Raghavendra K T <raghavendra...@linux.vnet.ibm.com> writes:
> 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?. ) Hi. Just a concern. Will the performance reduce on some special storage backend? E.g. tape. The existent applications may using readahead for userspace I/O schedule to decrease seeking time. -- Thanks, Madper -- 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/
