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 4184F1F4623 for ; Mon, 7 Jul 2025 09:11:46 +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=1751879508; cv=none; b=S0J6X3XCae7ThikceUQj/3+0SX2YKSWS7eiRQplI56VZBTXkW6Rc+cztjeWZkIvu2ZfjHRQwNR0n61K+CqPrwfU90llBgImUwP6maMvw06SBrbeHqSRg2OCnfCN4S/jcN9WMBm7RLy69hMR9cW9hteYJ62QeV3pxaM3Pbtapds8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751879508; c=relaxed/simple; bh=0Tp61NqyWF5FGzGHVemsbFz0P+yecNYQl97zCv81nJ4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bStNDsNUgvNt5c52jInhkRpRY1RZFZQvED4b92VtxRBC26wnUEeUh2xrL6wfiK7pTmHLnlyKS4t83NhqD+rUz+v30xaHGEIpcOUZECXqEeP/ghQQWIY7yLPMYdp/2i4l+Y+8g+KybkHMSeWWjqNUwnLjPyL9lL3xOUj+VuBIexk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=eIkuQjMN; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="eIkuQjMN" 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=0df8zUp/oxZ4dFX7V7uLHpMSKuBUZPFHzv7dbyVP5co=; b=eIkuQjMNdbfFWr7hlEKgZaw45O aAWSlBPTF/xWfIIhp9hyyKTaX5gLx31lwYSOa4u/8hqmY/ZOvRO7ptBbiz3rmlmVMvGh67a+0mrq2 gVmYHww74r++zd7IHZ5189xMpS8n8zmBDhqOFvxPEY7Wt8OoYwjB9c2guQY/WzPQSLlD8iYmC3T7y wrJH4dO10zFOGIhQ+utcUYz1WWCWTfxElTrr586rpGPrz24BP36iRHqB3XLafSuOUXa6RfNFYT6I3 00jGyC+AZjvqjO91DcrqZo/Gm27B49cu4N0QS+qouzPuJQYOW4IGwGy9EhQyDcvIb9mRlMFUQkr2i udOzyW7g==; 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 1uYhsv-00000008RV3-13iX; Mon, 07 Jul 2025 09:11:37 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 5EB22300212; Mon, 07 Jul 2025 11:11:36 +0200 (CEST) Date: Mon, 7 Jul 2025 11:11:36 +0200 From: Peter Zijlstra To: Shrikanth Hegde Cc: linux-kernel@vger.kernel.org, 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, clm@meta.com Subject: Re: [PATCH v2 00/12] sched: Address schbench regression Message-ID: <20250707091136.GB1099709@noisy.programming.kicks-ass.net> References: <20250702114924.091581796@infradead.org> <132949bc-f901-40e6-a34c-d1d67d03d8b6@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: <132949bc-f901-40e6-a34c-d1d67d03d8b6@linux.ibm.com> On Mon, Jul 07, 2025 at 02:35:38PM +0530, Shrikanth Hegde wrote: > > > On 7/2/25 17:19, Peter Zijlstra wrote: > > Hi! > > > > Previous version: > > > > https://lkml.kernel.org/r/20250520094538.086709102@infradead.org > > > > > > Changes: > > - keep dl_server_stop(), just remove the 'normal' usage of it (juril) > > - have the sched_delayed wake list IPIs do select_task_rq() (vingu) > > - fixed lockdep splat (dietmar) > > - added a few preperatory patches > > > > > > Patches apply on top of tip/master (which includes the disabling of private futex) > > and clm's newidle balance patch (which I'm awaiting vingu's ack on). > > > > Performance is similar to the last version; as tested on my SPR on v6.15 base: > > > > > Hi Peter, > Gave this a spin on a machine with 5 cores (SMT8) PowerPC system. > > I see significant regression in schbench. let me know if i have to test different > number of threads based on the system size. > Will go through the series and will try a bisect meanwhile. Urgh, those are terrible numbers :/ What do the caches look like on that setup? Obviously all the 8 SMT (is this the supercore that glues two SMT4 things together for backwards compat?) share some cache, but is there some shared cache between the cores?