Messages in this thread | | | Date | Sun, 5 Feb 2006 21:51:52 -0800 | From | Paul Jackson <> | Subject | Re: [PATCH 2/5] cpuset memory spread page cache implementation and hooks |
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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 <pj@sgi.com> 1.925.600.0401 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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