Messages in this thread | | | Date | Wed, 22 Jun 2011 10:41:54 +0800 | From | Cong Wang <> | Subject | Re: [PATCH 2/3] mm: make the threshold of enabling THP configurable |
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于 2011年06月21日 17:36, Mel Gorman 写道: > > Fragmentation avoidance benefits from tuning min_free_kbytes to a higher > value and minimising fragmentation-related problems is crucial if THP is > to allocate its necessary pages. > > THP tunes min_free_kbytes automatically and this value is in part > related to the number of zones. At 512M on a single node machine, the > recommended min_free_kbytes is close to 10% of memory which is barely > tolerable as it is. At 256M, it's 17%, at 128M, it's 34% so tuning the > value lower has diminishing returns as the performance impact of giving > up such a high percentage of free memory is not going to be offset by > reduced TLB misses. Tuning it to a higher value might make some sense > if the higher min_free_kbytes was a problem but it would be much more > rational to tune it as a sysctl than making it a compile-time decision. >
What this patch changed is the check of total memory pages in hugepage_init(), which I don't think is suitable as a sysctl.
If you mean min_free_kbytes could be tuned as a sysctl, that should be done in other patch, right? :)
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