From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 324A01A680F for ; Tue, 31 Mar 2026 09:29:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774949365; cv=none; b=VVy9VvIuWPmzWe3FBjBPsNKHJbtKcVb491dTBiGcut38/aKDgGmkofnhFs7Ep9cfcCFuEP+S8kujo4PIXAPjQB8DdcCjs5B1/aK0WziuvQGzmZ0OF2hse/rKysJZqAkXXMeH7cIMrzKoGCuQOzGu/EMwqwCmZTpYxlk5+QmB4mo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774949365; c=relaxed/simple; bh=oD+L9Ek4f1JdDtEfNVCDqrG7apKPqUlVKSGCFRnwD3s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FkL2Asg04ceM+kBl5SKENCXO2LWNKyaUJfxAfrPxdwbYb9JVKaHSb8W/zcnkpaS83xMqqb49H6BwxsvPV2KfW4292KjwLAZpebf3VO1YalEvQTMbNhqHFmrcwSE7Hkc+5vNRz2MtHrfrI6ZGKYz+ZSGaQxjBvbnlzes0aAeLW8w= 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=lZlCiQEE; arc=none smtp.client-ip=90.155.50.34 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="lZlCiQEE" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=/haL78qTntojyuoNZ1IW67fwT/JqMQ37n1oDcL+DYpQ=; b=lZlCiQEEZBH6ertjajMTff0avm etD2NXaFa+j1/gY4I0ycs0sy3no7beRVKZOt5I1DZwtDneS04PR0i2i0AiI5uugcMZgqTr84+sbLd JuTnRvmFXxbI9Xb+g2UwYKr39qL5G2vTQKCkBG4GXUZ89x7Nd6baU363+UnvFavRwo7oYAgUtltkO r6lgUsaS6vHliC5evtEHVnFJEzPJOUVMNf5y0Opyq4VcLE3IQa6tyGjQQOLEk4w7CI0Uvj+aAsqvE o0WsMGFGL/aa6eNzPW8GnIWrHKZi5DiDbKVL2xiybJwskh5NDAODjvT9xE2APo9s1++6JBEkR7bOR JQWeNcjg==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1w7VPK-00000008HYg-2arI; Tue, 31 Mar 2026 09:29:10 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 5A7C6300400; Tue, 31 Mar 2026 11:29:09 +0200 (CEST) Date: Tue, 31 Mar 2026 11:29:09 +0200 From: Peter Zijlstra To: K Prateek Nayak Cc: John Stultz , mingo@kernel.org, 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, wangtao554@huawei.com, quzicheng@huawei.com, dsmythies@telus.net, shubhang@os.amperecomputing.com, Suleiman Souhlal Subject: Re: [PATCH v2 1/7] sched/fair: Fix zero_vruntime tracking Message-ID: <20260331092909.GQ3738010@noisy.programming.kicks-ass.net> References: <20260330101018.GN3738786@noisy.programming.kicks-ass.net> <73dab51a-650f-4c82-9e73-13236b2a26c2@amd.com> <20260330144005.GP3738786@noisy.programming.kicks-ass.net> <20260330191108.GU2872@noisy.programming.kicks-ass.net> <20260331070822.GC3739027@noisy.programming.kicks-ass.net> <20260331071402.GN3739106@noisy.programming.kicks-ass.net> <19667aac-99c4-40cf-bc0a-b1e6b9d32ede@amd.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: <19667aac-99c4-40cf-bc0a-b1e6b9d32ede@amd.com> On Tue, Mar 31, 2026 at 02:19:54PM +0530, K Prateek Nayak wrote: > On 3/31/2026 12:44 PM, Peter Zijlstra wrote: > > On Tue, Mar 31, 2026 at 09:08:23AM +0200, Peter Zijlstra wrote: > >> On Tue, Mar 31, 2026 at 06:08:27AM +0530, K Prateek Nayak wrote: > >> > >>> The above doesn't recover after a avg_vruntime(). Btw I'm running: > >>> > >>> nice -n 19 stress-ng --yield 32 -t 1000000s& > >>> while true; do perf bench sched messaging -p -t -l 100000 -g 16; done > >> > >> And you're running that on a 16 cpu machine / vm ? > > > > W00t, it went b00m. Ok, let me go add some tracing. > > I could only repro it on baremetal after few hours but good to know it > exploded effortlessly on your end! Was this a 16vCPU VM with the same > recipe? Yep. It almost insta triggers. Trying to make sense of the traces now.