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Re: [Qemu-devel] [PATCH v4 4/4] migration: use the free page hint featur
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v4 4/4] migration: use the free page hint feature from balloon |
Date: |
Wed, 14 Mar 2018 19:49:55 +0000 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
* Wei Wang (address@hidden) 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;
An easier thing is just to clear the ram_bulk_stage flag (and if you're
doing it in the middle of the migration you need to reset some of the
pointers; see postcopy_start for an example).
> } 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();
Does balloon_free_page_stop cause it to immediately stop, or does it
just ask nicely? Could a slow guest keep pumping advice to us even
when it was stopped?
> + }
> +
> 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();
> + }
> }
>
> /**
> @@ -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();
That's probably the wrong test for postcopy; I think it'll always
be false there. Using migrate_postcopy_ram() tells you whether
postcopy-ram is enabled; although not necessarily in use at that
point.
Dave
> }
>
> #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
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH v4 2/4] migration: API to clear bits of guest free pages from the dirty bitmap, (continued)
[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,
Dr. David Alan Gilbert <=
[Qemu-devel] [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Wei Wang, 2018/03/07
- Re: [Qemu-devel] [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Michael S. Tsirkin, 2018/03/13
- Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Wei Wang, 2018/03/13
- Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Michael S. Tsirkin, 2018/03/13
- Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Wei Wang, 2018/03/14
- Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Michael S. Tsirkin, 2018/03/14
- Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Wei Wang, 2018/03/14
- Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Michael S. Tsirkin, 2018/03/14
- Re: [Qemu-devel] [virtio-dev] Re: [PATCH v4 3/4] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT, Wei Wang, 2018/03/15