Re: Bad SSD performance with recent kernels

[Shaohua Li]

2012/1/30 Eric Dumazet <eric.dumazet@xxxxxxxxx>:
> Le lundi 30 janvier 2012 à 11:17 +0800, Shaohua Li a écrit :
>
>> 1M block size is slow, I guess it's CPU related.
>>
>> And as for the big regression with newer kernel than 2.6.38, please
>> check if idle=poll
>> helps. CPU idle dramatically impacts disk performance and even latest
>> cpuidle governor
>> doesn't help for some CPUs.
>>
>
> No change with idle=poll
I mean the big regression might be related to CPU idle. because I
saw really bad performance with CPU idle with some CPUs.

The 1M block size performance is lower than 128K is not. but I still
guess it's CPU related (like copy). The test result is always like this
IIRC.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/