From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752047AbcL1VeZ (ORCPT <rfc822;w@1wt.eu>);
        Wed, 28 Dec 2016 16:34:25 -0500
Received: from mail-pg0-f49.google.com ([74.125.83.49]:36342 "EHLO
        mail-pg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751216AbcL1VeX (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 28 Dec 2016 16:34:23 -0500
Date: Wed, 28 Dec 2016 13:33:49 -0800 (PST)
From: David Rientjes <rientjes@google.com>
X-X-Sender: rientjes@chino.kir.corp.google.com
To: Michal Hocko <mhocko@kernel.org>
cc: Andrew Morton <akpm@linux-foundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [patch] mm, thp: always direct reclaim for MADV_HUGEPAGE even
 when deferred
In-Reply-To: <20161228084823.GB11470@dhcp22.suse.cz>
Message-ID: <alpine.DEB.2.10.1612281332320.13632@chino.kir.corp.google.com>
References: <20161222100009.GA6055@dhcp22.suse.cz> <alpine.DEB.2.10.1612221259100.29036@chino.kir.corp.google.com> <20161223085150.GA23109@dhcp22.suse.cz> <alpine.DEB.2.10.1612230154450.88514@chino.kir.corp.google.com> <20161223111817.GC23109@dhcp22.suse.cz>
 <alpine.DEB.2.10.1612231428030.88276@chino.kir.corp.google.com> <20161226090211.GA11455@dhcp22.suse.cz> <alpine.DEB.2.10.1612261639550.99744@chino.kir.corp.google.com> <20161227094008.GC1308@dhcp22.suse.cz> <alpine.DEB.2.10.1612271324300.67790@chino.kir.corp.google.com>
 <20161228084823.GB11470@dhcp22.suse.cz>
User-Agent: Alpine 2.10 (DEB 1266 2009-07-14)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, 28 Dec 2016, Michal Hocko wrote:

> I do care more about _users_ and their _experience_ than what
> application _writers_ think is the best. This is the whole point
> of giving the defrag tunable. madvise(MADV_HUGEPAGE) is just a hint to
> the system that using transparent hugepages is _preferable_, not
> mandatory. We have an option to allow stalls for those vmas to increase
> the allocation success rate. We also have tunable to completely ignore
> it. And we should also have an option to not stall.
> 

The application developer who uses madvise(MADV_HUGEPAGE) is doing so for 
a reason.

We lack the ability to defragment in the background for all users who 
don't want to block while allowing madvise(MADV_HUGEPAGE) users to block, 
as the changelog for this patch clearly indicates.

Thanks.