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 12F9D304BB7 for ; Mon, 12 Jan 2026 07:47:06 +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=1768204027; cv=none; b=CL9Kg1Bxa6ulgJO1isV7NXUc1iPaN/bGqCjv+En/W8C9BrrJ3RQaVr3wANFlqFosk1AwGcj/3g2nYOah1eylNQ8tzc2HNk4V0nSmlYBl8DVeYw+rrc2+ScftV/mmdkQ1l8RUFGOo0CTl/v8SebE/CPRNpTClM5sYRK5YscpV2w4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768204027; c=relaxed/simple; bh=LDxxQM9G0C21NNfhoFJf2C3EpaRorZxv8S7YETIKTnE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Sh0NH2vzTMyiI/naFkG2LqW/uCHt/otar79ycy8raS1QpnQrXO6baDWiCMZwyfOGzcKH5yrPI9lxdJESVc6v9x40W1ijGobaIbQiBaf4ubWhLWkQGeaDhaHHq+JbBdQxGFdEdoXW79/Jc4rO0dvPwOgzInl9jGNYJ8tR018RdrM= 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=narCZXIf; 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="narCZXIf" 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=dQ9CHy0v1g/1UWt7p2cZOXsr2WmFqE4zJl1y0qR68M0=; b=narCZXIfXxglCTazKAJNMf8AQA 65drfQGEDWDPz4TTf1Pf0MsWmbggeFnLBu52nFJ6fnUwuSSImn28Iav3AJNo7hrNBJ6MKDHDg2+be EABlQCwgcTBu6DSGZh6jV/mKWpl2S0HSbHBer0J1ZnsFm3Qo3GcelGnrluLXW8rtzbfOYnEMdGR9z ZdnFCp3uUE2zZitQqDELcoAMEroWxQwoMh6c/B4Qzs6ZdLGQgJZTduutiViTFQY0yUvEeMQ97yr2v jR0anPPSJFIPQXJ67S/+GJFS5B/F7DmunmQcu3G0F1wrFVy8D5HkEkPfYp5dFxtZ2Lh3WwmTg5v13 bm7g/qjA==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vfCdj-00000000By8-37YR; Mon, 12 Jan 2026 07:47:04 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 3F9B53030B0; Mon, 12 Jan 2026 08:47:03 +0100 (CET) Date: Mon, 12 Jan 2026 08:47:03 +0100 From: Peter Zijlstra To: Ryan Roberts Cc: Mel Gorman , Dietmar Eggemann , x86@kernel.org, linux-kernel@vger.kernel.org, Aishwarya TCV Subject: Re: [REGRESSION] sched/fair: Reimplement NEXT_BUDDY to align with EEVDF goals Message-ID: <20260112074703.GB830755@noisy.programming.kicks-ass.net> References: <20251112122521.1331238-3-mgorman@techsingularity.net> <176339661525.498.7070393041762616565.tip-bot2@tip-bot2> <4b96909a-f1ac-49eb-b814-97b8adda6229@arm.com> <756efd17-682f-4ffc-b8d9-dbb2517bc152@arm.com> <051285c7-56c0-455d-ab3e-9959edb5d13f@arm.com> <6c137b30-d5f7-4dd9-9699-d7e22c174285@arm.com> <63d22eb9-b309-4d11-aa56-3f1e7e12edb1@arm.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: <63d22eb9-b309-4d11-aa56-3f1e7e12edb1@arm.com> On Fri, Jan 09, 2026 at 10:15:46AM +0000, Ryan Roberts wrote: > Here are the updated results, now including column for "revert #1 & #2". > > 6-18-0 (base) (baseline) > 6-19-0-rc1 (New NEXT_BUDDY implementation enabled) > revert #1 & #2 (NEXT_BUDDY disabled) > revert #2 (Old NEXT_BUDDY implementation enabled) > > > The regressions that are fixed by "revert #2" (as originally reported) are still > fixed in "revert #1 & #2". Interestingly, performance actually improves further > for the latter in the multi-node mysql benchmark (which is our VIP workload). > There are a couple of hackbench cases (sockets with high thread counts) that > showed an improvement with "revert #2" but which is gone with "revert #1 & #2". > > Let me know if I can usefully do anything else. If its not too much bother, could you run 6.19-rc with SCHED_BATCH ? The defining characteristic of BATCH is that it fully ignores wakeup preemption.