Re: SLUB tbench regression due to page allocator deficiency

[Paul Jackson <pj@sgi.com>]

Nick, listing things __alloc_pages() does:
> cpuset -- zone softwall stuff

That should be off the fast path.  So long as there is enough memory
(above watermarks on some node in current->mems_allowed) then there
should be no need to consider the cpuset softwall details.  Notice
that the first invocation of get_page_from_freelist() in __alloc_pages()
has the __GFP_HARDWALL included, bypassing the cpuset software code.

==

Is there someway to get profiling data from __alloc_pages() and
get_page_from_freelist(), for Christoph's test case.  I am imagining
publishing a listing of that code, with a column to the right
indicating how many times each line of code was executed, during the
interesting portion of running such a test case.

That would shine a bright light on any line(s) of code that get
executed way more often than seem necessary for such a load, and enable
the cast of dozens of us who have hacked this code at sometime to
notice opportunities for sucking less.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214

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