Re: [tbench regression fixes]: digging out smelly deadmen.

Mike Galbraith
2008-10-26T10:23:44Z

On Sun, 2008-10-26 at 02:11 -0700, Andrew Morton wrote:

> Was this when we decreased the default value of
> /proc/sys/vm/dirty_ratio, perhaps? dbench is sensitive to that.

Wow, indeed. I fired up an ext2 disk to take kjournald out of the
picture (dunno, just a transient thought). Stock settings produced
three perma-wrecks in a row. With it bumped to 50, three very
considerably nicer results in a row appeared.

﻿2.6.26.7-smp dirty_ratio = 10 (stock)
Throughput 36.3649 MB/sec 160 procs
Throughput 47.0787 MB/sec 160 procs
Throughput 88.2055 MB/sec 160 procs

2.6.26.7-smp dirty_ratio = 50
Throughput 1009.98 MB/sec 160 procs
Throughput 1101.57 MB/sec 160 procs
Throughput 943.205 MB/sec 160 procs
﻿
-Mike