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 7D379801 for ; Tue, 8 Jul 2025 19:02:10 +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=1752001331; cv=none; b=Yz3eVthvzyDD5djGLA3cNtAq2Baa887htC1VdRFHwnVpAvM7d4vuom4tU2pBfRFQ3mQaX9ndXZ2BdeCI8rPZSYGpNk2GQSGccrNCeNoPcSngE1ajj7KRPlNjEFfwXKLTjehqMCd2n2va4YeHAoAPO5PJZGGL+peYoVr7JRUIzI0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752001331; c=relaxed/simple; bh=4PMTN+IctZyy7ZyBZURpieaQ75JXCm/LyZ+7rxRT4o8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Gu9fOH0LnbciDrbISmIcXZWtOAuqhByqT8KXQkEO0yJUT2+jB1ONJxYOd2QzN/pRPyKjTLrQenwQ7KIlUH1OGjEf6rkPIW1vaB3+4D/8xXMbFs5NZxXAWynA/mKyf4zXU1OJM0K6dM66xWHNFVQr9S09TELTBB9r05gq9LQWyd4= 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=ho2EUAyd; arc=none smtp.client-ip=90.155.50.34 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="ho2EUAyd" 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=4PMTN+IctZyy7ZyBZURpieaQ75JXCm/LyZ+7rxRT4o8=; b=ho2EUAydrQ/mPLWHTJeua6Gw+Y h5k3j7T4dDyT3eQuur6E/s4yMfVM2G0aVpo+6byXtJAQ1m+jSBMEvjypQuT9Rbgvt35Zm5LS+ie/w 5Symh4E8dHR0O3dtbg433JGqtLrMpO0VEca9x31YhBzBR3ATuv9a1WinlHwgiMaa7sHNP1KSBHFg9 CLCWhxDX3MXAJAqvBMcwneDPa0iL47At2Ib3L1Sgq3v8XFh5dK+H65lHG2A2Pgz1bRDVL3b2++bNK 5RvYfuCN6h1B1qSJgH/LblC7vLt4wuLudWARzk2EayWGDoA/wcPgezxhD6OiU7BE93ykTq5JUzqkE 99S19rJw==; 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 1uZDZq-00000000oPC-2Anv; Tue, 08 Jul 2025 19:02:02 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 25EA8300125; Tue, 08 Jul 2025 21:02:02 +0200 (CEST) Date: Tue, 8 Jul 2025 21:02:01 +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: <20250708190201.GE477119@noisy.programming.kicks-ass.net> References: <20250702114924.091581796@infradead.org> <132949bc-f901-40e6-a34c-d1d67d03d8b6@linux.ibm.com> <6e274729-af12-4e0f-9e67-5f2d5b099e99@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: <6e274729-af12-4e0f-9e67-5f2d5b099e99@linux.ibm.com> On Mon, Jul 07, 2025 at 11:49:17PM +0530, Shrikanth Hegde wrote: > Git bisect points to > # first bad commit: [dc968ba0544889883d0912360dd72d90f674c140] sched: Add ttwu_queue support for delayed tasks Moo.. Are IPIs particularly expensive on your platform? The 5 cores makes me think this is a partition of sorts, but IIRC the power LPAR stuff was fixed physical, so routing interrupts shouldn't be much more expensive vs native hardware. > Note: > at commit: "sched: Change ttwu_runnable() vs sched_delayed" there is a small regression. Yes, that was more or less expected. I also see a dip because of that patch, but its small compared to the gains gotten by the previous patches -- so I was hoping I'd get away with it :-)