Re: DBT-2 anticipatory scheduler and filesystem results with 2.6.1

Nick Piggin
2004-01-20T04:56:10Z

Andrew Morton wrote:

>markw@osdl.org wrote:
>
>> I ran some dbt-2 tests against 5 filesystems with 2.6.1-mm4 and 2.6.1. I
>> see a degradation from 0 to 7% in throughput.
>>
>
>-mm4 also had readahead changes which will adversely impact database-style
>workloads. I'd suggest that you revert
>
>ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.1/2.6.1-mm4/broken-out/readahead-revert-lazy-readahead.patch
>
>and retest.
>
>We reverted lazy readahead because it broke NFS linear reads and was doing
>the wrong thing anyway. We need to come up with something else for
>database-style workloads.
>
>

Oh good. I'd be a bit surprised if it were due to an as-iosched.c change
that
caused the regression.

But there are changes in how new processes are handled, so if you have a lot
of io submitting processes being created, you might see a difference.