From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id B740A6B48FD for ; Tue, 27 Nov 2018 11:25:47 -0500 (EST) Received: by mail-ed1-f70.google.com with SMTP id m19so11066176edc.6 for ; Tue, 27 Nov 2018 08:25:47 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 34si2512774edu.226.2018.11.27.08.25.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Nov 2018 08:25:46 -0800 (PST) Date: Tue, 27 Nov 2018 17:25:44 +0100 From: Michal Hocko Subject: Re: [RFC PATCH 3/3] mm, proc: report PR_SET_THP_DISABLE in proc Message-ID: <20181127162544.GA6923@dhcp22.suse.cz> References: <20181120103515.25280-1-mhocko@kernel.org> <20181120103515.25280-4-mhocko@kernel.org> <0ACDD94B-75AD-4DD0-B2E3-32C0EDFBAA5E@oracle.com> <20181127131707.GW12455@dhcp22.suse.cz> <04647F77-FE93-4A8E-90C1-4245709B88A5@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <04647F77-FE93-4A8E-90C1-4245709B88A5@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: William Kucharski Cc: linux-api@vger.kernel.org, Andrew Morton , Alexey Dobriyan , linux-mm@kvack.org, LKML On Tue 27-11-18 07:50:08, William Kucharski wrote: > > > > On Nov 27, 2018, at 6:17 AM, Michal Hocko wrote: > > > > This is only about the process wide flag to disable THP. I do not see > > how this can be alighnement related. I suspect you wanted to ask in the > > smaps patch? > > No, answered below. > > > > >> I'm having to deal with both these issues in the text page THP > >> prototype I've been working on for some time now. > > > > Could you be more specific about the issue and how the alignment comes > > into the game? The only thing I can think of is to not report VMAs > > smaller than the THP as eligible. Is this what you are looking for? > > Basically, if the faulting VA is one that cannot be mapped with a THP > due to alignment or size constraints, it may be "eligible" for THP > mapping but ultimately can't be. > > I was just double checking that this was meant to be more of a check done > before code elsewhere performs additional checks and does the actual THP > mapping, not an all-encompassing go/no go check for THP mapping. I am still not sure I follow you completely here. This just reports per-task eligibility. The system wide eligibility is reported via sysfs and the per vma eligibility is reported via /proc//smaps. -- Michal Hocko SUSE Labs