From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964783AbWG3XBr (ORCPT ); Sun, 30 Jul 2006 19:01:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964784AbWG3XBr (ORCPT ); Sun, 30 Jul 2006 19:01:47 -0400 Received: from ms-smtp-01.nyroc.rr.com ([24.24.2.55]:49599 "EHLO ms-smtp-01.nyroc.rr.com") by vger.kernel.org with ESMTP id S964783AbWG3XBr (ORCPT ); Sun, 30 Jul 2006 19:01:47 -0400 Subject: Re: 2.6.18-rc2-mm1 timer int 0 doesn't work From: Steven Rostedt To: Ingo Molnar Cc: Andrew Morton , Paul Fulghum , ak@muc.de, linux-kernel@vger.kernel.org, ebiederm@xmission.com In-Reply-To: <20060729040337.GB29875@elte.hu> References: <20060727015639.9c89db57.akpm@osdl.org> <1154112276.3530.3.camel@amdx2.microgate.com> <20060728144854.44c4f557.akpm@osdl.org> <20060728233851.GA35643@muc.de> <1154132126.3349.8.camel@localhost.localdomain> <1154135792.2557.7.camel@localhost.localdomain> <20060728182450.8f5cbf76.akpm@osdl.org> <20060729040337.GB29875@elte.hu> Content-Type: text/plain Date: Sun, 30 Jul 2006 19:00:57 -0400 Message-Id: <1154300457.10074.40.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2006-07-29 at 06:03 +0200, Ingo Molnar wrote: > * Andrew Morton wrote: > > > > 2.6.18-rc2 works fine with same config. > > > > > > In this case the error is: > > > > > > No per-cpu room for modules > > > > yeah, sorry, that's a known problem which nobody appears to be doing > > anything about. The expansion of NR_IRQS gobbles all the percpu > > memory in the kstat structure. > > while the fundamental issue is the NR_IRQS problem which we'll fix > separately, Steve has a patchset to make percpu room dynamic: > > http://lkml.org/lkml/2006/4/14/137 That implementation was doomed because it added another dereference that would kill numa implementations. I implemented another version that used page tables, but some people said that this would waste TLB entries. See here http://lwn.net/Articles/184103/ Perhaps another version that might be beneficial is one that mixes the current approach with this one. That is to have a dynamic page case that would happen only after a default was exhausted. And then we could even warn about it if we don't like that. This way we can warn the user if they don't like having the module's per_cpu files dynamically allocated, which might slow down the system do to another TLB line taken. -- Steve