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[192.41.125.253]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4923fc47b48sm82606645e9.0.2026.06.19.09.32.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Jun 2026 09:32:02 -0700 (PDT) Date: Fri, 19 Jun 2026 17:32:01 +0100 From: Karim Manaouil To: Shivank Garg Cc: akpm@linux-foundation.org, david@kernel.org, kinseyho@google.com, weixugc@google.com, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, willy@infradead.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, dave@stgolabs.net, Jonathan.Cameron@huawei.com, rkodsara@amd.com, vkoul@kernel.org, bharata@amd.com, sj@kernel.org, rientjes@google.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, dave.hansen@intel.com, hannes@cmpxchg.org, jhubbard@nvidia.com, peterx@redhat.com, riel@surriel.com, shakeel.butt@linux.dev, stalexan@redhat.com, tj@kernel.org, nifan.cxl@gmail.com, jic23@kernel.org, aneesh.kumar@kernel.org, nathan.lynch@amd.com, Frank.li@nxp.com, djbw@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 6/7] drivers/migrate_offload: add DMA batch copy driver (dcbm) Message-ID: <20260619163201.ldbjaqcphke3fcvg@wrangler> References: <20260428155043.39251-2-shivankg@amd.com> <20260428155043.39251-14-shivankg@amd.com> <20260619160725.lfcxrbj5go67qy6u@wrangler> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260619160725.lfcxrbj5go67qy6u@wrangler> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 78D86C0002 X-Stat-Signature: 9h3gzgjj7go88n5r6u1o3q3sf8sg3o57 X-Rspam-User: X-HE-Tag: 1781886724-657942 X-HE-Meta: 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 +nMVrwSJ 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 19, 2026 at 05:07:25PM +0100, Karim Manaouil wrote: > Btw, waiting for an interrupt adds massive scheduling overhead. If we > also add the logic above, it'll get even worse. In my measurements, this > can easily add up to 6ms, by which CPU page copy have easily completed > the entire copy, which again adds to the list of latency concerns I > raised in my other reply. Sorry, I meant 6us. -- ~karim