Messages in this thread | | | From | Bill Davidsen <> | Subject | Re: 2.6.4 : 100% CPU use on EIDE disk operarion, VIA chipset | Date | Sat, 03 Apr 2004 07:51:44 -0500 |
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Andreas Hartmann wrote: > Mikhail Ramendik wrote: > >> Hello, >> >> I have an computer with an AMD Duron, and the motehrboard chipset is VIA >> KT133. The hard drive is a Seagate Barracuda 7200.7 ; no other EIDE >> devices are attached. >> >> I run an RH9-based distro, and added a 2.6.4 kernel to it. The following >> problem was tested with two kernel variants: 2.6.4+wolk2/0 with >> preeemption enabled, and 2.6.4 plain from kernel.org with preemption >> disabled. No difference. >> >> I noticed performance problems with 2.6.4, and tracked them to strange >> HDD behavior. >> >> It turned out that on disk-intensive operation, the "system" CPU usage >> skyrockets. With a mere "cp" of a large file to the same direstory >> (tested with ext3fs and FAT32 file systems), it is 100% practically all >> of the time ! > > > Which tool do you use for measure? xosview? > > I'm having here the same problem. But it depends on the tool which is > used for measuring. If I use top from procps 3.2, I can't see this high > system load. "time" can't see it, too. > > This is what top says during cp of 512MB-file: > Cpu(s): 2.0% us, 8.3% sy, 0.0% ni, 0.0% id, 89.0% wa, 0.7% hi, > 0.0% si > > New is "wa", what probably means "wait". This value is very high as long > as the HD is writing or reading datas: > > cp dummy /dev/null > produces this top-line: > Cpu(s): 3.0% us, 5.3% sy, 0.0% ni, 0.0% id, 91.0% wa, 0.7% hi, > 0.0% si
Yes "wa" is not intuitive, some other operating systems use "wio" for "wait i/o" time. As noted in the other thread, you can try the deadline elevator or increased readahead for your load. > > and time says: > real 0m53.195s > user 0m0.013s > sys 0m2.124s > > > But you're right, 2.6.4 is slower than 2.4.25. See the thread "Very poor > performance with 2.6.4" here in the list.
Much discussed, not overly fixed :-(
-- bill davidsen <davidsen@tmr.com> CTO TMR Associates, Inc Doing interesting things with small computers since 1979 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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