Re: [patch 05/23] hugetlb: multi hstate proc files

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 28.05.2008 [22:44:39 -0700], Nishanth Aravamudan wrote:
> On 28.05.2008 [22:07:03 -0700], Nishanth Aravamudan wrote:
> > On 26.05.2008 [00:23:22 +1000], npiggin@suse.de wrote:
> > > Convert /proc output code over to report multiple hstates
> > > 
> > > I chose to just report the numbers in a row, in the hope 
> > > to minimze breakage of existing software. The "compat" page size
> > > is always the first number.
> > 
> > I'm assuming this is just copied from the old changelog, because as far
> > as I can tell, and from my quick testing just now with my sysfs patch,
> > hstates[0] is just whichever hugepage size is registered first. So that
> > either means by "compat" you meant the default on the current system
> > (which is only compatible with boots having the same order of boot-line
> > parameters) or we need to fix this patch to put HPAGE_SIZE (which we
> > haven't changed, per se) to be in hstates[0]. It might help to have a
> > helper macro called default_hstate (or a comment) [which I thought we
> > had in the beginnning of the patchset, but I see one of the intervening
> > patches removed it] indicating which state is the default when none is
> > specified.
> > 
> > The reason I bring this up is that I have my sysfs patchset in two
> > parts. First, I add the sysfs interface and then I remove the
> > multi-valued proc files. But for the latter, I rely on hstates[0] to be
> > the one we want to be presenting in proc. If that's not the case, how
> > should I be determining which hstate is the default? If that is the
> > case, shall I make the reverting patch also put the "right" value in
> > hstates[0]?
> 
> Oh, I think I know what is going on now. It's because I hadn't changed
> my test script between the old version of the stack and this one so it
> was still putting "hugepagesz=64k hugepagesz=16m hugepagesz=16g" on the
> kernel command-line, thus making 64k (the first hugepagesz specified) be
> the default for the system. So, actually, using hstates[0] in this way
> does work. Running one more test set without specifying any hugepagesz
> options on the kernel command-line to see the default layout in proc and
> sys is sane.

Confirmed that it's a result of my kernel command-line specifying 64k
first.

Thanks,
Nish

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center

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