From c8750de11810ddca96026fc0edf87b64c1350f76 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Thu, 7 Jul 2022 14:55:11 -0400 Subject: migration: Add property x-postcopy-preempt-break-huge Add a property field that can conditionally disable the "break sending huge page" behavior in postcopy preemption. By default it's enabled. It should only be used for debugging purposes, and we should never remove the "x-" prefix. Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Manish Mishra Signed-off-by: Peter Xu Message-Id: <20220707185511.27366-1-peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- migration/migration.c | 2 ++ migration/migration.h | 7 +++++++ migration/ram.c | 7 +++++++ 3 files changed, 16 insertions(+) (limited to 'migration') diff --git a/migration/migration.c b/migration/migration.c index 427d4de185..864164ad96 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -4363,6 +4363,8 @@ static Property migration_properties[] = { DEFINE_PROP_SIZE("announce-step", MigrationState, parameters.announce_step, DEFAULT_MIGRATE_ANNOUNCE_STEP), + DEFINE_PROP_BOOL("x-postcopy-preempt-break-huge", MigrationState, + postcopy_preempt_break_huge, true), /* Migration capabilities */ DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE), diff --git a/migration/migration.h b/migration/migration.h index ae4ffd3454..cdad8aceaa 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -340,6 +340,13 @@ struct MigrationState { bool send_configuration; /* Whether we send section footer during migration */ bool send_section_footer; + /* + * Whether we allow break sending huge pages when postcopy preempt is + * enabled. When disabled, we won't interrupt precopy within sending a + * host huge page, which is the old behavior of vanilla postcopy. + * NOTE: this parameter is ignored if postcopy preempt is not enabled. + */ + bool postcopy_preempt_break_huge; /* Needed by postcopy-pause state */ QemuSemaphore postcopy_pause_sem; diff --git a/migration/ram.c b/migration/ram.c index 65b08c4edb..7cbe9c310d 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2266,11 +2266,18 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss) static bool postcopy_needs_preempt(RAMState *rs, PageSearchStatus *pss) { + MigrationState *ms = migrate_get_current(); + /* Not enabled eager preempt? Then never do that. */ if (!migrate_postcopy_preempt()) { return false; } + /* If the user explicitly disabled breaking of huge page, skip */ + if (!ms->postcopy_preempt_break_huge) { + return false; + } + /* If the ramblock we're sending is a small page? Never bother. */ if (qemu_ram_pagesize(pss->block) == TARGET_PAGE_SIZE) { return false; -- cgit v1.2.3-55-g7522