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[188.85.120.92]) by smtp.gmail.com with ESMTPSA id n3-20020a7bc5c3000000b003f0b1b8cd9bsm23446369wmk.4.2023.05.10.09.54.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 May 2023 09:54:59 -0700 (PDT) From: Juan Quintela To: Andrei Gudkov Cc: , , , , Subject: Re: [PATCH v2 1/4] migration/calc-dirty-rate: replaced CRC32 with xxHash In-Reply-To: (Andrei Gudkov's message of "Thu, 27 Apr 2023 15:42:57 +0300") References: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) Date: Wed, 10 May 2023 18:54:58 +0200 Message-ID: <87bkis6s9p.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=170.10.133.124; envelope-from=quintela@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Reply-To: quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Andrei Gudkov wrote: > This significantly reduces overhead of dirty page > rate calculation in sampling mode. > Tested using 32GiB VM on E5-2690 CPU. > > With CRC32: > total_pages=8388608 sampled_pages=16384 millis=71 > > With xxHash: > total_pages=8388608 sampled_pages=16384 millis=14 > > Signed-off-by: Andrei Gudkov Reviewed-by: Juan Quintela This changes nothing outside of dirtyrate, and if the hash function is faster, we should be good. queued.