* Why all raid devices do have zero 'time in queue' value? @ 2012-03-10 22:33 George Shuklin 2012-03-11 2:10 ` NeilBrown 0 siblings, 1 reply; 2+ messages in thread From: George Shuklin @ 2012-03-10 22:33 UTC (permalink / raw) To: dm-devel Good day. I've look to stat for all MD devices I have (raid0, raid1, raid10) - all of them reports 0 for time_in_queue field in /sys/block/mdX/stat file. Is any reason why all raid devices contains no information about time spent on requests processing? Thanks. ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Why all raid devices do have zero 'time in queue' value? 2012-03-10 22:33 Why all raid devices do have zero 'time in queue' value? George Shuklin @ 2012-03-11 2:10 ` NeilBrown 0 siblings, 0 replies; 2+ messages in thread From: NeilBrown @ 2012-03-11 2:10 UTC (permalink / raw) To: device-mapper development; +Cc: george.shuklin [-- Attachment #1.1: Type: text/plain, Size: 812 bytes --] On Sun, 11 Mar 2012 02:33:34 +0400 George Shuklin <george.shuklin@gmail.com> wrote: > Good day. > > I've look to stat for all MD devices I have (raid0, raid1, raid10) - all > of them reports 0 for time_in_queue field in /sys/block/mdX/stat file. > > Is any reason why all raid devices contains no information about time > spent on requests processing? > Wrong mailing list for MD - you want linux-raid@vger.kernel.org But I can still answer : These raid levels don't queue requests at all. They just pass them straight to the relevant underlying devices. (Now admittedly RAID5 does queue requests but doesn't set the time_in_queue field, but that is a separate issue). If you really care about time_in_queue, you need to look at the queues of the member devices. NeilBrown [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 828 bytes --] [-- Attachment #2: Type: text/plain, Size: 0 bytes --] ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2012-03-11 2:10 UTC | newest] Thread overview: 2+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2012-03-10 22:33 Why all raid devices do have zero 'time in queue' value? George Shuklin 2012-03-11 2:10 ` NeilBrown
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