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Mon, 11 Jul 2022 14:11:42 -0700 (PDT) Received: from LeoBras.redhat.com ([2804:431:c7f0:d647:bb68:29a5:e512:2c8b]) by smtp.gmail.com with ESMTPSA id q7-20020a0568080a8700b00339eb701c6csm3140343oij.41.2022.07.11.14.11.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Jul 2022 14:11:42 -0700 (PDT) From: Leonardo Bras To: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Juan Quintela , "Dr. David Alan Gilbert" , Eric Blake , Markus Armbruster , Peter Xu Cc: Leonardo Bras , qemu-devel@nongnu.org Subject: [PATCH v4 3/3] migration/multifd: Report to user when zerocopy not working Date: Mon, 11 Jul 2022 18:11:13 -0300 Message-Id: <20220711211112.18951-4-leobras@redhat.com> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220711211112.18951-1-leobras@redhat.com> References: <20220711211112.18951-1-leobras@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=leobras@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" Some errors, like the lack of Scatter-Gather support by the network interface(NETIF_F_SG) may cause sendmsg(...,MSG_ZEROCOPY) to fail on using zero-copy, which causes it to fall back to the default copying mechanism. 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 know about it. Signed-off-by: Leonardo Bras Reviewed-by: Daniel P. Berrangé --- migration/ram.h | 2 ++ migration/multifd.c | 2 ++ migration/ram.c | 5 +++++ 3 files changed, 9 insertions(+) diff --git a/migration/ram.h b/migration/ram.h index ded0a3a086..d3c7eb96f5 100644 --- a/migration/ram.h +++ b/migration/ram.h @@ -87,4 +87,6 @@ void ram_write_tracking_prepare(void); int ram_write_tracking_start(void); void ram_write_tracking_stop(void); +void dirty_sync_missed_zero_copy(void); + #endif diff --git a/migration/multifd.c b/migration/multifd.c index 684c014c86..3909b34967 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -624,6 +624,8 @@ int multifd_send_sync_main(QEMUFile *f) if (ret < 0) { error_report_err(err); return -1; + } else if (ret == 1) { + dirty_sync_missed_zero_copy(); } } } diff --git a/migration/ram.c b/migration/ram.c index 01f9cc1d72..db948c4787 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -407,6 +407,11 @@ static void ram_transferred_add(uint64_t bytes) ram_counters.transferred += bytes; } +void dirty_sync_missed_zero_copy(void) +{ + ram_counters.dirty_sync_missed_zero_copy++; +} + /* used by the search for pages to send */ struct PageSearchStatus { /* Current block being searched */ -- 2.37.0