migration: disable auto-converge during bulk block migration
PATCH 1/1 migration: disable auto-converge during bulk block migration
auto-converge and block migration currently do not play well together. During block migration the auto-converge logic detects that ram migration makes no progress and thus throttles down the vm until it nearly stalls completely. Avoid this by disabling the throttling logic during the bulk phase of the block migration.
--- migration/block.c | 5 +++++ migration/block.h | 7 +++++++ migration/ram.c | 3 ++- 3 files changed, 14 insertions(+), 1 deletion(-)
migration/block.c +5 -0
@@ -161,6 +161,11 @@ int blk_mig_active(void)return !QSIMPLEQ_EMPTY (&block_mig_state.bmds_list); } +int blk_mig_bulk_active (void ) +{ +return blk_mig_active () && !block_mig_state.bulk_completed; +} +uint64_t blk_mig_bytes_transferred (void ) {BlkMigDevState *bmds;
migration/block.h +7 -0
@@ -16,6 +16,7 @@#ifdef CONFIG_LIVE_BLOCK_MIGRATION int blk_mig_active (void ); +int blk_mig_bulk_active (void );uint64_t blk_mig_bytes_transferred (void );uint64_t blk_mig_bytes_remaining (void );uint64_t blk_mig_bytes_total (void );
@@ -25,6 +26,12 @@ static inline int blk_mig_active(void) {return false; } + +static inline int blk_mig_bulk_active (void ) +{ +return false; +} +static inline uint64_t blk_mig_bytes_transferred (void ) {return 0 ;
migration/ram.c +2 -1
@@ -46,6 +46,7 @@#include "exec/ram_addr.h" #include "qemu/rcu_queue.h" #include "migration/colo.h" +#include "migration/block.h" /***********************************************************/ /* ram save/restore */
@@ -623,7 +624,7 @@ static void migration_bitmap_sync(RAMState *rs) / (end_time - rs->time_last_bitmap_sync); bytes_xfer_now = ram_counters.transferred; -if (migrate_auto_converge ()) { +if (migrate_auto_converge () && !blk_mig_bulk_active ()) {/* The following detection logic can be refined later. For now: Check to see if the dirtied bytes is 50% more than the approx. amount of bytes that just got transferred since the last time we
Signature · 1 line
1.9.1
Quoted 5 lines · Peter Lieven
auto-converge and block migration currently do not play well together. During block migration the auto-converge logic detects that ram migration makes no progress and thus throttles down the vm until it nearly stalls completely. Avoid this by disabling the throttling logic during the bulk phase of the block migration.
Please include the rationale in a comment here:
migration/ram.c static void migration_bitmap_sync(RAMState *rs) · line 627
Quoted 2 lines
migration/ram.c +1
-1-if (migrate_auto_converge ()) { +if (migrate_auto_converge () && !blk_mig_bulk_active ()) {
That way it's clear why auto-converge isn't enabled when block migration is active.
Quoting Peter Lieven (2017-09-21 07:32:32)
Quoted 8 lines
auto-converge and block migration currently do not play well together. During block migration the auto-converge logic detects that ram migration makes no progress and thus throttles down the vm until it nearly stalls completely. Avoid this by disabling the throttling logic during the bulk phase of the block migration.
Signed-off-by Peter Lieven <[email protected]>
FYI: this patch has been tagged for stable 2.10.1, but is not yet upstream. Patch freeze for 2.10.1 is September 27th.
Quoted 72 lines
--- migration/block.c | 5 +++++ migration/block.h | 7 +++++++ migration/ram.c | 3 ++- 3 files changed, 14 insertions(+), 1 deletion(-)migration/block.c +5
-0@@ -161,6 +161,11 @@ int blk_mig_active(void)return !QSIMPLEQ_EMPTY (&block_mig_state.bmds_list); } +int blk_mig_bulk_active (void ) +{ +return blk_mig_active () && !block_mig_state.bulk_completed; +} +uint64_t blk_mig_bytes_transferred (void ) {BlkMigDevState *bmds;migration/block.h +7
-0@@ -16,6 +16,7 @@#ifdef CONFIG_LIVE_BLOCK_MIGRATION int blk_mig_active (void ); +int blk_mig_bulk_active (void );uint64_t blk_mig_bytes_transferred (void );uint64_t blk_mig_bytes_remaining (void );uint64_t blk_mig_bytes_total (void );@@ -25,6 +26,12 @@ static inline int blk_mig_active(void) {return false; } + +static inline int blk_mig_bulk_active (void ) +{ +return false; +} +static inline uint64_t blk_mig_bytes_transferred (void ) {return 0 ;migration/ram.c +2
-1@@ -46,6 +46,7 @@#include "exec/ram_addr.h" #include "qemu/rcu_queue.h" #include "migration/colo.h" +#include "migration/block.h" /***********************************************************/ /* ram save/restore */ @@ -623,7 +624,7 @@ static void migration_bitmap_sync(RAMState *rs) / (end_time - rs->time_last_bitmap_sync); bytes_xfer_now = ram_counters.transferred; -if (migrate_auto_converge ()) { +if (migrate_auto_converge () && !blk_mig_bulk_active ()) {/* The following detection logic can be refined later. For now: Check to see if the dirtied bytes is 50% more than the approx. amount of bytes that just got transferred since the last time we Signature · 1 line
1.9.1
Am 25.09.2017 um 22:53 schrieb Michael Roth:
Quoted 11 lines
Quoting Peter Lieven (2017-09-21 07:32:32)
Quoted 8 lines
auto-converge and block migration currently do not play well together. During block migration the auto-converge logic detects that ram migration makes no progress and thus throttles down the vm until it nearly stalls completely. Avoid this by disabling the throttling logic during the bulk phase of the block migration.
Signed-off-by Peter Lieven <[email protected]>FYI: this patch has been tagged for stable 2.10.1, but is not yet upstream. Patch freeze for 2.10.1 is September 27th.
I just send a V2 of the patch adding a comment to the code why auto-converge is disabled during bulk block migration. Maybe someone can review it and pick it up.
Peter
Am 25.09.2017 um 22:53 schrieb Michael Roth:
Quoted 11 lines
Quoting Peter Lieven (2017-09-21 07:32:32)
Quoted 8 lines
auto-converge and block migration currently do not play well together. During block migration the auto-converge logic detects that ram migration makes no progress and thus throttles down the vm until it nearly stalls completely. Avoid this by disabling the throttling logic during the bulk phase of the block migration.
Signed-off-by Peter Lieven <[email protected]>FYI: this patch has been tagged for stable 2.10.1, but is not yet upstream. Patch freeze for 2.10.1 is September 27th.
Hi Michael,
the patch went upstream yesterday.
Peter