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 lists1p.gnu.org (lists1p.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 05FFACD4F3C for ; Mon, 18 May 2026 11:01:45 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wOvj3-0006dO-CE; Mon, 18 May 2026 07:01:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wOviy-0006Zc-2r for qemu-devel@nongnu.org; Mon, 18 May 2026 07:01:28 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wOviu-0005ia-QW for qemu-devel@nongnu.org; Mon, 18 May 2026 07:01:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1779102079; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=GazgXwplieYD1E3kZIynTm21GjivhQWz7Fa/Q3ZVKPM=; b=lm3hx3GQdoJ8ovvNAcwKAkxxJan5a5qNVdlJRzY0Gn7XRl7NEVuXc0+7A8+OuNaO8mZnYCFy4dfta3c8Z1vo2Lt+G4KjXWvicF4SizvbB3YAMM4Hlq0Uz4gRlhJ4mh3Qm/VSjFUKYdFtNa0asWgBrqgKLSAsP+LWNOZ7oPeD20w= X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R121e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=maildocker-contentspam033037009110; MF=guobin@linux.alibaba.com; NM=1; PH=DS; RN=3; SR=0; TI=SMTPD_---0X38-ooA_1779102078; Received: from localhost(mailfrom:guobin@linux.alibaba.com fp:SMTPD_---0X38-ooA_1779102078 cluster:ay36) by smtp.aliyun-inc.com; Mon, 18 May 2026 19:01:19 +0800 From: Bin Guo To: qemu-devel@nongnu.org Cc: peterx@redhat.com, farosas@suse.de Subject: [PATCH 8/8] migration/multifd: cache channel count in multifd_send_sync_main Date: Mon, 18 May 2026 19:01:12 +0800 Message-ID: <20260518110112.21395-9-guobin@linux.alibaba.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260518110112.21395-1-guobin@linux.alibaba.com> References: <20260518110112.21395-1-guobin@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=115.124.30.130; envelope-from=guobin@linux.alibaba.com; helo=out30-130.freemail.mail.aliyun.com X-Spam_score_int: -174 X-Spam_score: -17.5 X-Spam_bar: ----------------- X-Spam_report: (-17.5 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, ENV_AND_HDR_SPF_MATCH=-0.5, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, UNPARSEABLE_RELAY=0.001, USER_IN_DEF_DKIM_WL=-7.5, USER_IN_DEF_SPF_WL=-7.5 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: qemu development 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 multifd_send_sync_main() is called once per RAM synchronization round during live migration. It iterates over all multifd channels twice (signal loop + wait loop), calling migrate_multifd_channels() independently in each loop header. Cache migrate_multifd_channels() in a local thread_count variable at function entry, matching the pattern already used in multifd_send_setup() and multifd_recv_setup(). This eliminates 2 redundant config lookups per sync call. Signed-off-by: Bin Guo --- migration/multifd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/migration/multifd.c b/migration/multifd.c index cc2fa90204..bc8aacd660 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -611,13 +611,15 @@ static int multifd_zero_copy_flush(QIOChannel *c) int multifd_send_sync_main(MultiFDSyncReq req) { int i; + int thread_count; bool flush_zero_copy; assert(req != MULTIFD_SYNC_NONE); + thread_count = migrate_multifd_channels(); flush_zero_copy = migrate_zero_copy_send(); - for (i = 0; i < migrate_multifd_channels(); i++) { + for (i = 0; i < thread_count; i++) { MultiFDSendParams *p = &multifd_send_state->params[i]; if (multifd_send_should_exit()) { @@ -634,7 +636,7 @@ int multifd_send_sync_main(MultiFDSyncReq req) qatomic_set(&p->pending_sync, req); qemu_sem_post(&p->sem); } - for (i = 0; i < migrate_multifd_channels(); i++) { + for (i = 0; i < thread_count; i++) { MultiFDSendParams *p = &multifd_send_state->params[i]; if (multifd_send_should_exit()) { -- 2.50.1 (Apple Git-155)