On Fri, Sep 02, 2022 at 01:22:32AM +0800, huang...@chinatelecom.cn wrote:
> From: Hyman Huang(黄勇) <huang...@chinatelecom.cn>
>
> Implement dirty-limit convergence algo for live migration,
> which is kind of like auto-converge algo but using dirty-limit
> instead of cpu throttle to make migration convergent.
>
> Signed-off-by: Hyman Huang(黄勇) <huang...@chinatelecom.cn>
> ---
> migration/migration.c | 1 +
> migration/ram.c | 53
> +++++++++++++++++++++++++++++++++++++-------------
> migration/trace-events | 1 +
> 3 files changed, 42 insertions(+), 13 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index d117bb4..64696de 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -239,6 +239,7 @@ void migration_cancel(const Error *error)
> if (error) {
> migrate_set_error(current_migration, error);
> }
> + qmp_cancel_vcpu_dirty_limit(false, -1, NULL);
> migrate_fd_cancel(current_migration);
> }
>
> diff --git a/migration/ram.c b/migration/ram.c
> index dc1de9d..cc19c5e 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -45,6 +45,7 @@
> #include "qapi/error.h"
> #include "qapi/qapi-types-migration.h"
> #include "qapi/qapi-events-migration.h"
> +#include "qapi/qapi-commands-migration.h"
> #include "qapi/qmp/qerror.h"
> #include "trace.h"
> #include "exec/ram_addr.h"
> @@ -57,6 +58,8 @@
> #include "qemu/iov.h"
> #include "multifd.h"
> #include "sysemu/runstate.h"
> +#include "sysemu/dirtylimit.h"
> +#include "sysemu/kvm.h"
>
> #include "hw/boards.h" /* for machine_dump_guest_core() */
>
> @@ -1139,6 +1142,21 @@ static void migration_update_rates(RAMState *rs,
> int64_t end_time)
> }
> }
>
> +/*
> + * Enable dirty-limit to throttle down the guest
> + */
> +static void migration_dirty_limit_guest(void)
> +{
> + if (!dirtylimit_in_service()) {
> + MigrationState *s = migrate_get_current();
> + int64_t quota_dirtyrate = s->parameters.x_vcpu_dirty_limit;
> +
> + /* Set quota dirtyrate if dirty limit not in service */
> + qmp_set_vcpu_dirty_limit(false, -1, quota_dirtyrate, NULL);
> + trace_migration_dirty_limit_guest(quota_dirtyrate);
> + }
> +}
> +
> static void migration_trigger_throttle(RAMState *rs)
> {
> MigrationState *s = migrate_get_current();
> @@ -1148,22 +1166,31 @@ static void migration_trigger_throttle(RAMState *rs)
> uint64_t bytes_dirty_period = rs->num_dirty_pages_period *
> TARGET_PAGE_SIZE;
> uint64_t bytes_dirty_threshold = bytes_xfer_period * threshold / 100;
>
> - /* During block migration the auto-converge logic incorrectly detects
> - * that ram migration makes no progress. Avoid this by disabling the
> - * throttling logic during the bulk phase of block migration. */
> - if (migrate_auto_converge() && !blk_mig_bulk_active()) {
> - /* The following detection logic can be refined later. For now:
> - Check to see if the ratio between dirtied bytes and the approx.
> - amount of bytes that just got transferred since the last time
> - we were in this routine reaches the threshold. If that happens
> - twice, start or increase throttling. */
> -
> - if ((bytes_dirty_period > bytes_dirty_threshold) &&
> - (++rs->dirty_rate_high_cnt >= 2)) {
> + /*
> + * The following detection logic can be refined later. For now:
> + * Check to see if the ratio between dirtied bytes and the approx.
> + * amount of bytes that just got transferred since the last time
> + * we were in this routine reaches the threshold. If that happens
> + * twice, start or increase throttling.
> + */
> +
> + if ((bytes_dirty_period > bytes_dirty_threshold) &&
> + (++rs->dirty_rate_high_cnt >= 2)) {
> + rs->dirty_rate_high_cnt = 0;
> + /*
> + * During block migration the auto-converge logic incorrectly detects
> + * that ram migration makes no progress. Avoid this by disabling the
> + * throttling logic during the bulk phase of block migration
> + */
> +
> + if (migrate_auto_converge() && !blk_mig_bulk_active()) {
> trace_migration_throttle();
> - rs->dirty_rate_high_cnt = 0;
> mig_throttle_guest_down(bytes_dirty_period,
> bytes_dirty_threshold);
> + } else if (migrate_dirty_limit() &&
> + kvm_dirty_ring_enabled() &&
> + migration_is_active(s)) {
> + migration_dirty_limit_guest();
We'll call this multiple time, but only the 1st call will make sense, right?
Can we call it once somewhere? E.g. at the start of migration?
Thanks,
--
Peter Xu
