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

From: Mike Galbraith <[email-masked]>
Date: Mon, 27 Oct 2008 10:29:17 +0100

On Sun, 2008-10-26 at 20:03 +0100, Jiri Kosina wrote:
> On Sun, 26 Oct 2008, Andrew Morton wrote:
> 
> > > > > 208.4 MB/sec  -- vanilla 2.6.16.60
> > > > > 201.6 MB/sec  -- vanilla 2.6.20.1
> > > > > 172.9 MB/sec  -- vanilla 2.6.22.19
> > > > > 74.2 MB/sec   -- vanilla 2.6.23
> > > > >  46.1 MB/sec  -- vanilla 2.6.24.2
> > > > >  30.6 MB/sec  -- vanilla 2.6.26.1
> > > > > I.e. huge drop for 2.6.23 (this was with default configs for each 
> > > > > respective kernel).
> > Was this when we decreased the default value of
> > /proc/sys/vm/dirty_ratio, perhaps?  dbench is sensitive to that.
> 
> 2.6.28 gives 41.8 MB/s with /proc/sys/vm/dirty_ratio == 50. So small 
> improvement, but still far far away from the throughput of pre-2.6.23 
> kernels.

How many clients?

dbench 160 -t 60

2.6.28-smp (git.today)
Throughput 331.718 MB/sec 160 procs (no logjam)
Throughput 309.85 MB/sec 160 procs (contains logjam)
Throughput 392.746 MB/sec 160 procs (contains logjam)

	-Mike