From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Serge E. Hallyn" Subject: Re: [PATCH] user_ns: Improve the user_ns on-the-slab packaging Date: Tue, 7 Dec 2010 08:50:43 -0600 Message-ID: <20101207145043.GD4674@hallyn.com> References: <4CFE40D1.5000309@parallels.com> <20101207142747.GB4674@hallyn.com> <4CFE45A0.8070408@parallels.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4CFE45A0.8070408@parallels.com> Sender: linux-kernel-owner@vger.kernel.org To: Pavel Emelyanov Cc: "Serge E. Hallyn" , Andrew Morton , Linux Containers , Linux Kernel Mailing List List-Id: containers.vger.kernel.org Quoting Pavel Emelyanov (xemul@parallels.com): > On 12/07/2010 05:27 PM, Serge E. Hallyn wrote: > > Quoting Pavel Emelyanov (xemul@parallels.com): > >> Currently on 64-bit arch the user_namespace is 2096 and when > >> being kmalloc-ed it resides on a 4k slab wasting 2003 bytes. > >> > >> If we allocate a separate cache for it and reduce the hash size > >> from 128 to 64 chains the packaging becomes *much* better - the > > > > Hey Pavel, > > > > I trust you've done some performance tests and found no > > regressions with a few hundred users? > > How many hundreds are you interested in? :) 128 users didn't > reveal any regressions. I have no good guess, would have said 500, 128 sounds good :) So long as actual benchmarks showed no regression within a 95% confidence interval. Thanks for the patch, the memory savings are impressive. Acked-by: Serge E. Hallyn -serge PS - I'm hoping to send out a version of the targeted capabilities (based on userns) patchset later this week.