From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 08DB718C3D for ; Tue, 13 Aug 2024 17:33:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723570387; cv=none; b=JfSmjq3HvxuosxFMbQrtEIswB6KJewPnWO7eS4GVHQE3UTKtZT+jPl13CIdVC0O3useF6Bs/GK7al+hAKUmeXkxVT1Tagv9WBHjJvXD7ndqtZTdLI5DyBeEzv0kfpfaDXZ8vwInIczDwxXD4HB9TZUdfoVk8+0Wh6bW68r2N05c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723570387; c=relaxed/simple; bh=MIlrSk7SgXvMrIEjjWC8Je4dhxIyuPX/L2G7QvgIAjo=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=WUY5DVBZHskSBstaL311EKjiur7oTSDQXu2KbxPy7L7w0Zhut4+klmcRxgl3xRzqbsuUGmgLWVSgnNregw3y4SrpxPgNli5sdb/MQtnP2ddaesP5oKfIHXk7cvUNQF+499OctrGqNVClM8hkUngXjoLLBlEn9xKuUtIQH8EInFc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=bU6KibrZ; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=+Yk5DG2t; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="bU6KibrZ"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="+Yk5DG2t" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1723570380; 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: in-reply-to:in-reply-to:references:references; bh=CCeddw978sFZNifYTaABplpibXMqPeWXWLsqy4nR1LI=; b=bU6KibrZLcT+dRuYXHs59WqGHWD1Bxu/QMm/LxiTzJ0pxmY+hQeVs+9cURfpbR96ye6AIT 65qd69QPlFcb/z9j9Od9oER7QrnsE6hbSWZamyFR3bASIa97MxKksfSVBkLu8bM2cQIJsP GQUxim5ytCRBO0mqpmyJtLGcO+vFVzBBuDoL79C8gw4famC43uyyY5/6QCQSGRgcMQRHkC UOQQCHx1B45yKSPFRL3UXzScRYVYagN9Fu0iOXtr1/dVG+NdZM3glsmZ3CR/S1b/p6d7b0 2ztzBe1mXcYN3ehbc+fMWQbjWOXO0qPOmUtQJ/tkw8dT0K3+DWL31GeBTK+0FA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1723570380; 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: in-reply-to:in-reply-to:references:references; bh=CCeddw978sFZNifYTaABplpibXMqPeWXWLsqy4nR1LI=; b=+Yk5DG2tsARz6KagXaDT8SHmXod7ExkoaeHVtXDkf4s7oVQ88JjcpR32sUQg64JVGVoZEu fGf0IbyuYBE3TuCg== To: Qiuxu Zhuo Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, x86@kernel.org, qiuxu.zhuo@intel.com Subject: Re: [GIT pull] x86/urgent for v6.11-rc3 In-Reply-To: <20240813031522.4544-1-qiuxu.zhuo@intel.com> References: <87le12rw26.ffs@tglx> <20240813031522.4544-1-qiuxu.zhuo@intel.com> Date: Tue, 13 Aug 2024 19:33:00 +0200 Message-ID: <87o75wpbub.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Tue, Aug 13 2024 at 11:15, Qiuxu Zhuo wrote: >> From: Thomas Gleixner >> On Sun, Aug 11 2024 at 11:07, Linus Torvalds wrote: >> > I doubt it actually matters, since I think this all is fundamentally >> > just in the slow-path, so the "do a branch or a no-op" is likely >> > entirely in the noise even if I followed the code right. But it looked >> > off to me. >> >> It is off and yes it won't matter much in the slowpath maze. > > static_branch_unlikely() matches that 'virt_spin_lock_key' is set to false > in default after the commit, > > e639222a5119 ("x86/paravirt: Fix incorrect virt spinlock setting on bare metal") > > although it offers little performance benefit since it is in the slow path. > > Thomas, do you think it's worth making a patch to convert static_branch_likely() > to static_branch_unlikely() for this check, as suggested by Linus? > If so, I can assist with this. Sure, but I'm not so sure that it actually matters and makes a measurable difference. Thanks, tglx