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[Qemu-devel] [PATCH v3 1/1] migration: calculate expected_downtime with
From: |
Balamuruhan S |
Subject: |
[Qemu-devel] [PATCH v3 1/1] migration: calculate expected_downtime with ram_bytes_remaining() |
Date: |
Wed, 25 Apr 2018 12:40:40 +0530 |
expected_downtime value is not accurate with dirty_pages_rate * page_size,
using ram_bytes_remaining would yeild it correct. It will initially be a
gross over-estimate, but for for non-converging migrations it should
approach a reasonable estimate later on.
currently bandwidth and expected_downtime value are calculated in
migration_update_counters() during each iteration from
migration_thread(), where as remaining ram is calculated in
qmp_query_migrate() when we actually call "info migrate". Due to this
there is some difference in expected_downtime value being calculated.
with this patch bandwidth, expected_downtime and remaining ram are
calculated in migration_update_counters(), retrieve the same value during
"info migrate". By this approach we get almost close enough value.
Reported-by: Michael Roth <address@hidden>
Signed-off-by: Balamuruhan S <address@hidden>
---
migration/migration.c | 11 ++++++++---
migration/migration.h | 1 +
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 52a5092add..5d721ee481 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -614,7 +614,7 @@ static void populate_ram_info(MigrationInfo *info,
MigrationState *s)
}
if (s->state != MIGRATION_STATUS_COMPLETED) {
- info->ram->remaining = ram_bytes_remaining();
+ info->ram->remaining = s->ram_bytes_remaining;
info->ram->dirty_pages_rate = ram_counters.dirty_pages_rate;
}
}
@@ -2227,6 +2227,7 @@ static void migration_update_counters(MigrationState *s,
transferred = qemu_ftell(s->to_dst_file) - s->iteration_initial_bytes;
time_spent = current_time - s->iteration_start_time;
bandwidth = (double)transferred / time_spent;
+ s->ram_bytes_remaining = ram_bytes_remaining();
s->threshold_size = bandwidth * s->parameters.downtime_limit;
s->mbps = (((double) transferred * 8.0) /
@@ -2237,8 +2238,12 @@ static void migration_update_counters(MigrationState *s,
* recalculate. 10000 is a small enough number for our purposes
*/
if (ram_counters.dirty_pages_rate && transferred > 10000) {
- s->expected_downtime = ram_counters.dirty_pages_rate *
- qemu_target_page_size() / bandwidth;
+ /*
+ * It will initially be a gross over-estimate, but for for
+ * non-converging migrations it should approach a reasonable estimate
+ * later on
+ */
+ s->expected_downtime = s->ram_bytes_remaining / bandwidth;
}
qemu_file_reset_rate_limit(s->to_dst_file);
diff --git a/migration/migration.h b/migration/migration.h
index 8d2f320c48..8584f8e22e 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -128,6 +128,7 @@ struct MigrationState
int64_t downtime_start;
int64_t downtime;
int64_t expected_downtime;
+ int64_t ram_bytes_remaining;
bool enabled_capabilities[MIGRATION_CAPABILITY__MAX];
int64_t setup_time;
/*
--
2.14.3