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Tue, 12 Jul 2022 17:33:49 -0700 (PDT) MIME-Version: 1.0 References: <20220711211112.18951-1-leobras@redhat.com> <20220711211112.18951-4-leobras@redhat.com> In-Reply-To: From: Leonardo Bras Soares Passos Date: Tue, 12 Jul 2022 21:33:38 -0300 Message-ID: Subject: Re: [PATCH v4 3/3] migration/multifd: Report to user when zerocopy not working To: Peter Xu Cc: =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Juan Quintela , "Dr. David Alan Gilbert" , Eric Blake , Markus Armbruster , qemu-devel Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=lsoaresp@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Jul 12, 2022 at 7:42 PM Peter Xu wrote: > > On Mon, Jul 11, 2022 at 06:11:13PM -0300, Leonardo Bras wrote: > > Some errors, like the lack of Scatter-Gather support by the network > > interface(NETIF_F_SG) may cause sendmsg(...,MSG_ZEROCOPY) to fail on us= ing > > zero-copy, which causes it to fall back to the default copying mechanis= m. > > > > After each full dirty-bitmap scan there should be a zero-copy flush > > happening, which checks for errors each of the previous calls to > > sendmsg(...,MSG_ZEROCOPY). If all of them failed to use zero-copy, then > > increment dirty_sync_missed_zero_copy migration stat to let the user kn= ow > > about it. > > > > Signed-off-by: Leonardo Bras > > Reviewed-by: Daniel P. Berrang=C3=A9 > > Acked-by: Peter Xu Thanks Peter! > -- > Peter Xu >