Messages in this thread | | | Date | Wed, 11 Jun 2003 10:16:13 -0500 | From | Steven Pratt <> | Subject | Re: 2.5.70-mm2 causes performance drop of random read O_DIRECT |
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Nick Piggin wrote:
> Steven Pratt wrote: > >> Nick Piggin wrote: >> >>> Steven Pratt wrote: >>> >>>> Starting in 2.5.70-mm2 and continuing in the mm tree, there is a >>>> significant degrade in random read for block devices using >>>> O_DIRECT. The drop occurs for all block sizes and ranges from >>>> 30%-40. CPU usage is also lower although it may already be so low >>>> as to be irrelavent. >>> >>> Hi Steven, this is quite likely to be an io scheduler problem. >>> Is your test program rawread v2.1.5? >> >> This test was actually using 2.1.4, but the only difference in the >> 2.1.5 version is a fix for the test label array for the aio versions >> of the test. No functional change, just fixed the outputed test >> description. >> >>> What is the command line you are using to invoke the program? >> >> rawread -t6 -p8 -m1 -d2 -s4096 -n65536 -l1 -z -x >> >> Which you can find if you follow either results link and look in the >> benchmark directory where all raw benchmark out put is stored. > > OK thanks, I can now reproduce this! I'll work on it.
Looks like Andrew beat you to it. Both 2.5.70-mm7 and mm8 are back up to the previous performance levels for random reads.
Steve
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