Hi Zhouping, On 04/02/2013 11:09 AM, Zhouping Liu wrote: > I don't understand clearly the last sentence 'you'll probably only get 100% > hugepages only 1/512th of the time.' > could you please explain more details about 'only 1/512th of the time'?
IIUC, thp size is 2M so it may be comprised of 512 normal page(size 4k). Since your test code is not 2M aligned(not using posix_memalign()) so the start address of the mapped vma will be random, such as 2M*i+4k*1, 2M*i+4k*2...2M*i+k4*511, there is 512 possibilities. The only chance you get thp happens when the first map just starts at 2M*i, and the consequent maps also benefit from this. -------- snip -------- > > so, again, if I understand correctly, thp should tune the naturally aligned > maps, such as generated by mmap()/malloc(), > make such maps 'hugepagesize' aligned if the maps or vma is equal and greater > than 'hugepagesize', doesn't it? We may gain performance improving from this. thanks, linfeng -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
