* Why does journal mode outperforms all other modes when reading and writing data at the same time? @ 2013-05-28 14:39 jingguo yao 2013-05-28 16:14 ` Jan Kara 0 siblings, 1 reply; 2+ messages in thread From: jingguo yao @ 2013-05-28 14:39 UTC (permalink / raw) To: linux-ext4 Documentation/filesystems/ext4.txt has the following sentence: This mode is the slowest except when data needs to be read from and written to disk at the same time where it outperforms all others modes. And the following link talks about it in more details. Can anybody give the reason? http://www.ibm.com/developerworks/library/l-fs8/index.html#4 -- Jingguo ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Why does journal mode outperforms all other modes when reading and writing data at the same time? 2013-05-28 14:39 Why does journal mode outperforms all other modes when reading and writing data at the same time? jingguo yao @ 2013-05-28 16:14 ` Jan Kara 0 siblings, 0 replies; 2+ messages in thread From: Jan Kara @ 2013-05-28 16:14 UTC (permalink / raw) To: jingguo yao; +Cc: linux-ext4 On Tue 28-05-13 22:39:18, jingguo yao wrote: > Documentation/filesystems/ext4.txt has the following sentence: > > This mode is the slowest except when data needs to be read from and > written to disk at the same time where it outperforms all others > modes. > > And the following link talks about it in more details. Can anybody give > the reason? > > http://www.ibm.com/developerworks/library/l-fs8/index.html#4 Not sure why exactly data=journal was faster in that workload. But generally data=journal is known to help if you have shortlived files which are then written only to the journal and deleted before they are copied to the final location on disk. Also it may help by penalizing the writer so that readers have better chance to do their work... Honza -- Jan Kara <jack@suse.cz> SUSE Labs, CR ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2013-05-28 16:14 UTC | newest] Thread overview: 2+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2013-05-28 14:39 Why does journal mode outperforms all other modes when reading and writing data at the same time? jingguo yao 2013-05-28 16:14 ` Jan Kara
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