Messages in this thread |  | | | Date | Mon, 11 Dec 2006 09:43:06 +0900 | | From | KAMEZAWA Hiroyuki <> | | Subject | Re: [RFC] [PATCH] virtual memmap on sparsemem v3 [0/4] introduction |
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On Sun, 10 Dec 2006 14:47:30 -0500 "Bob Picco" <bob.picco@hp.com> wrote: > > Intro: > > When using SPARSEMEM, pfn_to_page()/page_to_pfn() accesses global big table > > of mem_section. if SPARSEMEM_EXTREME, this is 2-level table lookup. > Did you gather any performance numbers comparing > VIRTUAL_MEM_MAP+SPARSEMEM to SPARSEMEM+EXTREME? I did some quick but > inconclusive (small machine) ones when you first posted. There was > perhaps a slight degradation in VIRTUAL_MEM_MAP+SPARSEMEM. > No, I didn't. I'll do when I have a chance to do it. I hope that this won't be merged until someone shows the benefit by data. (I think this verion is better than the first one but..)
IIRC, DISCONTIGMEM + VIRTUAL_MEM_MAP shows a bit better performance than SPARSEMEM_EXTREME. What I expect is to archive VIRTUAL_MEM_MAP performance with SPARSEMEM.
Now, we still have chance to optimization. - optimize pfn_valid. (I'll post this. mem_section[] will be never accessed in runtime by this.) - use large-sized-page (no concrete idea, maybe to modify map/unmap func will work enough.)
Thanks, -Kame
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