From: Simon Kirby Subject: Re: VM issue causing high CPU loads Date: Thu, 3 Sep 2009 15:22:53 -0700 Message-ID: <20090903222253.GA8405@hostway.ca> References: <4A92A25A.4050608@yohan.staff.proxad.net> <20090824162155.ce323f08.akpm@linux-foundation.org> <4A96463E.5080002@corp.free.fr> <4A9C34F8.2010307@corp.free.fr> <20090902170642.f4381c1d.akpm@linux-foundation.org> <1251982884.18338.9.camel@heimdal.trondhjem.org> <4A9FC719.9020104@corp.free.fr> <1251986526.18338.29.camel@heimdal.trondhjem.org> <20090903200550.GB5257@hostway.ca> <1252010965.18338.63.camel@heimdal.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Yohan , Andrew Morton , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, Neil Brown , "J. Bruce Fields" , mikevs@xs4all.net To: Trond Myklebust Return-path: In-Reply-To: <1252010965.18338.63.camel@heimdal.trondhjem.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: On Thu, Sep 03, 2009 at 04:49:25PM -0400, Trond Myklebust wrote: > I'm working on increasing the idmapper scalability, however another > project is currently taking up most of my time. I can't guarantee that > the revised idmapper code will be finished in time to allow for > inclusion in 2.6.32. Sure, improving it would be nice for cases where it's needed, but in environments where all IDs are consistent (by design), it just seems silly to force this extra work for zero gain. > NFSv4 aspires to be an internet-wide protocol, and so you cannot use > uids/gids: they just aren't guaranteed to represent a unique user > outside your local LDAP/NIS or /etc/passwd domain. Furthermore, uids and > gids are a posix construct. They simply don't work in environments where > you may have lots of non-posix systems. So, for environments with all POSIX systems, what do you think about perhaps a mount or export flag that violates the spec on purpose to allow numeric IDs to be used? I can understand that the quiet use of IDs if name-to-user mapping fails will cause security issues in environments without consistent users, so it would now be unsafe to turn this on silently. However, making this an option seems reasonable to me. (Not that I know what I'm doing.) Simon-