Messages in this thread | | | Date | Tue, 02 Apr 2013 11:48:22 +0800 | From | Zhouping Liu <> | Subject | Re: THP: AnonHugePages in /proc/[pid]/smaps is correct or not? |
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On 04/02/2013 11:40 AM, Lin Feng wrote: > 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.
Feng, it's easy to understand now, thanks for your detailed explanation :)
Zhouping
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