From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com (mail-pa0-f47.google.com [209.85.220.47]) by kanga.kvack.org (Postfix) with ESMTP id EF1986B0253 for ; Mon, 24 Aug 2015 16:20:08 -0400 (EDT) Received: by padfo6 with SMTP id fo6so1053231pad.3 for ; Mon, 24 Aug 2015 13:20:08 -0700 (PDT) Received: from na01-bn1-obe.outbound.protection.outlook.com (mail-bn1bbn0109.outbound.protection.outlook.com. [157.56.111.109]) by mx.google.com with ESMTPS id gw7si29261634pac.35.2015.08.24.13.20.07 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 24 Aug 2015 13:20:08 -0700 (PDT) From: "Bridgman, John" Subject: Re: Can we disable transparent hugepages for lack of a legitimate use case please? Date: Mon, 24 Aug 2015 20:20:01 +0000 Message-ID: <20150824201952.5931089.66204.70511@amd.com> References: In-Reply-To: Content-Language: en-US Content-Type: multipart/alternative; boundary="_000_2015082420195259310896620470511amdcom_" MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: James Hartshorn , "linux-mm@kvack.org" --_000_2015082420195259310896620470511amdcom_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable We find it useful for GPU compute applications (APU I suppose, with GPU acc= ess via IOMMUv2) working on large datasets. I wouldn't have expected THP to find much use for databases -- those seem t= o be more like graphics stacks where you have enough hints about future usa= ge to justify explicit management of pages. I thought of THP as "the soluti= on for everything else". From: James Hartshorn Sent: Monday, August 24, 2015 3:12 PM To: linux-mm@kvack.org Subject: Can we disable transparent hugepages for lack of a legitimate use = case please? Hi, I've been struggling with transparent hugepage performance issues, and can'= t seem to find anyone who actually uses it intentionally. Virtually every = database that runs on linux however recommends disabling it or setting it t= o madvise. I'm referring to: /sys/kernel/mm/transparent_hugepage/enabled I asked on the internet http://unix.stackexchange.com/questions/201906/does= -anyone-actually-use-and-benefit-from-transparent-huge-pages and got no res= ponses there. Independently I noticed "sysctl: The scan_unevictable_pages sysctl/node-interface has been disabled= for lack of a legitimate use case. If you have one, please send an email = to linux-mm@kvack.org." And thought wow that's exactly what should be done to transparent hugepages= . Thoughts? --_000_2015082420195259310896620470511amdcom_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

From: James Hartshorn

Sent: Monday, August 24, 2015 3:12 PM

To: linux-mm@kvack.org

Subject: Can we disable transparent hugepages for lack of a leg= itimate use case please?

Hi,

I've been struggling with transparent hugepage performance issues, and c= an't seem to find anyone who actually uses it intentionally. Virtuall= y every database that runs on linux however recommends disabling it or sett= ing it to madvise. I'm referring to:

/sys/kernel/mm/transparent_hugepage/enabled

I asked on the internet http://unix.stackexchange.com/que= stions/201906/does-anyone-actually-use-and-benefit-from-transparent-huge-pa= ges and got no responses there.

Independently I noticed

"sysctl: The scan_unevictable_pages sysctl/node-interface has been = disabled for lack of a legitimate use case. If you have one, please s= end an email to linux-mm@kvack.org."

And thought wow that's exactly what should be done to transparent hugepa= ges.

Thoughts?

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