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[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> X-Stat-Signature: zugon5j8tdunoprjwmttxypqqoz65nf6 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 60E8420001DC Received-SPF: none (ziepe.ca>: No applicable sender policy available) receiver=imf01; identity=mailfrom; envelope-from=""; helo=mail-qk1-f169.google.com; client-ip=209.85.222.169 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1612878813-328766 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 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