From 2516a21205e67078cb735e9fd47ba50156c166b7 Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Mon, 11 Jul 2022 18:11:13 -0300 Subject: [PATCH 5/9] migration/multifd: Report to user when zerocopy not working MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Leonardo Brás RH-MergeRequest: 201: Zero-copy-send fixes + improvements RH-Commit: [5/8] 0b2e23b7f8ae72936e11369cd44ba474ef3b9e8c RH-Bugzilla: 2110203 RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Peter Xu RH-Acked-by: Miroslav Rezanina 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 Acked-by: Peter Xu Message-Id: <20220711211112.18951-4-leobras@redhat.com> Signed-off-by: Dr. David Alan Gilbert (cherry picked from commit d59c40cc483729f2e67c80e58df769ad19976fe9) Signed-off-by: Leonardo Bras --- migration/multifd.c | 2 ++ migration/ram.c | 5 +++++ migration/ram.h | 2 ++ 3 files changed, 9 insertions(+) diff --git a/migration/multifd.c b/migration/multifd.c index 90ab4c4346..7c16523e6b 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -631,6 +631,8 @@ 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 e7173da217..93cdb456ac 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -403,6 +403,11 @@ 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 */ diff --git a/migration/ram.h b/migration/ram.h index c515396a9a..69c3ccb26a 100644 --- a/migration/ram.h +++ b/migration/ram.h @@ -88,4 +88,6 @@ 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 -- 2.31.1