Return-Path: Received: from smtp-out.google.com ([216.239.44.51]:21132 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755629Ab0EXJ5f (ORCPT ); Mon, 24 May 2010 05:57:35 -0400 Received: from hpaq6.eem.corp.google.com (hpaq6.eem.corp.google.com [172.25.149.6]) by smtp-out.google.com with ESMTP id o4O9vWY2017930 for ; Mon, 24 May 2010 02:57:33 -0700 Received: from vws3 (vws3.prod.google.com [10.241.21.131]) by hpaq6.eem.corp.google.com with ESMTP id o4O9vLGc014350 for ; Mon, 24 May 2010 02:57:31 -0700 Received: by vws3 with SMTP id 3so249713vws.28 for ; Mon, 24 May 2010 02:57:31 -0700 (PDT) In-Reply-To: References: Date: Mon, 24 May 2010 02:57:30 -0700 Message-ID: Subject: Re: TMPFS over NFSv4 From: Hugh Dickins To: Tharindu Rukshan Bamunuarachchi Cc: linux-mm@kvack.org, linux-nfs@vger.kernel.org, Alan Cox Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Mon, May 24, 2010 at 2:26 AM, Tharindu Rukshan Bamunuarachchi wrote: > thankx a lot Hugh ... I will try this out ... (bit harder patch > already patched SLES kernel :-p ) .... If patch conflicts are a problem, you really only need to put in the two-liner patch to mm/mmap.c: Alan was seeking perfection in the rest of the patch, but you can get away without it. > > BTW, what does Alan means by "strict overcommit" ? Ah, that phrase, yes, it's a nonsense, but many of us do say it by mistake. Alan meant to say "strict no-overcommit". > > e.g. > i did not see this issues with "0 > /proc/sys/vm/overcommit_accounting" I assume "overcommit_accounting" is either a typo for "overcommit_memory", or SLES gives "overcommit_memory" a slightly different name. 0 means overcommit memory (let people allocate more private writable user memory than there is actually ram+swap to back), but throw in a check against really wild allocation requests. 1 omits even that check. > But this happened several times with "2 > /proc/sys/vm/overcommit_accounting" 2 means account for all private writable memory and fail any allocation which would take the system over the edge - the edge being defined roughly by overcommit_ratio * (ram+swap) (I expect there's a divisor needed in there!) i.e. 2 means strict no-overcommit. So what you see fits with what Alan was fixing. Hugh