Re: Linux 2.6.6-rc3

[Andrew Morton <akpm@osdl.org>]

Craig Thomas <craiger@osdl.org> wrote:
>
> I have taken a quick look at the results and I see no degredations
>  from 2.6.6-rc2 and the performance looks much better than the 
>  2.6.5 kernel for dbt3 (as reported earlier).

The 70% dbt3 improvement is extremely fishy.  Yes, there are things in
2.6.6-rc3 which could improve database workloads by that much, but dbt3
doesn't appear to be using them.

Again, the vmstat traces indicate that after a run on 2.6.6-rc3 we have a
full gigabyte less used pagecache than with 2.6.5.  In both cases there is
still a lot of free memory.  Which tends to indicate that the -rc3 run was,
for some reason, not an equivalent workload - it's using a smaller dataset.

I'd suggest that you double-check these results, try and work out why the
-rc3 run is touching less data.  Maybe go back and redo the 2.6.5 test?