From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f178.google.com (mail-pd0-f178.google.com [209.85.192.178]) by kanga.kvack.org (Postfix) with ESMTP id 27170828FD for ; Thu, 5 Feb 2015 06:45:05 -0500 (EST) Received: by pdjy10 with SMTP id y10so7320594pdj.7 for ; Thu, 05 Feb 2015 03:45:04 -0800 (PST) Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net. [150.101.137.141]) by mx.google.com with ESMTP id vx6si5806149pac.141.2015.02.05.03.45.02 for ; Thu, 05 Feb 2015 03:45:04 -0800 (PST) Date: Thu, 5 Feb 2015 22:45:00 +1100 From: Dave Chinner Subject: Re: [PATCH] gfs2: use __vmalloc GFP_NOFS for fs-related allocations. Message-ID: <20150205114459.GI12722@dastard> References: <1422849594-15677-1-git-send-email-green@linuxhacker.ru> <20150202053708.GG4251@dastard> <20150202081115.GI4251@dastard> <54CF51C5.5050801@redhat.com> <20150203223350.GP6282@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Oleg Drokin Cc: Steven Whitehouse , cluster-devel@redhat.com, Linux Kernel Mailing List , linux-mm@kvack.org On Wed, Feb 04, 2015 at 02:13:29AM -0500, Oleg Drokin wrote: > Hello! > > On Feb 3, 2015, at 5:33 PM, Dave Chinner wrote: > >> I also wonder if vmalloc is still very slow? That was the case some > >> time ago when I noticed a problem in directory access times in gfs2, > >> which made us change to use kmalloc with a vmalloc fallback in the > >> first place, > > Another of the "myths" about vmalloc. The speed and scalability of > > vmap/vmalloc is a long solved problem - Nick Piggin fixed the worst > > of those problems 5-6 years ago - see the rewrite from 2008 that > > started with commit db64fe0 ("mm: rewrite vmap layer").... > > This actually might be less true than one would hope. At least somewhat > recent studies by LLNL (https://jira.hpdd.intel.com/browse/LU-4008) > show that there's huge contention on vmlist_lock, so if you have vmalloc vmlist_lock and the list it protected went away in 3.10. Cheers, Dave. -- Dave Chinner david@fromorbit.com -- 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