From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="gS+2sAKa" Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5AA25A0; Tue, 28 Nov 2023 05:22:34 -0800 (PST) Received: by mail-pl1-x62c.google.com with SMTP id d9443c01a7336-1cfc34b6890so19769405ad.1; Tue, 28 Nov 2023 05:22:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701177754; x=1701782554; darn=vger.kernel.org; h=content-transfer-encoding:subject:from:cc:to:content-language :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=30VypmY2CFZ8lvqagGC6jaet2OpETydP+u6D3TSu8fI=; b=gS+2sAKa2JBYPVICquPPt+xxjHgT5NonnAOR9Cqy8i7FTINvDQVAf/A0/FGQgetPCV AUN0lka06G7EFwylo9Mg/Nllkm9BmB6SB7coVFP/fXq1Mgmg3CyhFS3hDmx6BPgZkLTk Wto9aTndWnNpv9uAFjhsqvj6+p3PFabmTqwsaZkTAlx+66FRZal1lwVNZBqZJnEJPvsz 64mnZpQYzEMsLcwwioi8z4o+IoY+VZr/lRwuOKmpBsL6fVoHVbLg5WJW8/3pDXVQoBNa 1+6zjBO/TxGrtwoT9RYlhJA4a1C6rrzR9knhZ9JzkLIJ9mLHdife8X7V/c1Eabx2mky1 lDXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701177754; x=1701782554; h=content-transfer-encoding:subject:from:cc:to:content-language :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=30VypmY2CFZ8lvqagGC6jaet2OpETydP+u6D3TSu8fI=; b=esnAz3IWr4MPwVkAk2tfURXRFB/EDbvo4uNK7q0Lenk4NBNGE5nliOpf+glX9qCF3o TzwGlNFEdAOz5UMTwJJ54zsZBPWG7WVnfnW/vw9/SZgOMD6aYwKuhMltjsCXIUmXadER sURfYzffcaMPM4CVZOfcy+rXV93F7/JHXGYfuiOFv+6mcS0iYh/3H7SwZAHblDSkOCVh iStQbsuIIXmokrv+Xnqj0rwSCU281fEkRk6d8a3aQgni7eSVt3xwISFgJp8QopMY8bcP lEGfUgQv7iSiGPkbCTNX2rT8Aoaz+GJj4+7yhTQoBd4fFyD+8mQi+SkTt4T74BWIudnk 6rNA== X-Gm-Message-State: AOJu0YwK8iNoxLWw7wf00JspSo9K76MbgW4qrwmaIJW766yi0DQkAY/y mHBmivqMnXDNAVOPjHUYrNMJtcdIK6qIAA== X-Google-Smtp-Source: AGHT+IH3JFeDBdC18l8j/Q+NB48Ja1KZVkzEIv229wi7jf8qWZFdPd/OFYbLqFjShGbgQBekqvZ+4w== X-Received: by 2002:a17:902:ead2:b0:1cf:a53f:200f with SMTP id p18-20020a170902ead200b001cfa53f200fmr16674842pld.32.1701177753559; Tue, 28 Nov 2023 05:22:33 -0800 (PST) Received: from [192.168.0.106] ([103.131.18.64]) by smtp.gmail.com with ESMTPSA id u11-20020a170902e5cb00b001cfbd011ca9sm5767276plf.113.2023.11.28.05.22.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Nov 2023 05:22:33 -0800 (PST) Message-ID: <01df8329-06d7-4fd1-9c7a-05296f33231e@gmail.com> Date: Tue, 28 Nov 2023 20:22:27 +0700 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: Linux Kernel Mailing List , Linux Regressions , Linux Power Management Cc: "Rafael J. Wysocki" , Viresh Kumar , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Ramses VdP From: Bagas Sanjaya Subject: Fwd: Intel hybrid CPU scheduler always prefers E cores Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, I come across an interesting bug report on Bugzilla [1]. The reporter wrote: > I am running an intel alder lake system (Core i7-1260P), with a mix of P and E cores. > > Since Linux 6.6, and also on the current 6.7 RC, the scheduler seems to have a strong preference for the E cores, and single threaded workloads are consistently scheduled on one of the E cores. > > With Linux 6.4 and before, when I ran a single threaded CPU-bound process, it was scheduled on a P core. With 6.5, it seems that the choice of P or E seemed rather random. > > I tested these by running "stress" with different amounts of threads. With a single thread on Linux 6.6 and 6.7, I always have an E core at 100% and no load on the P cores. Starting from 3 threads I get some load on the P cores as well, but the E cores stay more heavily loaded. > With "taskset" I can force a process to run on a P core, but clearly it's not very practical to have to do CPU scheduling manually. > > This severely affects single-threaded performance of my CPU since the E cores are considerably slower. Several of my workflows are now a lot slower due to them being single-threaded and heavily CPU-bound and being scheduled on E cores whereas they would run on P cores before. > > I am not sure what the exact desired behaviour is here, to balance power consumption and performance, but currently my P cores are barely used for single-threaded workloads. > > Is this intended behaviour or is this indeed a regression? Or is there perhaps any configuration that I should have done from my side? Is there any further info that I can provide to help you figure out what's going on? PM and scheduler people, is this a regression or works as intended? Thanks. [1]: https://bugzilla.kernel.org/show_bug.cgi?id=218195 -- An old man doll... just what I always wanted! - Clara