Earlier Andrew wrote:
> Really has two forms, depending upon Kconfig.
>
> 1:
>
> static inline struct page *page_cache_alloc(struct address_space *x)
> {
> return alloc_pages(mapping_gfp_mask(x), 0);
> }
>
> That should be inlined.
>
> 2:
>
> static inline struct page *page_cache_alloc(struct address_space *x)
> {
> if (cpuset_mem_spread_check()) {
> int n = cpuset_mem_spread_node();
> return alloc_pages_node(n, mapping_gfp_mask(x), 0);
> }
> return alloc_pages(mapping_gfp_mask(x), 0);
> }
Later on, he wrote:
> I'm saying "gee, that looks big. Do you have time to investigate possible
> improvements?" They may come to naught.
After playing around with the variations we've considered on this
thread, the results are simple enough. I experimented with just
the 3 calls to page_cache_alloc_cold() in mm/filemap.c, because that
was easy, and all these calls have the same shape.
For non-NUMA, removing 'inline' from the three page_cache_alloc_cold()
calls in mm/filemap.c would cost a total of 16 bytes text size
For NUMA+CPUSET, removing it would _save_ 583 bytes total over the
three calls.
The "nm -S" size of the uninlined page_cache_alloc_cold() is 448 bytes
(it was 96 bytes before this cpuset patchset).
This is all on ia64 sn2_defconfig gcc 3.3.3.
The conclusion is straight forward, and as Andrew suspected.
We want these two page_cache_alloc*() routines out of line in the
NUMA case, but left inline for the non-NUMA case.
I will follow up with a simple patch that makes it easy to mark
routines that should be inline for UMA, out of line for NUMA.
These two page_cache_alloc*(), and perhaps also __cache_alloc() when
Pekka or I gets a handle on it, are candidates for this marking, as
routines to inline on UMA, out of line on NUMA.
--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <[email protected]> 1.925.600.0401
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