From 92aa523f5f2a3850340f7d63c10098fd99a760d2 Mon Sep 17 00:00:00 2001 From: liujing Date: Fri, 6 Sep 2024 17:08:21 +0800 Subject: [PATCH] migration: improve migration_throttle tracepoint Right now this tracepoint is just saying that the guest has been throttled, but this is not that good for debugging purposes. We should also know how much the guest is throttled in order to understand consequences for the guest behaviour. The patch moves the tracepoint from migration_trigger_throttle() to mig_throttle_guest_down() where this information is really available. This is not a problem as mig_throttle_guest_down() is called in the only one place. Signed-off-by: Denis V. Lunev Signed-off-by: liujing CC: Peter Xu CC: Fabiano Rosas --- migration/ram.c | 9 ++++++--- migration/trace-events | 2 +- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 998ee96e63..bb829c9d38 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -956,9 +956,11 @@ static void mig_throttle_guest_down(uint64_t bytes_dirty_period, uint64_t throttle_now = cpu_throttle_get_percentage(); uint64_t cpu_now, cpu_ideal, throttle_inc; + int new_throttle_pct; + /* We have not started throttling yet. Let's start it. */ if (!cpu_throttle_active()) { - cpu_throttle_set(pct_initial); + new_throttle_pct = pct_initial; } else { /* Throttling already on, just increase the rate */ if (!pct_tailslow) { @@ -971,8 +973,10 @@ static void mig_throttle_guest_down(uint64_t bytes_dirty_period, bytes_dirty_period); throttle_inc = MIN(cpu_now - cpu_ideal, pct_increment); } - cpu_throttle_set(MIN(throttle_now + throttle_inc, pct_max)); + new_throttle_pct = MIN(throttle_now + throttle_inc, pct_max); } + trace_migration_throttle(new_throttle_pct); + cpu_throttle_set(new_throttle_pct); } void mig_throttle_counter_reset(void) @@ -1460,7 +1464,6 @@ static void migration_trigger_throttle(RAMState *rs) (++rs->dirty_rate_high_cnt >= 2)) { rs->dirty_rate_high_cnt = 0; if (migrate_auto_converge()) { - trace_migration_throttle(); mig_throttle_guest_down(bytes_dirty_period, bytes_dirty_threshold); } else if (migrate_dirty_limit()) { diff --git a/migration/trace-events b/migration/trace-events index 246710f488..7393d94596 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -91,7 +91,7 @@ get_queued_page_not_dirty(const char *block_name, uint64_t tmp_offset, unsigned migration_bitmap_sync_start(void) "" migration_bitmap_sync_end(uint64_t dirty_pages) "dirty_pages %" PRIu64 migration_bitmap_clear_dirty(char *str, uint64_t start, uint64_t size, unsigned long page) "rb %s start 0x%"PRIx64" size 0x%"PRIx64" page 0x%lx" -migration_throttle(void) "" +migration_throttle(int new_throttle_pct) "guest CPU throttled by %d%%" migration_dirty_limit_guest(int64_t dirtyrate) "guest dirty page rate limit %" PRIi64 " MB/s" ram_discard_range(const char *rbname, uint64_t start, size_t len) "%s: start: %" PRIx64 " %zx" ram_load_loop(const char *rbname, uint64_t addr, int flags, void *host) "%s: addr: 0x%" PRIx64 " flags: 0x%x host: %p" -- Gitee