Re: [patch part 2] Re: [patch] Re: PostgreSQL pgbench performance regression in 2.6.23+

Mike Galbraith
2008-06-07T18:19:25Z

On Sat, 2008-06-07 at 19:53 +0200, Mike Galbraith wrote:
> On Sat, 2008-06-07 at 18:12 +0200, Peter Zijlstra wrote:

> > Just wondering, how much effect does the last_preempter stuff have?, it
> > seems to me the minimum runtime check ought to throttle these wakeups
> > quite a bit as well.
>
> Without last_preempter, you'd have all tasks having a minimum runtime.
> That would harm the single cpu starve.c testcase for sure, and anything
> like it. I wanted to target this pretty accurately to 1:N type loads.
>
> If you mean no trying to disperse preempters, I can test without it.

pgbench
2.6.26-rc5+ 2.6.26-rc5+ with no disperse
1 10165.511814 10183.705908 10191.865953 10186.995546
2 14994.697875 15204.900479 15209.856474 15239.639522
3 16554.371722 17279.376443 16431.588533 15828.812843
4 18447.345925 18088.861169 15967.533533 16827.107528
5 20119.250823 18537.351094 17890.057368 18829.423686
6 21439.841579 22634.887824 18562.389387 18907.807327
8 25579.379337 25908.373483 19527.104304 19687.221241
10 23876.035623 22403.867804 22635.429472 20627.666899
15 23276.797649 23595.597093 22695.938882 22233.399329
20 23603.315133 23256.506240 22623.205980 22637.340746
30 23633.448266 23229.286697 22736.523283 22691.638135
40 22925.552706 23081.526954 20037.610595 22174.404351
50 19102.481374 19558.624434 21459.370223 21664.820102