From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CB6361E0DCB for ; Mon, 22 Sep 2025 10:59:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758538770; cv=none; b=nhS0qYZkRTRTzNxQcvYEBTcjz8io1oEzTTz5BPOKQJ8qVDjix6yHt7Ji9Hcz7zb0ZpwJ9U+V40SyBJcK5mbU7Dg7yM72+vDEBYE4/7tLHZlPDbHYeDHkz72C788zF7qQR9eEIJqsp77IUSM/keyN7NIbF5C97Ns2LIYbVt+WDT4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758538770; c=relaxed/simple; bh=o1lDqlMsk1yFq192R+5MhB3fFWbg6PgdL1q31dVJ8go=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=K6VgnKUR2RiggAdleufYHPA2VdC2TNaWkKKs4nVoxZzaRZoJXk6L902OzVskfifFdPlHw4t2+WTwmzjFBAlPjY9eHOjTfb8eu7JRER0JRnZtl3RTaJjIuyjuYoZJL8FdqV7trtehrXIr4PvtpaHnoIwk7EtEz1W1jJaBPlCMB+Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NJHyDnug; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NJHyDnug" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7644DC4CEF0; Mon, 22 Sep 2025 10:59:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758538770; bh=o1lDqlMsk1yFq192R+5MhB3fFWbg6PgdL1q31dVJ8go=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NJHyDnugZam9/507Uer/BvX23Rt/Zp0pHkiESat+GwwtnWps2p1Sjrpudl9DV8NAx S4kku1VpodBdzRdhUrVzMoEsgeFc3HFPmf4mi59eTjMX8gH2LqWV28ZSROcOj+S38D B8TiNfCAA6O0xueTRmuO+ht9Dk/fsoxxZFlDDl2eWVrINFaIQDlso2i9qp+XKtF7Vv igAWDWAEFrWLdaiZH7l+LX+HQt5gmn8WiVKt9UAToaewkq3mXH9eyoUE5mxFxdJFs/ pWoiE1gmzCafpQLJXq1sKUJ07+zdq1eU2qmiBD1Vc6JK0SowncgqnInGpMsQZJQRwF F383Vse4cjD3g== Date: Mon, 22 Sep 2025 11:59:26 +0100 From: Will Deacon To: Li Qiang Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: add unlikely hint to MTE async fault check in el0_svc_common Message-ID: References: <20250919033327.1942730-1-liqiang01@kylinos.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250919033327.1942730-1-liqiang01@kylinos.cn> On Fri, Sep 19, 2025 at 11:33:27AM +0800, Li Qiang wrote: > Add unlikely() hint to the _TIF_MTE_ASYNC_FAULT flag check in > el0_svc_common() since asynchronous MTE faults are expected to be > rare occurrences during normal system call execution. > > This optimization helps the compiler to improve instruction caching > and branch prediction for the common case where no asynchronous > MTE faults are pending, while maintaining correct behavior for > the exceptional case where such faults need to be handled prior > to system call execution. > > Signed-off-by: Li Qiang > --- > arch/arm64/kernel/syscall.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Does this result in a measurable performance difference? Will