Sorry for the late reply due to CNY.
Auto-converge ensure that live migration can be completed smoothly when there
are too many dirty pages.
COLO may encounter the same situation when rebuild a new secondary VM.
So, I think it is necessary to enable COLO and auto-converge at the same time.
Thanks,
Lei.
-----Original Message-----
From: Lukas Straub <lukasstra...@web.de>
Sent: Sunday, February 14, 2021 6:52 PM
To: Rao, Lei <lei....@intel.com>
Cc: Zhang, Chen <chen.zh...@intel.com>; lizhij...@cn.fujitsu.com;
jasow...@redhat.com; zhang.zhanghaili...@huawei.com; quint...@redhat.com;
dgilb...@redhat.com; qemu-devel@nongnu.org
Subject: Re: [PATCH 07/10] Disable auto-coverge before entering COLO mode.
On Wed, 13 Jan 2021 10:46:32 +0800
leirao <lei....@intel.com> wrote:
> From: "Rao, Lei" <lei....@intel.com>
>
> If we don't disable the feature of auto-converge for live migration
> before entering COLO mode, it will continue to run with COLO running,
> and eventually the system will hang due to the CPU throttle reaching
> DEFAULT_MIGRATE_MAX_CPU_THROTTLE.
>
> Signed-off-by: Lei Rao <lei....@intel.com>
> ---
> migration/migration.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/migration/migration.c b/migration/migration.c index
> 31417ce..6ab37e5 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1673,6 +1673,20 @@ void migrate_set_block_enabled(bool value, Error
> **errp)
> qapi_free_MigrationCapabilityStatusList(cap);
> }
>
> +static void colo_auto_converge_enabled(bool value, Error **errp) {
> + MigrationCapabilityStatusList *cap = NULL;
> +
> + if (migrate_colo_enabled() && migrate_auto_converge()) {
> + QAPI_LIST_PREPEND(cap,
> + migrate_cap_add(MIGRATION_CAPABILITY_AUTO_CONVERGE,
> + value));
> + qmp_migrate_set_capabilities(cap, errp);
> + qapi_free_MigrationCapabilityStatusList(cap);
> + }
> + cpu_throttle_stop();
> +}
> +
I think it's better to error out in migration_prepare or migrate_caps_check if
both colo and auto-converge is enabled.
> static void migrate_set_block_incremental(MigrationState *s, bool
> value) {
> s->parameters.block_incremental = value; @@ -3401,7 +3415,7 @@
> static MigIterateState migration_iteration_run(MigrationState *s)
> static void migration_iteration_finish(MigrationState *s) {
> /* If we enabled cpu throttling for auto-converge, turn it off. */
> - cpu_throttle_stop();
> + colo_auto_converge_enabled(false, &error_abort);
>
> qemu_mutex_lock_iothread();
> switch (s->state) {
--
