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Message-ID: <20100531201424.GA6259@sgi.com> Date: Mon, 31 May 2010 15:14:24 -0500 From: Cliff Wickman <cpw@....com> To: JD <jd1008@...il.com> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH V3] x86, UV: BAU performance and error recovery On Fri, May 28, 2010 at 05:10:20PM -0700, JD wrote: > > > On 05/28/2010 04:36 PM, Cliff Wickman wrote: >> 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 >> > Would the similar filesystem you propose be backed by permanent storage, > unlike /proc? I withdraw my proposal for any new filesystem type, as debugfs works fine for what I'm talking about, as long as it is configured on by all the distributions. No, a permanent storage backed filesystem was not what I had in mind. -- Cliff Wickman SGI cpw@....com (651) 683-3824 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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