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[Qemu-devel] [PULL 24/33] migration: always initialise ram_counters for
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PULL 24/33] migration: always initialise ram_counters for a new migration |
Date: |
Thu, 15 Aug 2019 17:34:55 +0100 |
From: Ivan Ren <address@hidden>
This patch fix a multifd migration bug in migration speed calculation, this
problem can be reproduced as follows:
1. start a vm and give a heavy memory write stress to prevent the vm be
successfully migrated to destination
2. begin a migration with multifd
3. migrate for a long time [actually, this can be measured by transferred bytes]
4. migrate cancel
5. begin a new migration with multifd, the migration will directly run into
migration_completion phase
Reason as follows:
Migration update bandwidth and s->threshold_size in function
migration_update_counters after BUFFER_DELAY time:
current_bytes = migration_total_bytes(s);
transferred = current_bytes - s->iteration_initial_bytes;
time_spent = current_time - s->iteration_start_time;
bandwidth = (double)transferred / time_spent;
s->threshold_size = bandwidth * s->parameters.downtime_limit;
In multifd migration, migration_total_bytes function return
qemu_ftell(s->to_dst_file) + ram_counters.multifd_bytes.
s->iteration_initial_bytes will be initialized to 0 at every new migration,
but ram_counters is a global variable, and history migration data will be
accumulated. So if the ram_counters.multifd_bytes is big enough, it may lead
pending_size >= s->threshold_size become false in migration_iteration_run
after the first migration_update_counters.
Signed-off-by: Ivan Ren <address@hidden>
Reviewed-by: Juan Quintela <address@hidden>
Reviewed-by: Wei Yang <address@hidden>
Suggested-by: Wei Yang <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
migration/migration.c | 25 +++++++++++++++++++------
migration/savevm.c | 1 +
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 12b8e5dbe5..c49e9dc035 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1911,6 +1911,11 @@ static bool migrate_prepare(MigrationState *s, bool blk,
bool blk_inc,
}
migrate_init(s);
+ /*
+ * set ram_counters memory to zero for a
+ * new migration
+ */
+ memset(&ram_counters, 0, sizeof(ram_counters));
return true;
}
@@ -3034,6 +3039,17 @@ static void migration_calculate_complete(MigrationState
*s)
}
}
+static void update_iteration_initial_status(MigrationState *s)
+{
+ /*
+ * Update these three fields at the same time to avoid mismatch info lead
+ * wrong speed calculation.
+ */
+ s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+ s->iteration_initial_bytes = migration_total_bytes(s);
+ s->iteration_initial_pages = ram_get_total_transferred_pages();
+}
+
static void migration_update_counters(MigrationState *s,
int64_t current_time)
{
@@ -3069,9 +3085,7 @@ static void migration_update_counters(MigrationState *s,
qemu_file_reset_rate_limit(s->to_dst_file);
- s->iteration_start_time = current_time;
- s->iteration_initial_bytes = current_bytes;
- s->iteration_initial_pages = ram_get_total_transferred_pages();
+ update_iteration_initial_status(s);
trace_migrate_transferred(transferred, time_spent,
bandwidth, s->threshold_size);
@@ -3194,7 +3208,7 @@ static void *migration_thread(void *opaque)
rcu_register_thread();
object_ref(OBJECT(s));
- s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+ update_iteration_initial_status(s);
qemu_savevm_state_header(s->to_dst_file);
@@ -3259,8 +3273,7 @@ static void *migration_thread(void *opaque)
* the local variables. This is important to avoid
* breaking transferred_bytes and bandwidth calculation
*/
- s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
- s->iteration_initial_bytes = 0;
+ update_iteration_initial_status(s);
}
current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
diff --git a/migration/savevm.c b/migration/savevm.c
index 412768216c..1ac15301ad 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1456,6 +1456,7 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
}
migrate_init(ms);
+ memset(&ram_counters, 0, sizeof(ram_counters));
ms->to_dst_file = f;
qemu_mutex_unlock_iothread();
--
2.21.0
- [Qemu-devel] [PULL 14/33] migration: use migration_in_postcopy() to check POSTCOPY_ACTIVE, (continued)
- [Qemu-devel] [PULL 14/33] migration: use migration_in_postcopy() to check POSTCOPY_ACTIVE, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 15/33] migration: just pass RAMBlock is enough, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 17/33] migration: return -EINVAL directly when version_id mismatch, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 16/33] migration: equation is more proper than and to check LOADVM_QUIT, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 18/33] migration: extract ram_load_precopy, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 19/33] migration/postcopy: make PostcopyDiscardState a static variable, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 20/33] migration/postcopy: simplify calculation of run_start and fixup_start_addr, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 21/33] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 22/33] hmp: Remove migration capabilities from "info migrate", Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 23/33] migration: remove unused field bytes_xfer, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 24/33] migration: always initialise ram_counters for a new migration,
Dr. David Alan Gilbert (git) <=
- [Qemu-devel] [PULL 25/33] migration: add qemu_file_update_transfer interface, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 26/33] migration: add speed limit for multifd migration, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 27/33] migration: update ram_counters for multifd sync packet, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 28/33] migration: rename migration_bitmap_sync_range to ramblock_sync_dirty_bitmap, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 30/33] qemu-file: move qemu_{get, put}_counted_string() declarations, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 29/33] migration/postcopy: use mis->bh instead of allocating a QEMUBH, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 31/33] migration: Add traces for multifd terminate threads, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 32/33] migration: Make global sem_sync semaphore by channel, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 33/33] migration: add some multifd traces, Dr. David Alan Gilbert (git), 2019/08/15
- Re: [Qemu-devel] [PULL 00/33] migration queue, Peter Maydell, 2019/08/16