From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753864Ab0E1XgP (ORCPT ); Fri, 28 May 2010 19:36:15 -0400 Received: from relay2.sgi.com ([192.48.179.30]:48513 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752631Ab0E1XgN (ORCPT ); Fri, 28 May 2010 19:36:13 -0400 Date: Fri, 28 May 2010 18:36:23 -0500 From: Cliff Wickman To: Greg KH Cc: "H. Peter Anvin" , linux-kernel@vger.kernel.org, mingo@elte.hu Subject: Re: [PATCH V3] x86, UV: BAU performance and error recovery Message-ID: <20100528233623.GA11356@sgi.com> References: <4BFFEFA1.1020307@zytor.com> <20100528164725.GA29208@suse.de> <20100528194334.GA7707@sgi.com> <20100528222321.GC25513@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100528222321.GC25513@suse.de> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 28, 2010 at 03:23:21PM -0700, Greg KH wrote: > On Fri, May 28, 2010 at 02:43:35PM -0500, Cliff Wickman wrote: > > > > On Fri, May 28, 2010 at 09:47:25AM -0700, Greg KH wrote: > > > On Fri, May 28, 2010 at 09:30:25AM -0700, H. Peter Anvin wrote: > > > > On 05/28/2010 06:33 AM, Cliff Wickman wrote: > > > > > - adds modification of tuning variables through /proc/sgi_uv > > > > > > > > Adding new directories in /proc for a proprietary architecture is > > > > frowned upon, to put it mildly. At the very least try to find a place > > > > in sysfs for it. > > > > > > > > [Cc: gregkh in order to find a place in sysfs] > > > > > > Hm, what type of files are you needing here? Do they corrispond with > > > any specific hardware devices? If so, just put them on the hardware > > > devices in sysfs. > > > > > > thanks, > > > > > > greg k-h > > > > There is an SGI-specific directory in sysfs: /sys/firmware/sgi_uv > > though the tuning variables for the handling of the hardware Broadcast > > Assist Unit don't fit there very logically. > > > > The BAU's statistics are already displayed through the UV-only > > /proc/sgi_uv/ptc_statistics. This was deemed necessary because of the > > potentially very large size of that file --- it is still true that a /sys file > > is limited to one page, is it not? > > It is limited to one single value, which would never be larger than a > page, so yes, it is limited to one page. > > What kind of information are you showing here? Should this thing just > be in debugfs instead? You can do whatever you want there. > > thanks, > > greg k-h /proc/sgi_uv/bau_tunables would be a read/write file to display and change nine threshold and delay values for tuning the BAU driver. I like debugfs, except that a distro may not build the kernel with it configured on. The tunables should be available as administrative options on a customer kernel, not just as a development tool. And in our case the distros are already building with other such writable options in /proc/sgi_uv. We'd like to postpone a wholesale move of such options (assuming there will be some better place) and stay with the existing location for this release. I know we (the community) would like to move non-process info out of /proc. It seems to me that we need a similar filesystem for large and/or administrative files. That's my perspective. -Cliff -- Cliff Wickman SGI cpw@sgi.com (651) 683-3824