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 01D252C0F6D for ; Tue, 27 Jan 2026 08:44:21 +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=1769503463; cv=none; b=ZX18u10z1T/r8A6TDIegm/IoCQcRYE44ivw6GXEoZmaFemDWNsqqCW/5p5AYOxTG5SQ1hjG0DTx3zvxFZw9QfzIDV/Hqaj6exzSIoFMga0s+r1iH0R90ufjgNdkEi8D3SwrKTd7SxerHNUtvL0//yZceb2RV9NXVqBkYSWuVa1c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769503463; c=relaxed/simple; bh=3AqdWpRUEl/xO/ZdcVs+j44fpjbq0jkRoOeDvZLNh/0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mYCaZGhU7q2u/G8ziWZQ059h32VIiEgEZ6cmHBh+uHiBPGztrImO2eASyWglQ7/b8TENftrUv1TfLk7LX6PL4kXRtFAX4m82jCCu2Sk4JXc8KMpl5o+bIpWlcVMUKw7gbnaCbc7Vam9V4EQ+3KwjWp8vfpgmA8vgyDY6YfBVIEk= 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=jUOvrDMA; 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="jUOvrDMA" 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=3AqdWpRUEl/xO/ZdcVs+j44fpjbq0jkRoOeDvZLNh/0=; b=jUOvrDMA/ej/EIW9juhuedglQ6 aocX43HoZltsHNDeMhNPH2866OoEoLO0A1wc3qsd5KAOwkziCO3eTC2kVGocQOvRbfs/P5fqZDO2R c5AnDLxnOWmoMHAiI6R9xKpoWAju78IJa91uDVxJ3c6l5zlk/KPsD4tkeV1aBL9/c3z1u3m8iQNoF mJHTzfffdv4bcOvhRc2gzWHkvXP8LzpoNlJESqyCQ5GhKvHVxzjONbfxDirkyZCWSbsMyom3ZHoLt Y3fl8e1JrS7wXCOWdXZFQdCQ+foz4pnLdSPJp7ZnUnJhMPRUvDQesDN75Sq0qvJy7xBBjEibjxR0j lEKqItpw==; 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 1vkegG-00000007AWG-42wj; Tue, 27 Jan 2026 08:44:13 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 8120A300756; Tue, 27 Jan 2026 09:44:12 +0100 (CET) Date: Tue, 27 Jan 2026 09:44:12 +0100 From: Peter Zijlstra To: "Mohamed Abuelfotoh, Hazem" Cc: Mario Roy , Chris Mason , Joseph Salisbury , Adam Li , Josh Don , 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 Subject: Re: [PATCH 4/4] sched/fair: Proportional newidle balance Message-ID: <20260127084412.GV171111@noisy.programming.kicks-ass.net> References: <20251107160645.929564468@infradead.org> <20251107161739.770122091@infradead.org> <8760001e-0274-454c-a4e4-1f38a9695b88@gmail.com> <3ef2a178-db96-4a2c-9e74-44ba81bef030@amazon.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: <3ef2a178-db96-4a2c-9e74-44ba81bef030@amazon.com> On Sun, Jan 25, 2026 at 12:22:21PM +0000, Mohamed Abuelfotoh, Hazem wrote: > I can confirm that we are seeing a 4-11% performance regression in v6.12.66 > on multiple benchmarks running on c7a.4xlarge AWS EC2 instances that are > powered by AMD EPYC 9R14-series CPU (code-named Genoa) and c7i.4xlarge which > is powered by 4th-Generation Intel Xeon Scalable processor (code-named > Sapphire Rapids). For those not speaking Amazon; what actual system setup is that Xeon? Is that single socket or multi-socket? Going by the name, the 4x would suggest a quad-socket Xeon, which are somewhat beastly, but if I google this 'c7i.4xlarge' identifier, I get a puny single socket 16cpu thing. What is it?