Messages in this thread | | | Date | Tue, 18 Feb 2014 17:34:54 +0530 | From | Raghavendra K T <> | Subject | Re: [PATCH V6 ] mm readahead: Fix readahead fail for memoryless cpu and limit readahead pages |
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On 02/18/2014 03:19 PM, Jan Kara wrote: > On Tue 18-02-14 12:55:38, Raghavendra K T wrote: >> Currently max_sane_readahead() returns zero on the cpu having no local memory node >> which leads to readahead failure. Fix the readahead failure by returning >> minimum of (requested pages, 512). Users running application on a memory-less cpu >> which needs readahead such as streaming application see considerable boost in the >> performance. >> >> Result: >> fadvise experiment with FADV_WILLNEED on a PPC machine having memoryless CPU >> with 1GB testfile ( 12 iterations) yielded around 46.66% improvement. >> >> fadvise experiment with FADV_WILLNEED on a x240 machine with 1GB testfile >> 32GB* 4G RAM numa machine ( 12 iterations) showed no impact on the normal >> NUMA cases w/ patch. > Can you try one more thing please? Compare startup time of some big > executable (Firefox or LibreOffice come to my mind) for the patched and > normal kernel on a machine which wasn't hit by this NUMA issue. And don't > forget to do "echo 3 >/proc/sys/vm/drop_caches" before each test to flush > the caches. If this doesn't show significant differences, I'm OK with the > patch. >
Thanks Honza, I checked with firefox (starting to particular point).. I do not see any difference. Both the case took around 14sec.
( some time it is even faster.. may be because we do not do free page calculation?. )
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