[mythtv-users] Horrendous RAID-6 performance

[Yan Seiner]

John Drescher wrote:
>>  Could it be a tickless kernel problem?  I just went through the kernel
>>  config and that's the only thing I can think of that looks vaguely
>>  unusual.
>>
>>     
> That is definitely possible and it could be causing an interrupt
> problem causing poor disk performance. I would try building a kernel
> with tickless off or use an older known working kernel.
>   
Well, I just came back from a weekend trip.

selene:/data/home/yan# hdparm -Tt /dev/md10

/dev/md10:
 Timing cached reads:   2480 MB in  2.00 seconds = 1240.82 MB/sec
 Timing buffered disk reads:  770 MB in  3.01 seconds = 255.50 MB/sec

no wait states, cpu usage is down to nothing....

The only thing I did before I left is to change the freq scaling to 
performance:

echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

but at the time that didn't seem to make any difference.  But the CPU 
clock never gets below 2400 (at least from what /proc/cpuinfo says).

Hmmmm.

--Yan

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