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 12669C433EF for ; Fri, 11 Feb 2022 01:51:11 +0000 (UTC) Received: from localhost ([::1]:50896 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nIL5a-0001uX-4t for qemu-devel@archiver.kernel.org; Thu, 10 Feb 2022 20:51:10 -0500 Received: from eggs.gnu.org ([209.51.188.92]:38578) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nIKmy-00042x-NW for qemu-devel@nongnu.org; Thu, 10 Feb 2022 20:31:58 -0500 Received: from [2607:f8b0:4864:20::102f] (port=45928 helo=mail-pj1-x102f.google.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1nIKmv-0007Lm-SS for qemu-devel@nongnu.org; Thu, 10 Feb 2022 20:31:56 -0500 Received: by mail-pj1-x102f.google.com with SMTP id q11-20020a17090a304b00b001b94d25eaecso2841894pjl.4 for ; Thu, 10 Feb 2022 17:31:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=xC7suoa36jFUtiePZKS+9H0vArd6rlJO37NOOnD8sis=; b=xYU8pXjzTNLQLkVtwpVD0yClayBGR/HKi694bjz4Mg3X1cyp/J5ENO5niSnq0t4WKF 5teB9nlY4emK1xG1jzRNJpYtgNCtpxBkM/Rgn78rdZBwxsii22AaGDdE6E2u8bqQ+z93 uuR1USrGCziMJMMRQl5UaR5j/xg9ViOUGkzeJMYO0lDpOyNYI495EpFuBZpwRT+aedIF hxF3pz/MvK4uGVCyKkooTWPL0D2DtTzx/mbiwJwuTjO3YqSeJJpSxTGhR2MGjZBXMjfb OmXH9rFRnf+zMYj5mnhhXxSme4qPKFHJZneciJx8OgCgFu2jO38zUODM4I/AVPWPkq+A Oqvg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=xC7suoa36jFUtiePZKS+9H0vArd6rlJO37NOOnD8sis=; b=UMmzUFvJCxYe9EySVqbCeh3ZoSToA4HqOdfsyGFSePTOJVZoFm3+VGfoZg72TJerCU SJbV2LaKbsYqW2HyVXCzSlQzE51NgrabhQOXqGvcXNaVkUP2ArjqNII60+b2/SRxsBDz haXBdgD8WIGb/5qdG0S69Agoi08UI0FV87OwFNnvAQLsYTcsV8hf6U37FET+p+BS4Ujy bQ4QekCF5nbox8Fjm5T7IavbhqIL6QIliilvE+PzTbwYtY+vYTrdXiMfkATCviriadLG Jz8bbIUw2qCilTU2iYYnjOmd9RJoDM84fk7u3nrDv5rWkcInwR3gA9uw9mDNYDeKb8Gk hCHQ== X-Gm-Message-State: AOAM53202FwBAMtXOR1vVXasI+XCKUQuN/GDIyoeGi4y1sDq43hM3GFR qyz25uWdjBri9iS/edsMyGlvLJhWqu/z8jfr X-Google-Smtp-Source: ABdhPJz+k+1NFwITEbuV+A6RZsTpWTxTGzMBQEXO71SM7x6GdbGO9/k0hZHdWl+eOxfo7liLGEFL9A== X-Received: by 2002:a17:902:7595:: with SMTP id j21mr10007349pll.79.1644543112629; Thu, 10 Feb 2022 17:31:52 -0800 (PST) Received: from localhost.localdomain ([124.189.222.164]) by smtp.gmail.com with ESMTPSA id h5sm25738788pfi.111.2022.02.10.17.31.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Feb 2022 17:31:52 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PULL 07/34] softmmu/cpus: Check if the cpu work list is empty atomically Date: Fri, 11 Feb 2022 12:30:32 +1100 Message-Id: <20220211013059.17994-8-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220211013059.17994-1-richard.henderson@linaro.org> References: <20220211013059.17994-1-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::102f (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::102f; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102f.google.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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: , Cc: peter.maydell@linaro.org, Idan Horowitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Idan Horowitz Instead of taking the lock of the cpu work list in order to check if it's empty, we can just read the head pointer atomically. This decreases cpu_work_list_empty's share from 5% to 1.3% in a profile of icount-enabled aarch64-softmmu. Signed-off-by: Idan Horowitz Message-Id: <20220114004358.299534-1-idan.horowitz@gmail.com> Reviewed-by: Richard Henderson Signed-off-by: Richard Henderson --- softmmu/cpus.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/softmmu/cpus.c b/softmmu/cpus.c index 23bca46b07..035395ae13 100644 --- a/softmmu/cpus.c +++ b/softmmu/cpus.c @@ -73,12 +73,7 @@ bool cpu_is_stopped(CPUState *cpu) bool cpu_work_list_empty(CPUState *cpu) { - bool ret; - - qemu_mutex_lock(&cpu->work_mutex); - ret = QSIMPLEQ_EMPTY(&cpu->work_list); - qemu_mutex_unlock(&cpu->work_mutex); - return ret; + return QSIMPLEQ_EMPTY_ATOMIC(&cpu->work_list); } bool cpu_thread_is_idle(CPUState *cpu) -- 2.25.1