From patchwork Mon Jun 1 18:39:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 281519 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49E2BC433E1 for ; Mon, 1 Jun 2020 18:46:38 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 15A45206E2 for ; Mon, 1 Jun 2020 18:46:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Sdcnpge4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 15A45206E2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48142 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jfpSH-0000cw-9m for qemu-devel@archiver.kernel.org; Mon, 01 Jun 2020 14:46:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42154) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jfpMW-0007dm-1b for qemu-devel@nongnu.org; Mon, 01 Jun 2020 14:40:40 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:49995 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jfpMU-0000SO-OV for qemu-devel@nongnu.org; Mon, 01 Jun 2020 14:40:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591036838; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=i9cOhqO1L7Jwh3K0v3hi//aoSYGetnouMO5vLcBIC+k=; b=Sdcnpge4lYZ7bQoQBId3CvhQNHQm/nR25tiwpLltxp6pVfbGbLfyZ0iZzsJl0GLD4sj6xC QvFqrbapIHGFk4LpXxo9b3iGY068Gj1sYnqzFkFPc/19lTqWsMx6Tb4lHegthovC8ddRGC XRTYIO4qVCXBsd7C+pj4aAlOwWY2rY4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-41-QsTvdVf_PG6vkxq60n3NmQ-1; Mon, 01 Jun 2020 14:40:26 -0400 X-MC-Unique: QsTvdVf_PG6vkxq60n3NmQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A29908018A5; Mon, 1 Jun 2020 18:40:25 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-113-144.ams2.redhat.com [10.36.113.144]) by smtp.corp.redhat.com (Postfix) with ESMTP id 257F910016DA; Mon, 1 Jun 2020 18:40:23 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org Subject: [PULL 07/12] migration/colo.c: Use event instead of semaphore Date: Mon, 1 Jun 2020 19:39:59 +0100 Message-Id: <20200601184004.272784-8-dgilbert@redhat.com> In-Reply-To: <20200601184004.272784-1-dgilbert@redhat.com> References: <20200601184004.272784-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=207.211.31.120; envelope-from=dgilbert@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/01 11:55:48 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, T_HK_NAME_DR=0.01, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mszeredi@redhat.com, lukasstraub2@web.de, quintela@redhat.com, pannengyuan@huawei.com, f4bug@amsat.org, stefanha@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Lukas Straub If multiple packets miscompare in a short timeframe, the semaphore value will be increased multiple times. This causes multiple checkpoints even if one would be sufficient. Fix this by using a event instead of a semaphore for triggering checkpoints. Now, checkpoint requests will be ignored until the checkpoint event is sent to colo-compare (which releases the miscompared packets). Benchmark results (iperf3): Client-to-server tcp: without patch: ~66 Mbit/s with patch: ~61 Mbit/s Server-to-client tcp: without patch: ~702 Kbit/s with patch: ~16 Mbit/s Signed-off-by: Lukas Straub Message-Id: Reviewed-by: zhanghailiang Signed-off-by: Dr. David Alan Gilbert --- migration/colo.c | 9 +++++---- migration/migration.h | 4 ++-- 2 files changed, 7 insertions(+), 6 deletions(-) diff --git a/migration/colo.c b/migration/colo.c index d015d4f84e..fe0d6e93e5 100644 --- a/migration/colo.c +++ b/migration/colo.c @@ -436,6 +436,7 @@ static int colo_do_checkpoint_transaction(MigrationState *s, goto out; } + qemu_event_reset(&s->colo_checkpoint_event); colo_notify_compares_event(NULL, COLO_EVENT_CHECKPOINT, &local_err); if (local_err) { goto out; @@ -589,7 +590,7 @@ static void colo_process_checkpoint(MigrationState *s) goto out; } - qemu_sem_wait(&s->colo_checkpoint_sem); + qemu_event_wait(&s->colo_checkpoint_event); if (s->state != MIGRATION_STATUS_COLO) { goto out; @@ -637,7 +638,7 @@ out: colo_compare_unregister_notifier(&packets_compare_notifier); timer_del(s->colo_delay_timer); timer_free(s->colo_delay_timer); - qemu_sem_destroy(&s->colo_checkpoint_sem); + qemu_event_destroy(&s->colo_checkpoint_event); /* * Must be called after failover BH is completed, @@ -654,7 +655,7 @@ void colo_checkpoint_notify(void *opaque) MigrationState *s = opaque; int64_t next_notify_time; - qemu_sem_post(&s->colo_checkpoint_sem); + qemu_event_set(&s->colo_checkpoint_event); s->colo_checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST); next_notify_time = s->colo_checkpoint_time + s->parameters.x_checkpoint_delay; @@ -664,7 +665,7 @@ void colo_checkpoint_notify(void *opaque) void migrate_start_colo_process(MigrationState *s) { qemu_mutex_unlock_iothread(); - qemu_sem_init(&s->colo_checkpoint_sem, 0); + qemu_event_init(&s->colo_checkpoint_event, false); s->colo_delay_timer = timer_new_ms(QEMU_CLOCK_HOST, colo_checkpoint_notify, s); diff --git a/migration/migration.h b/migration/migration.h index 507284e563..f617960522 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -215,8 +215,8 @@ struct MigrationState /* The semaphore is used to notify COLO thread that failover is finished */ QemuSemaphore colo_exit_sem; - /* The semaphore is used to notify COLO thread to do checkpoint */ - QemuSemaphore colo_checkpoint_sem; + /* The event is used to notify COLO thread to do checkpoint */ + QemuEvent colo_checkpoint_event; int64_t colo_checkpoint_time; QEMUTimer *colo_delay_timer;