From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot0-f200.google.com (mail-ot0-f200.google.com [74.125.82.200]) by kanga.kvack.org (Postfix) with ESMTP id B81566B000A for ; Fri, 16 Feb 2018 12:30:23 -0500 (EST) Received: by mail-ot0-f200.google.com with SMTP id i5so1967736otf.8 for ; Fri, 16 Feb 2018 09:30:23 -0800 (PST) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id t200si787763oih.27.2018.02.16.09.30.22 for ; Fri, 16 Feb 2018 09:30:22 -0800 (PST) From: Punit Agrawal Subject: Re: [bug?] mallocstress poor performance with THP on arm64 system References: <1523287676.1950020.1518648233654.JavaMail.zimbra@redhat.com> <1847959563.1954032.1518649501357.JavaMail.zimbra@redhat.com> <20180215090246.qrsnncq3ajtbdlfy@node.shutemov.name> Date: Fri, 16 Feb 2018 17:30:19 +0000 In-Reply-To: <20180215090246.qrsnncq3ajtbdlfy@node.shutemov.name> (Kirill A. Shutemov's message of "Thu, 15 Feb 2018 12:02:46 +0300") Message-ID: <87a7w84zbo.fsf@e105922-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Jan Stancek , linux-mm@kvack.org, lwoodman , Rafael Aquini , Andrea Arcangeli Hi Kirill, "Kirill A. Shutemov" writes: > On Wed, Feb 14, 2018 at 06:05:01PM -0500, Jan Stancek wrote: >> Hi, >> >> mallocstress[1] LTP testcase takes ~5+ minutes to complete >> on some arm64 systems (e.g. 4 node, 64 CPU, 256GB RAM): >> real 7m58.089s >> user 0m0.513s >> sys 24m27.041s >> >> But if I turn off THP ("transparent_hugepage=never") it's a lot faster: >> real 0m4.185s >> user 0m0.298s >> sys 0m13.954s >> > > It's multi-threaded workload. My *guess* is that poor performance is due > to lack of ARCH_ENABLE_SPLIT_PMD_PTLOCK support on arm64. In this instance I think the latency is due to the large size of PMD hugepages and THP=always. But split PMD locks seem like a useful feature to have for large core count systems. I'll have a go at enabling this for arm64. Thanks, Punit -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org