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 7DC27C433DB for ; Tue, 9 Feb 2021 13:55:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 31C0464EED for ; Tue, 9 Feb 2021 13:55:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232032AbhBINzK (ORCPT ); Tue, 9 Feb 2021 08:55:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33828 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232049AbhBINyc (ORCPT ); Tue, 9 Feb 2021 08:54:32 -0500 Received: from mail-qk1-x72a.google.com (mail-qk1-x72a.google.com [IPv6:2607:f8b0:4864:20::72a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6788CC061793 for ; Tue, 9 Feb 2021 05:53:33 -0800 (PST) Received: by mail-qk1-x72a.google.com with SMTP id m144so2136517qke.10 for ; Tue, 09 Feb 2021 05:53:33 -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=T8f8DDfwXSd9VRLmEP8P3umzAghI6Kqw6/qy/jeS5Qo=; b=gh04iuWWyfXXLlaV1RWSVt6ZQHHbXgL+7SqTdgohcZssGB7SFCglc2Da1zz58QYygR 9tVoLF0GKpMU5fAKOJUQeZbKmiZNBpriOh6NJ88Z8/8Oiy+02484H0DfDsD9oLpEdCJB iqbllGJHAulzwrFuz8zaWKtRoDWR91pkLeY3goABlW/bNnl7a7ucWFWFLWHoTWeFdCfi E81odK7NiX2mIG23/RyV6fotvVvwHXBJ3/Y6NQ+7HvCiAyAGmRSY3kUdW52i458n5RX4 NyglMvima/h3o9mIMHNuMfUszee7pZjUtNzI0o4O78Zz7zTTtKPysaZeIPpMxYD972RH nQ7Q== 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=T8f8DDfwXSd9VRLmEP8P3umzAghI6Kqw6/qy/jeS5Qo=; b=KvqjKDg2Xm2miGXJcaAgeLakw+VCay1ao94WgP1goI3uj29S9eZ5iPRvds2dlClF2T zivsBgM0y0CFTPYDUTtw+gkp5WsrRyqTaI2rFRqPc+mrbmg4Ul0NeWe625JEKgxbPLSe 4H+rhi2mv63K5onjS5t97HegFwsVQ3YWb8IlwuuT6FUXXMjSgTz0zWXe7dtzQ4R82tyu emDWsvndrM9d/7jteJdZ63kfkPTDFbLEEHCuB8yrrKn4nBvXa3hPz9pRKWguwkLLIumL qWgqX0KNKImTDOIwIlqhbCA9bXgfLcnRDCUx/3TTqLPlrqvG7gpvzGkceH/FDjpvrYO3 9cIg== X-Gm-Message-State: AOAM531LgEZtzREIHKg+ykNnRs5OfwhUjLZiI70FRtCO7loZ53YZxcg4 Ay0GAyw3qedbwnaufoVtOWx7AA== X-Google-Smtp-Source: ABdhPJx3et279cgNvk+uqR894IQLoOIQFoSZDGEjQvDKhVHg09126LSd7Y8VSphbQdCDRlOdHVR86w== X-Received: by 2002:ae9:e80e:: with SMTP id a14mr11633708qkg.103.1612878812715; Tue, 09 Feb 2021 05:53:32 -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 d16sm17820271qka.44.2021.02.09.05.53.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Feb 2021 05:53:32 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l9TSN-005RZu-ON; Tue, 09 Feb 2021 09:53:31 -0400 Date: Tue, 9 Feb 2021 09:53:31 -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: <20210209135331.GF4718@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0868d209d7424942a46d1238674cf75d@hisilicon.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 09, 2021 at 03:01:42AM +0000, Song Bao Hua (Barry Song) wrote: > On the other hand, wouldn't it be the benefit of hardware accelerators > to have a lower and more stable latency zip/encryption than CPU? No, I don't think so. If this is an important problem then it should apply equally to CPU and IO jitter. Honestly I find the idea that occasional migration jitters CPU and DMA to not be very compelling. Such specialized applications should allocate special pages to avoid this, not adding an API to be able to lock down any page Jason