Re: [PATCH 2/5] cpuset memory spread page cache implementation and hooks

[Paul Jackson <pj@sgi.com>]

Andrew, responding to pj:
> >   static inline struct page *page_cache_alloc_cold(struct address_space *x)
> >   {
> >  +	if (cpuset_mem_spread_check()) {
> >  +		int n = cpuset_mem_spread_node();
> >  +		return alloc_pages_node(n, mapping_gfp_mask(x)|__GFP_COLD, 0);
> >  +	}
> >   	return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
> >   }
> 
> This is starting to get a bit bloaty.  Might be worth thinking about
> uninlining these for certain Kconfig combinations.

Good point.

I can easily imagine doing something like the following, to move some
of the logic out of line, rather in the same manner as I did the slab
cache hooks, in "[PATCH 4/5] cpuset memory spread slab cache
optimizations"

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
static struct page *page_cache_alloc_mem_spread_cold(struct address_space *x)
{
	int n = cpuset_mem_spread_node();
	return alloc_pages_node(n, mapping_gfp_mask(x)|__GFP_COLD, 0);
}

static inline struct page *page_cache_alloc_cold(struct address_space *x)
{
	if (cpuset_mem_spread_check())
		return page_cache_alloc_mem_spread_cold(x);
	return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
}
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

But I am not sure what you mean by "uninline for certain Kconfig
combinations."  Do you mean uninline these two page_cache_alloc*()
routines, for all configs that enable CONFIG_CPUSET?

    The configs w/o CONFIG_CPUSET have "cpuset_mem_spread_check()"
    defined as a constant 0, so for them, this bloat will disappear,
    so they would not gain any bloat reduction by uninlining these
    page_cache_alloc*() routines, in any case.

    The configs with CONFIG_CPUSET might include future major
    desktop PC distros, which might not want these page_cache_alloc*()
    routines uninlined (though I am sure they would like them to be
    non-bloaty.)

Tell me more.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.925.600.0401
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