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Re: [Qemu-devel] [PATCH v4 4/4] migration: use the free page hint featur
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v4 4/4] migration: use the free page hint feature from balloon |
Date: |
Tue, 13 Mar 2018 18:35:36 +0200 |
On Wed, Mar 07, 2018 at 08:34:25PM +0800, Wei Wang wrote:
> Start the free page optimization after the migration bitmap is
> synchronized. This can't be used in the stop© phase since the guest
> is paused. Make sure the guest reporting has stopped before
> synchronizing the migration dirty bitmap. Currently, the optimization is
> added to precopy only.
>
> Signed-off-by: Wei Wang <address@hidden>
> CC: Dr. David Alan Gilbert <address@hidden>
> CC: Juan Quintela <address@hidden>
> CC: Michael S. Tsirkin <address@hidden>
> ---
> migration/ram.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index e172798..7b4c9b1 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -51,6 +51,8 @@
> #include "qemu/rcu_queue.h"
> #include "migration/colo.h"
> #include "migration/block.h"
> +#include "sysemu/balloon.h"
> +#include "sysemu/sysemu.h"
>
> /***********************************************************/
> /* ram save/restore */
> @@ -208,6 +210,8 @@ struct RAMState {
> uint32_t last_version;
> /* We are in the first round */
> bool ram_bulk_stage;
> + /* The free pages optimization feature is supported */
> + bool free_page_support;
> /* How many times we have dirty too many pages */
> int dirty_rate_high_cnt;
> /* these variables are used for bitmap sync */
> @@ -775,7 +779,7 @@ unsigned long migration_bitmap_find_dirty(RAMState *rs,
> RAMBlock *rb,
> unsigned long *bitmap = rb->bmap;
> unsigned long next;
>
> - if (rs->ram_bulk_stage && start > 0) {
> + if (rs->ram_bulk_stage && start > 0 && !rs->free_page_support) {
> next = start + 1;
> } else {
> next = find_next_bit(bitmap, size, start);
> @@ -833,6 +837,10 @@ static void migration_bitmap_sync(RAMState *rs)
> int64_t end_time;
> uint64_t bytes_xfer_now;
>
> + if (rs->free_page_support) {
> + balloon_free_page_stop();
> + }
> +
> ram_counters.dirty_sync_count++;
>
> if (!rs->time_last_bitmap_sync) {
> @@ -899,6 +907,10 @@ static void migration_bitmap_sync(RAMState *rs)
> if (migrate_use_events()) {
> qapi_event_send_migration_pass(ram_counters.dirty_sync_count, NULL);
> }
> +
> + if (rs->free_page_support && runstate_is_running()) {
> + balloon_free_page_start();
> + }
> }
I think some of these conditions should go into
balloon_free_page_start/stop.
Checking runstate is generally problematic unless you
also handle run state change notifiers as it can
be manipulated from QMP.
>
> /**
> @@ -1656,6 +1668,8 @@ static void ram_state_reset(RAMState *rs)
> rs->last_page = 0;
> rs->last_version = ram_list.version;
> rs->ram_bulk_stage = true;
> + rs->free_page_support = balloon_free_page_support() &
> + !migration_in_postcopy();
Probably &&?
> }
>
> #define MAX_WAIT 50 /* ms, half buffered_file limit */
> @@ -2330,6 +2344,9 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
>
> ret = qemu_file_get_error(f);
> if (ret < 0) {
> + if (rs->free_page_support) {
> + balloon_free_page_stop();
> + }
> return ret;
> }
>
> --
> 1.8.3.1
[Qemu-devel] [PATCH v4 1/4] bitmap: bitmap_count_one_with_offset, Wei Wang, 2018/03/07
[Qemu-devel] [PATCH v4 4/4] migration: use the free page hint feature from balloon, Wei Wang, 2018/03/07
- Re: [Qemu-devel] [PATCH v4 4/4] migration: use the free page hint feature from balloon,
Michael S. Tsirkin <=
Re: [Qemu-devel] [PATCH v4 4/4] migration: use the free page hint feature from balloon, Dr. David Alan Gilbert, 2018/03/14
[Qemu-devel] [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Wei Wang, 2018/03/07