From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ms.lwn.net (ms.lwn.net [45.79.88.28]) (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 40EDC3624AB for ; Mon, 27 Jul 2026 17:12:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.79.88.28 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785172379; cv=none; b=b9xb5HwIUezkXqaNi0v9ZYesq2JRRYGJxrZQrg3hBfYKmJ3S26Sj7swy0A8lWKByB3qVuM6l25f3gmCcuTkgsvAw48BHk+i7hUrnA/nvAgQRQl0FCX94iBB9r0gZKOuofKKj55P9MaxZkAuAJ8f0VWE4Xvtap2MI23CEpwUyUkw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785172379; c=relaxed/simple; bh=GUvg1OvMWeBo17iFOZYqPbjz7WOOgO7fLmvZ5xfMdY8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=XtwCUsfSsvxDhDaZBwo6GoX0zpvMgTf+6iNbqdeLB4ASogxbGdcb6skbjUMf6Nk7zFNLDXKE7dVoLaY5xWTIBQhYu2VeyDsG9sYlFXmNhatA1AHqUVQmhBd+JWxp++QlPtlKcZpiZvO1h/nI+FajPiOCgNDSAuJmwCy756hcr6M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net; spf=pass smtp.mailfrom=lwn.net; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b=H1z9+Tqo; arc=none smtp.client-ip=45.79.88.28 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lwn.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b="H1z9+Tqo" DKIM-Filter: OpenDKIM Filter v2.11.0 ms.lwn.net 3E96F408B2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lwn.net; s=20201203; t=1785171848; bh=KuVSC8RadY+LK86Bwdw/4JgOl2/sK70FYFnSHTYlTgk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=H1z9+TqoYuss7JjoQTGjCaRVPO0aDz8CHY6bp06sEg39a1jzsgRFiNb8/04tduQeN fDW67ArT0WivAkcnHiJX1/ovInBmNT2LoDOOkJiXQ4jY+pME+GW0NSWsQ/P8We5n6e R5y7dkVo9WbPsDICbaJFDVbQsEaRSKdFrnOyI+7OMVVx4/YHFmyvfjfHUaIFjt1hR+ vxCM134thZGB9jEEemPVsUyb+cxfjU8Y/Enl4PGDAUxRHmGcRNqeM6LOzUhZQLgwC3 SV+eusI42GzLDGkSMWbODTZxs80qM+c0SX2yowTKb6os53cl9ldWm32kh4OyQhWsIK mWgShsoT4kYVQ== Received: from localhost (unknown [IPv6:2601:280:4600:27b::1fe]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 3E96F408B2; Mon, 27 Jul 2026 17:04:08 +0000 (UTC) From: Jonathan Corbet To: Xavier Claude , linux-doc@vger.kernel.org Cc: Xavier Claude , linux-mm@kvack.org Subject: Re: [PATCH] docs: add example for psi info In-Reply-To: <20260726134037.24412-1-contact@xavierclaude.be> References: <20260726134037.24412-1-contact@xavierclaude.be> Date: Mon, 27 Jul 2026 11:04:07 -0600 Message-ID: <87tspkicu0.fsf@trenco.lwn.net> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Xavier Claude writes: > Provide an non zero example with explanation of the values. > > Signed-off-by: Xavier Claude > --- > Documentation/accounting/psi.rst | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) This may be a good change, but you really want the memory-management developers to look at it...adding linux-mm in the hopes that might make it happen. Thanks, jon > diff --git a/Documentation/accounting/psi.rst b/Documentation/accounting/psi.rst > index d455db3e5808..dadab65f872d 100644 > --- a/Documentation/accounting/psi.rst > +++ b/Documentation/accounting/psi.rst > @@ -64,6 +64,20 @@ as well as medium and long term trends. The total absolute stall time > spikes which wouldn't necessarily make a dent in the time averages, > or to average trends over custom time frames. > > +For example, the following output:: > + > + some avg10=7.52 avg60=12.59 avg300=24.82 total=2128219913967 > + full avg10=5.70 avg60=10.56 avg300=22.40 total=2014527537356 > + > +This means that for the last 10 seconds, 5.7% of the time (so 0.5 > +seconds) was lost on cpu cycles because all the running processes where > +waiting on the resource. On the same period, some tasks where not > +schedulable during 7.5% of the time (so 750ms) because they were waiting > +on the resource. But for a longer period of 300 seconds, we see that > +more than 20% of the time (so 60 seconds) is wasted due to resource > +contention. Moreover, since the total time wasted because tasks were > +waiting on the resource is 2014527.5 seconds. > + > Monitoring for pressure thresholds > ================================== > > -- > 2.55.0