Messages in this thread | | | Subject | Re: 2.4.17: pwrite destroys block I/O throughput | From | "Jeffrey W. Baker" <> | Date | 30 Jan 2002 15:35:53 -0800 |
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On Wed, 2002-01-30 at 14:55, Jeffrey W. Baker wrote: > Hi there, > > I've never heard of pwrite and pread before, but htdig apparently makes > very heavy use of it. On my 2.4.17 SMP 2GB HIGHMEM + ext3 system, > running htdig destroys input rates for every other process. htdig's > output proceeds at approximately 2MB/s, but input for the entire system > runs only at about 4KB/s (YES, KB!). If I suspend htdig, system block > input increases to the normal rate of 10-50MB/s. Output still works, as > a dd from /dev/zero to a 400MB file runs at about 25MB/s.
I looked around a little more and it seems that htdig is doing SYNC I/O on its db2 files. This may be the problem. If so, it seems that sync I/O is able to DoS all other I/O consumers on the machine.
-jwb
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