IO To IDE Blocking In 5.1
markir at paradise.net.nz
Fri Aug 29 22:21:43 PDT 2003
I am running Freebsd 5.1 on a Dell 410 with 2xPII and 2xIDE drives (each
on its own channel).
Drive #1 as 1 filesystem mounted on /, drive #2 has 1 filesystem,
mounted on /data1
(both have softupdates enabled)
i) start a process doing some io on drive #1
ii) start iostat 5
iostat blocks until the process is completed. If I start iostat *first*,
then it does not block, and
I can see the io activity generated by the process when it starts.
If I try this test on drive #2, then neither case blocks.
I am running the SMP kernel, but can reproduce this using GENERIC.
Any ideas ?
P.s : This came to my attention whilst experimenting with the smp
kernel, I was able to get nice 2 processer scaling with 2 running
processes *except* if they both needed to do IO (even if they were doing
it on different drives).
Note : Have previously run 5.1 on a HP VE6, and dont recall encountering
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