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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-3a6f987e20asm30995265ab.56.2024.11.13.12.12.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Nov 2024 12:12:43 -0800 (PST) Date: Wed, 13 Nov 2024 15:12:40 -0500 From: Peter Xu To: David Hildenbrand Cc: Yong Huang , qemu-devel@nongnu.org, Fabiano Rosas , Wei Wang , "Michael S . Tsirkin" Subject: Re: [PATCH v1 2/2] migration: Do not perform RAMBlock dirty sync during the first iteration Message-ID: References: <43700d36-b9f8-42da-ba72-b0ec6580032d@redhat.com> <3049bc19-2556-4fbf-9d34-578db523b63b@redhat.com> <382461ab-d620-4d2e-becd-720daadf3c55@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <382461ab-d620-4d2e-becd-720daadf3c55@redhat.com> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.119, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.738, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Nov 13, 2024 at 07:49:44PM +0100, David Hildenbrand wrote: > I think I had precisely that, and I recall you suggested to have it only > after the initial sync. Would work for me, but I'd still like to understand > why essentially none of the "discard" was effective -- all of guest RAM got > touched. Yes it'll be interesting to know.. One thing I'm wildly guessing is dirty_memory_extend(), so maybe after the ramblock is created nobody yet to clear the "1"s there for each of the client, including DIRTY_MEMORY_MIGRATION. Then it'll be synced to ramblock bmap only in the initial sync, once for each qemu lifecycle. -- Peter Xu