb 2021 18:05:21 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 13AC064DB1 for ; Wed, 10 Feb 2021 18:05:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13AC064DB1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FIO75pd9I8YoAuNLdxBbYv7oKiTGnQZVs+3JV8A62Kw=; b=gx39Q/1L5T4sRWzYFr2ygr8cA GAvTY458uyne4yXrXcfcUPe52onu8sAXfbBc9iNRkYhHyGB8hrj9uEUCZd6LA0n/dfvVcb3GG0Erk RG1lHswxvkCsfAGHTe9UrG4aykQ6QiJaYkK3HwgRFfao8Lf3zOlkfosYEXOefvwnHUSl2xjieCIoH zxMymRgBHP4ckMFIAGk/S1iOdGHEuaeu35nS/rGKS14bM9hxh11W+OsbeOaJc7H6V1Xx1Hxxz6yQV YooJkPv3ZuT8eK+IZniLKUrTV2S69dbEg25hufVHLWL3Os45fcwgFSpq4GkwIU42sFJ3yq3oVY6Jk LHVcwLT6w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l9tqb-00028k-SC; Wed, 10 Feb 2021 18:04:17 +0000 Received: from mail-qk1-x72b.google.com ([2607:f8b0:4864:20::72b]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l9tqT-00025w-UD for linux-arm-kernel@lists.infradead.org; Wed, 10 Feb 2021 18:04:15 +0000 Received: by mail-qk1-x72b.google.com with SMTP id b14so2570032qkk.0 for ; Wed, 10 Feb 2021 10:04:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=fn4OROpwcMvlPuFG0mr8IX6FA+jFG3+mu5LheKqkXo0=; b=iPiobhPwf6KAYITESCCZiytaCFr72WzGFqO5Krxg583eeHZJJswee2IVlHJuHVFk51 hUWKXhD6qUJQZ9akF+hoJ0SBMSynl89auCrmXzGqpwVR8TTrOwLCakALhhncmc/31KKO w5cpzUSnU3cZ2kGIXac5w3JXTOg1uG5uRsLrYjb0siJVoMpiahMmcfRtKm3eynVnB77A qq+aY8bUIaIHuFg9y9XapEOc7TwpMRqaDXdJ3B4ZZnVPlh2aFbugjNjlrCgAvTvQbuiv 8rQnonVEPXVhg74c+0AallmP+gLOo6xaV7ay5dZwzBUgW+9vToCfuh+GOlDUSGRfOBpQ oKbA== 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=fn4OROpwcMvlPuFG0mr8IX6FA+jFG3+mu5LheKqkXo0=; b=IRIUbmFaKh5waQDF7ZjG2SbSVsu5uz7UEif+kmAqLXTvvr+LR1THH4usBKnuKFzQho Jsfk68eZbg26Ylx9VyuOPD8DKj2q8szRBm7WR9V4aMJ4+NE71Rq0IGG7Ni9JxpmmJ9V8 eNvV+bl/ZSnLA0ciKb65R3o3QTHsU3fJjeU/etE4BlJypIayZnmUoQVBkh7L6XmqxJ71 yWf9eEfnU0hTJoGFj8O1QXpxvc1LR6xgIocjhCOEVihyQvERXEPUZBLhFgYZiEBGIC2M YiigR0Kvh8Nx/8ZFLkJyW2YNs9OaTQY0cCpgKPlQxEk91lt3W8J6PNZSfiPoJaPjDLJS XHOw== X-Gm-Message-State: AOAM532XS5nFiZJquOpu6o6TqdbZZCwFy4Q4ekY3frYT9U6wJxt0Uvg6 XlW0tdR9JV+XXIxio7/zWXknKg== X-Google-Smtp-Source: ABdhPJyf3nDN5LDKdSKYE48IyBU6XZ6U0kgAEb02GCT83X4HerFr5BHXcsaa/epIdRev4YLuR0GG8A== X-Received: by 2002:a37:6f01:: with SMTP id k1mr4613354qkc.252.1612980247944; Wed, 10 Feb 2021 10:04:07 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-115-133.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.115.133]) by smtp.gmail.com with ESMTPSA id j46sm1828038qtk.1.2021.02.10.10.04.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Feb 2021 10:04:06 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l9tqP-0068Ck-JW; Wed, 10 Feb 2021 14:04:05 -0400 Date: Wed, 10 Feb 2021 14:04:05 -0400 From: Jason Gunthorpe To: "Song Bao Hua (Barry Song)" Subject: Re: [RFC PATCH v3 1/2] mempinfd: Add new syscall to provide memory pin Message-ID: <20210210180405.GP4718@ziepe.ca> References: <1612685884-19514-1-git-send-email-wangzhou1@hisilicon.com> <1612685884-19514-2-git-send-email-wangzhou1@hisilicon.com> <20210208183348.GV4718@ziepe.ca> <0dca000a6cd34d8183062466ba7d6eaf@hisilicon.com> <20210208213023.GZ4718@ziepe.ca> <0868d209d7424942a46d1238674cf75d@hisilicon.com> <20210209135331.GF4718@ziepe.ca> <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <2527b4ac8df14fa1b427bef65dace719@hisilicon.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210210_130411_247006_38677A41 X-CRM114-Status: GOOD ( 14.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "jean-philippe@linaro.org" , "kevin.tian@intel.com" , "chensihang \(A\)" , David Hildenbrand , "linux-api@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-mm@kvack.org" , "Wangzhou \(B\)" , Alexander Viro , "eric.auger@redhat.com" , "gregkh@linuxfoundation.org" , "zhangfei.gao@linaro.org" , Andrew Morton , "Liguozhu \(Kenneth\)" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Feb 09, 2021 at 10:22:47PM +0000, Song Bao Hua (Barry Song) wrote: > The problem is that SVA declares we can use any memory of a process > to do I/O. And in real scenarios, we are unable to customize most > applications to make them use the pool. So we are looking for some > extension generically for applications such as Nginx, Ceph. But those applications will suffer jitter even if their are using CPU to do the same work. I fail to see why adding an accelerator suddenly means the application owner will care about jitter introduced by migration/etc. Again in proper SVA it should be quite unlikely to take a fault caused by something like migration, on the same likelyhood as the CPU. If things are faulting so much this is a problem then I think it is a system level problem with doing too much page motion. Jason _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel