From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 E6E269443; Fri, 17 Jan 2025 16:25:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737131118; cv=none; b=lcZiK6vWsM/3mjeCKrqFnakbQ/z3j11EdPj59mlVaBElG3rvvWJJdOrhYlIOOuHkxbXK+egOjeTGAf+x+qUW6HaOmMM36O+WEK+PEqvgK2RwymupshOL+3Mus8onz/gsW6jWyFsyY+ppvwCQiW+96THk+gX25VS6C50mFNPeuV4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737131118; c=relaxed/simple; bh=I8EpZonizEFVHQxzlw54g7V7LZ0QLS1FMKRkuMi7P54=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VpHH176b5rY35leHFG+WwBeZ2sFl7Hnor1gW5TONTUNcPIzoh1yDfh/G4xBBQmpqMbNoft06x0/GZ82PfGo1QITx+XYKkrxGDw6KIpsuNN4F7K3BQdExfy2XOvuac3/hX1rZyntfonhqMY68yN9tZ0XiSQQDUik8Cki3CyC4TJ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=cEA4SQLT; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="cEA4SQLT" Received: from [IPV6:2601:646:8080:c1f1:e386:c572:17d3:6ddc] ([IPv6:2601:646:8080:c1f1:e386:c572:17d3:6ddc]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 50HGOmrR037200 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Fri, 17 Jan 2025 08:24:48 -0800 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 50HGOmrR037200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2024121701; t=1737131089; bh=cYqdHxwjXLBzNcwPlVzG9npiTRsahmwSbuxX8PL3YNA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cEA4SQLT7qqu68qTb1s7N19d54GgYTOnb05jFFEz8+IE7pte79qBIPqvAAtnCWzJp 3Q+aE6kacfV1NgbFj7eNswpXrjeWDhSVo/fyvWQdfd545KOX6bT+akV+Ata1+iYsDA 0kFMyeK1SmXzAqQfK75wrmuX1XXe+1hG7FzygKsK/J3njHq9kupQt1Q59EZms77SwN Tu9HMuJELx7Ks5C002S4DOS4R4jr5z//+LGs+2wG4GEZb1e1GeyeY+NKQtyNu0b6M8 83UeS1jplJ57cW0LfxILxk1dTbaxQM7h5rO3np3bDPAejTeFmmgSPKENA+6krCAbJA DJ7pctuSPh6cg== Message-ID: Date: Fri, 17 Jan 2025 08:24:43 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/fred: Optimize the FRED entry by prioritizing high-probability event dispatching To: Ethan Zhao , Xin Li , Ethan Zhao , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: tglx@linutronix.de, dave.hansen@linux.intel.com, x86@kernel.org, andrew.cooper3@citrix.com, mingo@redhat.com, bp@alien8.de References: <20250116065145.2747960-1-haifeng.zhao@linux.intel.com> <417271c4-0297-41da-a39b-5d5b28dd73f9@zytor.com> <05b13e99-c7e5-4db7-90bd-a89a91f4e327@zytor.com> <56b92130-7082-422c-952c-9834ebdb7268@linux.intel.com> <4d485294-959b-42a6-a847-513e8e3d0070@zytor.com> <33b89995-b638-4a6b-a75f-8278562237c4@linux.intel.com> Content-Language: en-US From: "H. Peter Anvin" In-Reply-To: <33b89995-b638-4a6b-a75f-8278562237c4@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit > > In short, seems that __builtin_expect not work with switch(), at least for >  gcc version 8.5.0 20210514(RHEL). > For forward-facing optimizations, please don't use an ancient version of gcc as the benchmark. -hpa