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 8375219AD5C for ; Wed, 7 May 2025 16:23:01 +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=1746634981; cv=none; b=qDCvDShvTUmC9MqSm/tNNqTHfgduxw9gHBLzOCsh36WK4kvTqm8X/InPXEYxkA3mxA6uUwL5qmU3h7VTlc5zmjIMoP6Rh/Rq9UhbUtqepckD0WYbi69dYJVPwweGhygT7y7AO6TDoBdL7ZYui9/oX30ZvuisJ5cvZuy0rLqx/L0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746634981; c=relaxed/simple; bh=Ol2/vY77MjaTU3wvjpzVZP9L+fNJkq5zxkYL/AYyCVs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=foAKzsAaIus5JVUlTQW9irkXFrcsTYJxcwy4/UrU2QrxeKFY+CYPOPfUL8gSwDNaKbhmUR5M+n7VH0kbf1kJWmOBTMNIwZ4HLwNFuJzFfMNpzkSl0c70LTSuOiLZHiUx8CFaKUzH7y76KFKVk2dm9/x65o5t6e5xu1KxiJTlp28= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Fnl0Zr7a; 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="Fnl0Zr7a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E63DC4CEE2; Wed, 7 May 2025 16:22:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746634981; bh=Ol2/vY77MjaTU3wvjpzVZP9L+fNJkq5zxkYL/AYyCVs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Fnl0Zr7ay/Tu/dN0Ab8/WMC7OTuXzD0T6qALw5E/IT/5sjHXpioZE9UaVUxkaEE8w 0OWT0q4JohtuWQtNPZ1CBGoPcrVX7oPUw0eOlq2V7SJYiQ3hsVqIwCEww5bAfnXcP4 lebX9jGOeZJNbPLepIBOzkdE0e4tbye3xMbLzlIHDPyrR9SsH4Te6zHmXKqq4oCRVa /lWDIip8eeUqhDzfXmk8XIGCDs4TKvdREcSaWw8/Ww+ImCPo7PJiDlX6vzdJpoqYOe mf7+0jJ0MuslvG0HH3gT3ZVBnPzorIOIuXARYL8qbAQobtiBgX+617bTmSYeue/Y8Q oZIcbcLQ4p6RQ== Date: Wed, 7 May 2025 18:22:55 +0200 From: Ingo Molnar To: Yafang Shao Cc: Peter Zijlstra , ardb@kernel.org, arnd@arndb.de, bp@alien8.de, dwmw@amazon.co.uk, hpa@zytor.com, linux-kernel@vger.kernel.org, michal.lkml@markovi.net, tglx@linutronix.de, torvalds@linux-foundation.org, vkuznets@redhat.com, yamada.masahiro@socionext.com Subject: Re: [PATCH 13/15] x86/kconfig/64: Enable popular scheduler, cgroups and namespaces options in the defconfig Message-ID: References: <20250506170924.3513161-14-mingo@kernel.org> <9b31f1df-7dc6-468b-9418-0b13239df8bc@gmail.com> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: * Yafang Shao wrote: > On Wed, May 7, 2025 at 3:06 PM Ingo Molnar wrote: > > > > > > * Yafang Shao wrote: > > > > > Hello Mingo, > > > > > > > +CONFIG_VIRT_CPU_ACCOUNTING_GEN=y > > > > +CONFIG_IRQ_TIME_ACCOUNTING=y > > > > > > Enabling CONFIG_IRQ_TIME_ACCOUNTING=y can lead to user-visible behavioral > > > changes. For more context, please refer to the related discussion here: > > > https://lore.kernel.org/all/20241222024734.63894-1-laoar.shao@gmail.com/ . > > > > Yeah. I actually agree with your series. It (re-)includes IRQ/softirq > > time in task CPU usage statistics even under IRQ_TIME_ACCOUNTING=y, > > while still keeping the finegrained IRQ/softirq statistics as well, > > correct? > > Correct. > > > > > The Kconfig option is also arguably rather misleading: > > > > config IRQ_TIME_ACCOUNTING > > bool "Fine granularity task level IRQ time accounting" > > depends on HAVE_IRQ_TIME_ACCOUNTING && !VIRT_CPU_ACCOUNTING_NATIVE > > help > > Select this option to enable fine granularity task irq time > > accounting. This is done by reading a timestamp on each > > transitions between softirq and hardirq state, so there can be a > > small performance impact. > > > > It only warns about a small performance impact, but doesn't warn that > > CPU accounting is changed in an incompatible fashion that surprises > > tooling... > > Yes, this breaks our userspace tools. Okay, so 2 out of your 3 fixes are upstream already: 763a744e24a8 ("sched: Don't account irq time if sched_clock_irqtime is disabled") a6fd16148fdd ("sched, psi: Don't account irq time if sched_clock_irqtime is disabled") But we don't have this one yet: [PATCH v8 4/4] sched: Fix cgroup irq time for CONFIG_IRQ_TIME_ACCOUNTING https://lore.kernel.org/r/20250103022409.2544-5-laoar.shao@gmail.com which is also essential to fully fix the tooling regression, right? I think this last patch fell between the cracks, I didn't see any fundamental objections against the fix. Since the patch does not apply cleanly anymore, mind sending a fresh -v9 version against v6.15-rc5 or so? Thanks, Ingo