From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8B58DD2F7F2 for ; Thu, 17 Oct 2024 06:43:46 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t1KEF-0001iG-QC; Thu, 17 Oct 2024 02:43:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t1KED-0001hh-ST for qemu-devel@nongnu.org; Thu, 17 Oct 2024 02:43:21 -0400 Received: from mail-pg1-x536.google.com ([2607:f8b0:4864:20::536]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1t1KEC-0005IQ-2d for qemu-devel@nongnu.org; Thu, 17 Oct 2024 02:43:21 -0400 Received: by mail-pg1-x536.google.com with SMTP id 41be03b00d2f7-7ea7e250c54so417096a12.0 for ; Wed, 16 Oct 2024 23:43:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=smartx-com.20230601.gappssmtp.com; s=20230601; t=1729147398; x=1729752198; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=gkuUteniMACK6TVPruWS74ndE9dexfSbMnrEVOVSYNY=; b=26GoC+EOMnV3KCSGqLEOLfSJEJ5jm0FjVmVX0i2ONh1nQ+l2f7mP1Gv3f3BmgVwzYM +nYx0IiR9s5t3RTLlU62zC9vrmo1VUtGmyL6PiDKznnRqYufu1hQm/QbckjfXGTCzEfB t1CtC3d3FlYRJ5Lmg8ydIrddu/nWx/HnTxwh6Lw1tIonaV/827BO31wc2C188GB/T9j/ g68KwBsKd7/P6f7VY4ehDdw9fOsOTJcv8P0pd/Qh/5wv6j9Sk/3IVk/IRUGq1C0fAVGk Grqx34lJnuRGNpDLiT8hq5jfgE9GnQjsn5Z7ZMT2LhVtX/WZh33ppkEQsptGNEhm8iMT xEYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729147398; x=1729752198; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gkuUteniMACK6TVPruWS74ndE9dexfSbMnrEVOVSYNY=; b=XE3VPMT5JgS/4uq8U/DhJVwFZjJ7WoNVVwWdnB8FvApakxs4qKAJ4xuLwqwrw7meIM EiAmeKTqSg6aBLu3oKrD3jhAATIErwe2tAZH+ECLelQLyvU+VFRdFA6i1EXNmLya+TbN nJ30uoTQ5eyEyopSnMCOBrFnfIsFuPu6mMx9WipiLnc0izv5de3XLIMW7b8QQkpHJh0Q GfwmGU9pjUGWUfPWJUJa6py1RwX+ioCBw5SQIBcet45pIXtDdS9dF/EO7fW2ksjmKMjh 9up9GHaUj3N0mtgbnxQ/SKn52zVTMPUx3oyku6x1+r/gW+RF8YTaBqmPtDtxN6xp6osM xNcg== X-Gm-Message-State: AOJu0YyT2xdEe6sxoeir4fbU5jE7jCDg97NIK3VLgkOXyM9uaIa4KDHM r5HMA/oAwuH0Y/2NkU7iv3Z3JrxRx8r0Jao0HQBqHGHF1DfZE/uF/e01mW10YVdTAhoEjSf8Gnt oiFUQMQ== X-Google-Smtp-Source: AGHT+IGpjBhb0YHl1JDz/HyUUYop39j+CjmYDawSdpfuLNuqiZBUCjMSwamDkA0u51mn6rCTnCNtmw== X-Received: by 2002:a05:6a20:438d:b0:1d6:2378:cffd with SMTP id adf61e73a8af0-1d8c93f5dbemr27552546637.0.1729147397880; Wed, 16 Oct 2024 23:43:17 -0700 (PDT) Received: from Hyman-Dev-Euler.zelin.local ([85.208.104.155]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e3e08eba12sm1044372a91.29.2024.10.16.23.43.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Oct 2024 23:43:17 -0700 (PDT) From: yong.huang@smartx.com To: qemu-devel@nongnu.org Cc: Peter Xu , Fabiano Rosas , Richard Henderson , Paolo Bonzini , yong.huang@smartx.com Subject: [PATCH v4 5/6] migration: Support periodic RAMBlock dirty bitmap sync Date: Thu, 17 Oct 2024 14:42:54 +0800 Message-Id: X-Mailer: git-send-email 2.27.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::536; envelope-from=yong.huang@smartx.com; helo=mail-pg1-x536.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Hyman Huang When VM is configured with huge memory, the current throttle logic doesn't look like to scale, because migration_trigger_throttle() is only called for each iteration, so it won't be invoked for a long time if one iteration can take a long time. The periodic dirty sync aims to fix the above issue by synchronizing the ramblock from remote dirty bitmap and, when necessary, triggering the CPU throttle multiple times during a long iteration. This is a trade-off between synchronization overhead and CPU throttle impact. Signed-off-by: Hyman Huang --- migration/cpu-throttle.c | 65 +++++++++++++++++++++++++++++++++++++++- migration/cpu-throttle.h | 14 +++++++++ migration/migration.c | 14 +++++++-- migration/migration.h | 1 + migration/ram.c | 2 +- migration/trace-events | 1 + 6 files changed, 93 insertions(+), 4 deletions(-) diff --git a/migration/cpu-throttle.c b/migration/cpu-throttle.c index fa47ee2e21..342681cdd4 100644 --- a/migration/cpu-throttle.c +++ b/migration/cpu-throttle.c @@ -28,16 +28,22 @@ #include "qemu/main-loop.h" #include "sysemu/cpus.h" #include "cpu-throttle.h" +#include "migration.h" +#include "migration-stats.h" #include "trace.h" /* vcpu throttling controls */ -static QEMUTimer *throttle_timer; +static QEMUTimer *throttle_timer, *throttle_dirty_sync_timer; static unsigned int throttle_percentage; +static bool throttle_dirty_sync_timer_active; #define CPU_THROTTLE_PCT_MIN 1 #define CPU_THROTTLE_PCT_MAX 99 #define CPU_THROTTLE_TIMESLICE_NS 10000000 +/* Making sure RAMBlock dirty bitmap is synchronized every five seconds */ +#define CPU_THROTTLE_DIRTY_SYNC_TIMESLICE_MS 5000 + static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque) { double pct; @@ -112,6 +118,7 @@ void cpu_throttle_set(int new_throttle_pct) void cpu_throttle_stop(void) { qatomic_set(&throttle_percentage, 0); + cpu_throttle_dirty_sync_timer(false); } bool cpu_throttle_active(void) @@ -124,8 +131,64 @@ int cpu_throttle_get_percentage(void) return qatomic_read(&throttle_percentage); } +void cpu_throttle_dirty_sync_timer_tick(void *opaque) +{ + static uint64_t prev_sync_cnt; + uint64_t sync_cnt = stat64_get(&mig_stats.dirty_sync_count); + + /* + * The first iteration copies all memory anyhow and has no + * effect on guest performance, therefore omit it to avoid + * paying extra for the sync penalty. + */ + if (sync_cnt <= 1) { + goto end; + } + + if (sync_cnt == prev_sync_cnt) { + trace_cpu_throttle_dirty_sync(); + WITH_RCU_READ_LOCK_GUARD() { + migration_bitmap_sync_precopy(false); + } + } + +end: + prev_sync_cnt = stat64_get(&mig_stats.dirty_sync_count); + + timer_mod(throttle_dirty_sync_timer, + qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_DIRTY_SYNC_TIMESLICE_MS); +} + +static bool cpu_throttle_dirty_sync_active(void) +{ + return qatomic_read(&throttle_dirty_sync_timer_active); +} + +void cpu_throttle_dirty_sync_timer(bool enable) +{ + assert(throttle_dirty_sync_timer); + + if (enable) { + if (!cpu_throttle_dirty_sync_active()) { + timer_mod(throttle_dirty_sync_timer, + qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_DIRTY_SYNC_TIMESLICE_MS); + qatomic_set(&throttle_dirty_sync_timer_active, 1); + } + } else { + if (cpu_throttle_dirty_sync_active()) { + timer_del(throttle_dirty_sync_timer); + qatomic_set(&throttle_dirty_sync_timer_active, 0); + } + } +} + void cpu_throttle_init(void) { throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT, cpu_throttle_timer_tick, NULL); + throttle_dirty_sync_timer = + timer_new_ms(QEMU_CLOCK_VIRTUAL_RT, + cpu_throttle_dirty_sync_timer_tick, NULL); } diff --git a/migration/cpu-throttle.h b/migration/cpu-throttle.h index d65bdef6d0..420702b8d3 100644 --- a/migration/cpu-throttle.h +++ b/migration/cpu-throttle.h @@ -65,4 +65,18 @@ bool cpu_throttle_active(void); */ int cpu_throttle_get_percentage(void); +/** + * cpu_throttle_dirty_sync_timer_tick: + * + * Dirty sync timer hook. + */ +void cpu_throttle_dirty_sync_timer_tick(void *opaque); + +/** + * cpu_throttle_dirty_sync_timer: + * + * Start or stop the dirty sync timer. + */ +void cpu_throttle_dirty_sync_timer(bool enable); + #endif /* SYSEMU_CPU_THROTTLE_H */ diff --git a/migration/migration.c b/migration/migration.c index 2e10ca77af..f673e30069 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3291,12 +3291,17 @@ 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. */ + bql_lock(); + + /* + * If we enabled cpu throttling for auto-converge, turn it off. + * Stopping CPU throttle should be serialized by BQL to avoid + * racing for the throttle_dirty_sync_timer. + */ if (migrate_auto_converge()) { cpu_throttle_stop(); } - bql_lock(); switch (s->state) { case MIGRATION_STATUS_COMPLETED: runstate_set(RUN_STATE_POSTMIGRATE); @@ -3513,6 +3518,11 @@ static void *migration_thread(void *opaque) qemu_savevm_send_colo_enable(s->to_dst_file); } + if (migrate_auto_converge()) { + /* Start RAMBlock dirty bitmap sync timer */ + cpu_throttle_dirty_sync_timer(true); + } + bql_lock(); ret = qemu_savevm_state_setup(s->to_dst_file, &local_err); bql_unlock(); diff --git a/migration/migration.h b/migration/migration.h index 38aa1402d5..fbd0d19092 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -537,4 +537,5 @@ int migration_rp_wait(MigrationState *s); */ void migration_rp_kick(MigrationState *s); +void migration_bitmap_sync_precopy(bool last_stage); #endif diff --git a/migration/ram.c b/migration/ram.c index 9b5b350405..d284f63854 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1088,7 +1088,7 @@ static void migration_bitmap_sync(RAMState *rs, bool last_stage) } } -static void migration_bitmap_sync_precopy(bool last_stage) +void migration_bitmap_sync_precopy(bool last_stage) { Error *local_err = NULL; assert(ram_state); diff --git a/migration/trace-events b/migration/trace-events index 9a19599804..0638183056 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -381,3 +381,4 @@ migration_pagecache_insert(void) "Error allocating page" # cpu-throttle.c cpu_throttle_set(int new_throttle_pct) "set guest CPU throttled by %d%%" +cpu_throttle_dirty_sync(void) "" -- 2.27.0