From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 815A620DE3; Wed, 24 Dec 2025 13:26:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766582784; cv=none; b=A0BvXLvF2cYrQTJ0dw0WgZcmlnN8b6YkDdDH9b3baTlM+TLn3QzqGX6S9d95GSpo1lG5KJxX2YWnlzecrlOzafF12P61KL8k5QOkWeBhzUOlgIGsd/YSMMFUClVLtgMbOhHaLFgTBpk1sgdZNkM8lcjC5m57PW96iF80cxVIEiM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766582784; c=relaxed/simple; bh=H+zCL2UnrgIaQDe/zx6zgPOYKGNAmgwr+oXBVxDBVXo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RxWnPJ0Mg5b/e6Zg1OK7wXR7NuHN64BA5QfVfCF776gDNh4//eZaYTJTczX0x4zomvcJk/5m7L9y37MM7kM9xhFdtt0zEqTD3CMKpxwMffXGqrX44qh4Mdtj0KNXDEhuiG+B15akPz+/gmRFnOX5+dDQBCCbA8YWLVTtB7EWCPo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AD70D339; Wed, 24 Dec 2025 05:26:14 -0800 (PST) Received: from [10.57.46.118] (unknown [10.57.46.118]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3DA333F694; Wed, 24 Dec 2025 05:26:20 -0800 (PST) Message-ID: <2463b494-66dd-4f0b-9ce7-4f544a41ecbf@arm.com> Date: Wed, 24 Dec 2025 13:26:18 +0000 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: [report] Performance regressions introduced via "cpuidle: menu: Remove iowait influence" on 6.12.y To: ALOK TIWARI , rafael.j.wysocki@intel.com, daniel.lezcano@linaro.org Cc: gregkh@linuxfoundation.org, sashal@kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-pm@vger.kernel.org References: Content-Language: en-US From: Christian Loehle In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 12/24/25 12:18, ALOK TIWARI wrote: > Hi Christian, > > > On 12/3/2025 11:01 PM, ALOK TIWARI wrote: >> Hi, >> >> I’m reporting a performance regression of up to 6% sequential I/O >> vdbench regression observed on 6.12.y kernel. >> While running performance benchmarks on v6.12.60 kernel the sequential I/O vdbench metrics are showing a 5-6% performance regression when compared to v6.12.48 >> >> Bisect root cause commit >> ======================== >> - commit b39b62075ab4 ("cpuidle: menu: Remove iowait influence") >> >> Things work fine again when the previously removed performance- multiplier code is added back. >> >> Test details >> ============ >> The system is connected to a number of disks in disk array using multipathing and directio configuration in the vdbench profile. >> >> wd=wd1,sd=sd*,rdpct=0,seekpct=sequential,xfersize=128k >> rd=128k64T,wd=wd1,iorate=max,elapsed=600,interval=1,warmup=300,threads=64 >> >> >> Thanks, >> Alok >> > > Just a gentle ping in case this was missed. > Please let us know if we are missing anything or if there are additional things to consider. > Hi Alok, indeed it was missed, sorry! The cpuidle sysfs dumps pre and post test would be interesting like so: cat /sys/devices/system/cpu/cpu*/cpuidle/state*/* for both would be helpful so I can see what actually changed. Or a trace with cpu_idle events. Additionally a latency distribution of the IO requests would be helpful to relate them to the cpuidle wakeups. Thanks, Christian