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[2001:4830:134:3::11]) by mx.google.com with ESMTPS id w189si3054631qkc.64.2016.07.05.11.20.51 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 05 Jul 2016 11:20:51 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) client-ip=2001:4830:134:3::11; Authentication-Results: mx.google.com; dkim=fail header.i=@linaro.org; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) smtp.mailfrom=qemu-devel-bounces+patch=linaro.org@nongnu.org; dmarc=fail (p=NONE dis=NONE) header.from=linaro.org Received: from localhost ([::1]:57005 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKUxn-00058r-6H for patch@linaro.org; Tue, 05 Jul 2016 14:20:51 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56576) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKT3D-00078K-Du for qemu-devel@nongnu.org; Tue, 05 Jul 2016 12:18:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bKT39-0001w3-LB for qemu-devel@nongnu.org; Tue, 05 Jul 2016 12:18:19 -0400 Received: from mail-wm0-x22e.google.com ([2a00:1450:400c:c09::22e]:34221) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bKT39-0001vh-An for qemu-devel@nongnu.org; Tue, 05 Jul 2016 12:18:15 -0400 Received: by mail-wm0-x22e.google.com with SMTP id 187so27905380wmz.1 for ; Tue, 05 Jul 2016 09:18:15 -0700 (PDT) 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=fzfnfVPJfaUZfcKFJ82VRdEdo9e5ITZ+HwAmojuglkY=; b=docwefkVPcHWRfEtX6xoHWcdABRN+CB+suXZe2v7tW2UA1IKwO6WI3VeZh0IB2OnKQ 2FmJ7egxLobOlL6vy2ssCT/1DXF8AvZ8tyZW7DALGuClbrPrfTpMy4Y8nG1N8TgosvPY vGUoDki0B8TbC7cJ0mHt+DX8iYKrDvLWKys+U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=fzfnfVPJfaUZfcKFJ82VRdEdo9e5ITZ+HwAmojuglkY=; b=EHWLYWDviFp7wa4s9E46nWNahETfDWXpY+VOXStlbNa5ZKdbzQXuderUqugvpwSU4+ WG4JdVFHUdb9cqUpCnFqdLWbUP44iF+XIMQRKKSzd9pke340W1hNG+TxxervFNvCZz7p uzF5d3Qe9FX4EdqItA4ouP/oN2deZC6e6TxrQoG9agN6mPadyrN+vcvqkGM6MRPCLfdj n5ZbovDUEvnx8aiamepdg4QvUH2CDnxR4fzKM+yf3d75FPj5Pj0J0IlmumFSZIN05dd8 vKaRcCGS+VNsuNaziUwHCCkYhqFxkKvSKJjebySikFhS0rBUfrRnO+aHVAqCv13qQ3ZM BS6Q== X-Gm-Message-State: ALyK8tLZvqX8AW+rqz4Mg2Ay9M/Kvc9AbB+GvusyqynxKEJyJ4LZXhLtWAUerjDkaSYiYR7v X-Received: by 10.194.116.195 with SMTP id jy3mr18766807wjb.36.1467735494636; Tue, 05 Jul 2016 09:18:14 -0700 (PDT) Received: from zen.linaro.local ([81.128.185.34]) by smtp.gmail.com with ESMTPSA id a84sm3407705wma.0.2016.07.05.09.18.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 05 Jul 2016 09:18:13 -0700 (PDT) Received: from zen.linaroharston (localhost [127.0.0.1]) by zen.linaro.local (Postfix) with ESMTP id 9A33B3E0516; Tue, 5 Jul 2016 17:18:17 +0100 (BST) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= To: mttcg@listserver.greensocs.com, qemu-devel@nongnu.org, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, serge.fdrv@gmail.com, cota@braap.org, bobby.prani@gmail.com, rth@twiddle.net Date: Tue, 5 Jul 2016 17:18:13 +0100 Message-Id: <1467735496-16256-4-git-send-email-alex.bennee@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1467735496-16256-1-git-send-email-alex.bennee@linaro.org> References: <1467735496-16256-1-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a00:1450:400c:c09::22e Subject: [Qemu-devel] [PATCH v2 3/6] tcg: cpu-exec: remove tb_lock from the hot-path X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, Peter Crosthwaite , claudio.fontana@huawei.com, mark.burton@greensocs.com, jan.kiszka@siemens.com, pbonzini@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" Lock contention in the hot path of moving between existing patched TranslationBlocks is the main drag in multithreaded performance. This patch pushes the tb_lock() usage down to the two places that really need it: - code generation (tb_gen_code) - jump patching (tb_add_jump) The rest of the code doesn't really need to hold a lock as it is either using per-CPU structures, atomically updated or designed to be used in concurrent read situations (qht_lookup). To keep things simple I removed the #ifdef CONFIG_USER_ONLY stuff as the locks become NOPs anyway until the MTTCG work is completed. Signed-off-by: Alex Bennée Reviewed-by: Richard Henderson --- v3 (base-patches) - fix merge conflicts with Sergey's patch v1 (hot path, split from base-patches series) - revert name tweaking - drop test jmp_list_next outside lock - mention lock NOPs in comments v2 (hot path) - Add r-b tags --- cpu-exec.c | 48 +++++++++++++++++++++--------------------------- 1 file changed, 21 insertions(+), 27 deletions(-) -- 2.7.4 diff --git a/cpu-exec.c b/cpu-exec.c index 10ce1cb..dd0bd50 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -291,35 +291,29 @@ static TranslationBlock *tb_find_slow(CPUState *cpu, * Pairs with smp_wmb() in tb_phys_invalidate(). */ smp_rmb(); tb = tb_find_physical(cpu, pc, cs_base, flags); - if (tb) { - goto found; - } + if (!tb) { -#ifdef CONFIG_USER_ONLY - /* mmap_lock is needed by tb_gen_code, and mmap_lock must be - * taken outside tb_lock. Since we're momentarily dropping - * tb_lock, there's a chance that our desired tb has been - * translated. - */ - tb_unlock(); - mmap_lock(); - tb_lock(); - tb = tb_find_physical(cpu, pc, cs_base, flags); - if (tb) { - mmap_unlock(); - goto found; - } -#endif + /* mmap_lock is needed by tb_gen_code, and mmap_lock must be + * taken outside tb_lock. As system emulation is currently + * single threaded the locks are NOPs. + */ + mmap_lock(); + tb_lock(); - /* if no translated code available, then translate it now */ - tb = tb_gen_code(cpu, pc, cs_base, flags, 0); + /* There's a chance that our desired tb has been translated while + * taking the locks so we check again inside the lock. + */ + tb = tb_find_physical(cpu, pc, cs_base, flags); + if (!tb) { + /* if no translated code available, then translate it now */ + tb = tb_gen_code(cpu, pc, cs_base, flags, 0); + } -#ifdef CONFIG_USER_ONLY - mmap_unlock(); -#endif + tb_unlock(); + mmap_unlock(); + } -found: - /* we add the TB in the virtual pc hash table */ + /* We add the TB in the virtual pc hash table for the fast lookup */ atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb); return tb; } @@ -337,7 +331,6 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu, always be the same before a given translated block is executed. */ cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); - tb_lock(); tb = atomic_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)]); if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base || tb->flags != flags)) { @@ -361,9 +354,10 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu, #endif /* See if we can patch the calling TB. */ if (*last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { + tb_lock(); tb_add_jump(*last_tb, tb_exit, tb); + tb_unlock(); } - tb_unlock(); return tb; }