From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lj1-f179.google.com (mail-lj1-f179.google.com [209.85.208.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 414EC181323 for ; Wed, 17 Jul 2024 16:34:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721234048; cv=none; b=Zy5P/leZv7uEORfQp0Jlbs9Pk9WtvHWH8xHj2yMxtgY147igaNIewxk1djnOM6Ow1YqZNWykgoDvN7W/xtbr+OB8XiFiH5TE43RPvkR7x4uRe0hNUwdMg2EgfDdLzlqQ2ZCtcaOagjpeoToR7VBses7jrT6stEr4FEGxy2TV/eg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721234048; c=relaxed/simple; bh=32qbVbdcIIo082PD1NEo17pI9Fe6+jCMt4sWhJ+oEKQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FhS55RddeoiyjPZYXj5hHpbqWnHQDUYrDqw2JcWged0Ah999fmryzk64AjgPMSFFbFTKxM3j95Fp7FO1rNY84dXbZfi3D7Muh/yj1B5e6SVZxYhAD3N2sbl841GfbOuHmWc3nMGmfkFh1S6Umh64NtXyr4uQB9I0F4ECTkIqSkY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=FQP7pP3O; arc=none smtp.client-ip=209.85.208.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FQP7pP3O" Received: by mail-lj1-f179.google.com with SMTP id 38308e7fff4ca-2ee92e3a4efso7113001fa.0 for ; Wed, 17 Jul 2024 09:34:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1721234045; x=1721838845; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=32qbVbdcIIo082PD1NEo17pI9Fe6+jCMt4sWhJ+oEKQ=; b=FQP7pP3OcggaoG2xiUoGcFqJBz8a7b5m0aKCGwBIF0roXtiGnqcsryhbdlRB6NUE2V 8wPfD4TncvSxyv7kgntewS5OFhUd0SiTTsw0s86oNcMXpae5NaJ5FYPFgMVxynNZEFLm MAM+iB9tZWNy7P17VuAi6kECyrb+KOCnDqbZDfx0NffOWMV7DKofG+P0+MFOoOhyrIXh dzEtZjYmbg9lXJQdJR6aA4QFYLLsJlzfeYGqBOwcVvWbol/RiXytzMthtRciF7L6W9IR SwMOresse0OYD/kZoE+2LnvrGyoagP8TtSqS2fai288d6t+JJ4y50YjlNhwRuhAlIU1M dlqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1721234045; x=1721838845; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=32qbVbdcIIo082PD1NEo17pI9Fe6+jCMt4sWhJ+oEKQ=; b=vLxiqDUTTQDczEcGBcDe7G62X8AS3fReAfjl3SjCtFVB47qQS5ZTEKOCWeoDwU9HDf FYWVrfkBVLgxv2L9vnPB6LfYkhBr+rOt1K6VXAltlminKlH7YuxB3SI2zUZIZACpxRIi RtYIeb4VaGusdwu9utyO6rbMBO+o/WTUq8mRY0LL3CZCEDiayVWkDmtoK6F3FTqWGmIf 5TcfRO2udYYpKqX/Fg9kkr6xm8r84nMF8lHMhHcw3hnJFB7L46ftmw5H0JbHLExl05jK R5VwsJew6Yzcb7TNjj3kiaMdY5vcc6gu2GpKrxMBnvHDiVr3axMjdHZ9LXqie0s6htD7 mFCw== X-Forwarded-Encrypted: i=1; AJvYcCXbN/Xk/PCaXzObAlRb1bLRUyqEzlv4bvQ6nRU5f9jTApu5vNywVT8aE5XqLZcxO88oGDK1jaQdO20yZXgzC+xN1nXazHet4HatKsLt X-Gm-Message-State: AOJu0YxZjwuHDseTiPsTdTOXgrnkhLFq5mMn/P452Byx0ERxRQJa8ryE 78qs4tfYQZZRyUEO+aFqQ3F/JVZw2hkPNr81rjAKPzJeq5S+gzk6 X-Google-Smtp-Source: AGHT+IFHoEqW03F6S4z6swFivCqKl+77KnSoWGbGJ5TX/ZETCILoAnLRjscrZ9ghdPSFooND/k9L8g== X-Received: by 2002:a2e:be24:0:b0:2ef:81:aa5 with SMTP id 38308e7fff4ca-2ef00810afdmr9009701fa.8.1721234045118; Wed, 17 Jul 2024 09:34:05 -0700 (PDT) Received: from ed.ac.uk ([2001:630:3c1:90:1614:6de0:61c7:40b0]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-427c77a5804sm3671585e9.16.2024.07.17.09.34.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jul 2024 09:34:04 -0700 (PDT) Date: Wed, 17 Jul 2024 17:34:03 +0100 From: Karim Manaouil To: Vlastimil Babka Cc: Bharata B Rao , linux-mm@kvack.org, linux-kernel@vger.kernel.org, nikunj@amd.com, "Upadhyay, Neeraj" , Andrew Morton , David Hildenbrand , willy@infradead.org, yuzhao@google.com, kinseyho@google.com, Mel Gorman , Mateusz Guzik Subject: Re: Hard and soft lockups with FIO and LTP runs on a large system Message-ID: References: <3128c3c0-ede2-4930-a841-a1da56e797d7@suse.cz> 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: <3128c3c0-ede2-4930-a841-a1da56e797d7@suse.cz> On Wed, Jul 17, 2024 at 11:42:31AM +0200, Vlastimil Babka wrote: > Seems to me it could be (except that ZONE_DMA corner case) a general > scalability issue in that you tweak some part of the kernel and the > contention moves elsewhere. At least in MM we have per-node locks so this > means 256 CPUs per lock? It used to be that there were not that many > (cores/threads) per a physical CPU and its NUMA node, so many cpus would > mean also more NUMA nodes where the locks contention would distribute among > them. I think you could try fakenuma to create these nodes artificially and > see if it helps for the MM part. But if the contention moves to e.g. an > inode lock, I'm not sure what to do about that then. AMD EPYC BIOSes have an option called NPS (Nodes Per Socket) that can be set to 1, 2, 4 or 8 and that divides the system up into the chosen number of NUMA nodes. Karim PhD Student Edinburgh University