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[PATCH v3 3/3] migration/multifd: Warn user when zerocopy not working
From: |
Leonardo Bras |
Subject: |
[PATCH v3 3/3] migration/multifd: Warn user when zerocopy not working |
Date: |
Mon, 4 Jul 2022 17:23:15 -0300 |
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 <leobras@redhat.com>
---
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 */
--
2.36.1
- Re: [PATCH v3 1/3] QIOChannelSocket: Fix zero-copy flush returning code 1 when nothing sent, (continued)
[PATCH v3 2/3] Add dirty-sync-missed-zero-copy migration stat, Leonardo Bras, 2022/07/04
[PATCH v3 3/3] migration/multifd: Warn user when zerocopy not working,
Leonardo Bras <=