From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 22CE8303A03 for ; Fri, 14 Nov 2025 09:35:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763112957; cv=none; b=AArEQWcgbUufHyCKFoGrBvW/iupC3r5ZWq92w6Kg1I5D3cQ2nIg9LM2hRFN1KcwMRhfWOUrKk7CDYXFTBPCJc0c+7lwzADzEx+WhP6+C7Ab3vNkseoe2wKaixQJxzzHJ53R0KCDppoBnrwpxEgonkVS9mIRWA9YoibG19Bt6WLw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763112957; c=relaxed/simple; bh=Ip3Dc3vJTdpMM6W/CWfBtZ+vVIg/9q7reu98/0xjZAQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bgkTAwyTBDsi2eTJ+VhSpNOzg4phOgyPna+uG5gZIf8ZG+C7O9meD+Az59BNxUuDhstd58QOBUGhfQ8U9LtaI4OeHZQu/o9sehc7pEymOeYEDfDPACXRcPZuqJ+z32dZ+cguZfDxxAF4A5A+Rwt0dujMtu9bhi1oP6S067HSeso= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=HFhcPKP5; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="HFhcPKP5" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=EPBBssAbRCdO4NRp/tKELYD7tjIF4/8wFfAGoWw1Gdc=; b=HFhcPKP5Awj2GiPg+08X5R+t/I kNgFAp17+lGMPGeyv8Hc3UuE9sls0KSSinl98ejbW3YxYyvj2ptrAURzJh055iWjJPPFKbvnftzQM wIYinRY3Vz64/YCAomCC+C5PFRP/k/eDdLwKldjXKB2wV3HgWspEgX73vwUdBX75/uiEpLiWFrbNx ov+jhX2Gvij3D0eFb68YFy7OvWMlTr8KB4b3tCTNeDpncTxaPYTIHPjct9g8h51HZgeXd1T2M6GQu eocgckIF6tqiKSYC7gQ2q01Ved74psBaH7Vqv3SK8RsrpJ/0LMdaMkwdBFFd8od2NTGCkY22GNljG f5UsLBSw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vJpLq-00000002Cnt-2LW0; Fri, 14 Nov 2025 08:40:15 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 44DC5300325; Fri, 14 Nov 2025 10:35:40 +0100 (CET) Date: Fri, 14 Nov 2025 10:35:40 +0100 From: Peter Zijlstra To: Shrikanth Hegde Cc: mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, Chris Mason , Joseph Salisbury , Adam Li , Hazem Mohamed Abuelfotoh , Josh Don Subject: Re: [PATCH 4/4] sched/fair: Proportional newidle balance Message-ID: <20251114093540.GF3245006@noisy.programming.kicks-ass.net> References: <20251107160645.929564468@infradead.org> <20251107161739.770122091@infradead.org> <588c0150-4a2c-414f-9fde-3d18b2bbb3ad@linux.ibm.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=us-ascii Content-Disposition: inline In-Reply-To: <588c0150-4a2c-414f-9fde-3d18b2bbb3ad@linux.ibm.com> On Wed, Nov 12, 2025 at 09:12:57PM +0530, Shrikanth Hegde wrote: > > > On 11/7/25 9:36 PM, Peter Zijlstra wrote: > > Add a randomized algorithm that runs newidle balancing proportional to > > its success rate. > > > > This improves schbench significantly: > > > > 6.18-rc4: 2.22 Mrps/s > > 6.18-rc4+revert: 2.04 Mrps/s > > 6.18-rc4+revert+random: 2.18 Mrps/S > > > > Could you please share the schbench command? > > I see command like "schbench -t 90 -r 30 -i 30" running on 60 core regress. > Will do more iterations to confirm it (to be sure it is not run/run variation) This was: schbench -L -m 4 -M auto -t 256 -n 0 -r 60 -s 0 from the original thread: https://lkml.kernel.org/r/20250626144017.1510594-2-clm@fb.com > > + if (sd->newidle_call >= 1024) { > > + sd->newidle_ratio = sd->newidle_success; > > + sd->newidle_call /= 2; > > + sd->newidle_success /= 2; > > + } > > Would it be better to >> 1 ? or compiler takes care of it? I would be very disappointed if our compilers don't do this.