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Re: [Qemu-devel] [PATCH 5/7] migration: Fix the migrate auto converge pr
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 5/7] migration: Fix the migrate auto converge process |
Date: |
Fri, 28 Feb 2014 10:16:17 +0000 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
* Gonglei (Arei) (address@hidden) wrote:
> It is inaccuracy and complex that using the transfer speed of
> migration thread to determine whether the convergence migration.
> The dirty page may be compressed by XBZRLE or ZERO_PAGE.The counter
> of updating dirty bitmap will be increasing continuously if the
> migration can't convergence.
>
> Signed-off-by: ChenLiang <address@hidden>
> Signed-off-by: Gonglei <address@hidden>
> ---
> arch_init.c | 26 +++-----------------------
> 1 file changed, 3 insertions(+), 23 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index fc71331..2211e0b 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -107,7 +107,6 @@ int graphic_depth = 32;
>
> const uint32_t arch_type = QEMU_ARCH;
> static bool mig_throttle_on;
> -static int dirty_rate_high_cnt;
> static void check_guest_throttling(void);
>
> static uint64_t bitmap_sync_cnt;
> @@ -464,17 +463,11 @@ static void migration_bitmap_sync(void)
> uint64_t num_dirty_pages_init = migration_dirty_pages;
> MigrationState *s = migrate_get_current();
> static int64_t start_time;
> - static int64_t bytes_xfer_prev;
> static int64_t num_dirty_pages_period;
> int64_t end_time;
> - int64_t bytes_xfer_now;
>
> increase_bitmap_sync_cnt();
>
> - if (!bytes_xfer_prev) {
> - bytes_xfer_prev = ram_bytes_transferred();
> - }
> -
> if (!start_time) {
> start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> }
> @@ -493,21 +486,9 @@ static void migration_bitmap_sync(void)
> /* more than 1 second = 1000 millisecons */
> if (end_time > start_time + 1000) {
> if (migrate_auto_converge()) {
> - /* 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
> - were in this routine. If that happens >N times (for now N==4)
> - we turn on the throttle down logic */
> - bytes_xfer_now = ram_bytes_transferred();
> - if (s->dirty_pages_rate &&
> - (num_dirty_pages_period * TARGET_PAGE_SIZE >
> - (bytes_xfer_now - bytes_xfer_prev)/2) &&
> - (dirty_rate_high_cnt++ > 4)) {
> - trace_migration_throttle();
> - mig_throttle_on = true;
> - dirty_rate_high_cnt = 0;
> - }
> - bytes_xfer_prev = bytes_xfer_now;
> + if (get_bitmap_sync_cnt() > 15) {
> + mig_throttle_on = true;
> + }
That is a lot simpler, and I suspect as good - again I'd
move that magic '15' to a constant somewhere.
What have you tested this on - have you tested with really big RAM VMs?
What's it's behaviour like with rate-limiting?
Dave
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK