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 F30DACD4F52 for ; Mon, 18 May 2026 11:02:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wOvj0-0006ad-FK; Mon, 18 May 2026 07:01:30 -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-0006Za-1D for qemu-devel@nongnu.org; Mon, 18 May 2026 07:01:28 -0400 Received: from out30-111.freemail.mail.aliyun.com ([115.124.30.111]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wOviu-0005iO-5E 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=1779102078; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=/Hf9bNk5euKjuZd4SN8a7/rLYdpLWK+prrB/RupffPk=; b=uFndEFNu9MfosrdLoTNwjdDueA4IGJ2L2kWcANcZb6WMK730m0nIqqL3AThgc2dTAIGPLy3rvOA950VIB3m2voiKNPwY0bU/6swyhKDK5P6Xd23aMMhM9tQTcxDzllzd+KzKd6E3+zAiflQKSg+YExdHxBV75np61iDL5bRqbjI= X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R201e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=maildocker-contentspam033037033178; MF=guobin@linux.alibaba.com; NM=1; PH=DS; RN=3; SR=0; TI=SMTPD_---0X382z.a_1779102076; Received: from localhost(mailfrom:guobin@linux.alibaba.com fp:SMTPD_---0X382z.a_1779102076 cluster:ay36) by smtp.aliyun-inc.com; Mon, 18 May 2026 19:01:16 +0800 From: Bin Guo To: qemu-devel@nongnu.org Cc: peterx@redhat.com, farosas@suse.de Subject: [PATCH 4/8] migration/savevm: use stack-allocated bitmap in configuration_validate_capabilities Date: Mon, 18 May 2026 19:01:08 +0800 Message-ID: <20260518110112.21395-5-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=115.124.30.111; envelope-from=guobin@linux.alibaba.com; helo=out30-111.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 configuration_validate_capabilities() allocates a bitmap on the heap to track source capabilities via bitmap_new()/g_free(). Since MIGRATION_CAPABILITY__MAX is a small compile-time constant (< 64), a heap allocation for a bitmap this small is wasteful: it adds malloc/free overhead and a potential cache miss for a transient 8-byte allocation. Replace with DECLARE_BITMAP() on the stack and bitmap_zero() to initialize. This eliminates the heap round-trip entirely. Signed-off-by: Bin Guo --- migration/savevm.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/migration/savevm.c b/migration/savevm.c index d1dd696c17..23adaf9dd9 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -347,10 +347,10 @@ static bool configuration_validate_capabilities(SaveState *state) { bool ret = true; MigrationState *s = migrate_get_current(); - unsigned long *source_caps_bm; + DECLARE_BITMAP(source_caps_bm, MIGRATION_CAPABILITY__MAX); int i; - source_caps_bm = bitmap_new(MIGRATION_CAPABILITY__MAX); + bitmap_zero(source_caps_bm, MIGRATION_CAPABILITY__MAX); for (i = 0; i < state->caps_count; i++) { MigrationCapability capability = state->capabilities[i]; set_bit(capability, source_caps_bm); @@ -373,7 +373,6 @@ static bool configuration_validate_capabilities(SaveState *state) } } - g_free(source_caps_bm); return ret; } -- 2.50.1 (Apple Git-155)