Messages in this thread | | | Date | Sun, 8 Jul 2012 15:53:35 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH] mm: don't invoke __alloc_pages_direct_compact when order 0 |
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On Sun, 8 Jul 2012, JoonSoo Kim wrote:
> >> __alloc_pages_direct_compact has many arguments so invoking it is very costly. > >> And in almost invoking case, order is 0, so return immediately. > >> > > > > If "zero cost" is "very costly", then this might make sense. > > > > __alloc_pages_direct_compact() is inlined by gcc. > > In my kernel image, __alloc_pages_direct_compact() is not inlined by gcc.
Adding Andrew and Mel to the thread since this would require that we revert 11e33f6a55ed ("page allocator: break up the allocator entry point into fast and slow paths") which would obviously not be a clean revert since there have been several changes to these functions over the past three years.
I'm stunned (and skeptical) that __alloc_pages_direct_compact() is not inlined by your gcc, especially since the kernel must be compiled with optimization (either -O1 or -O2 which causes these functions to be inlined). What version of gcc are you using and on what architecture? Please do "make mm/page_alloc.s" and send it to me privately, I'll file this and fix it up on gcc-bugs.
I'll definitely be following up on this.
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