Re: [BENCHMARK] 2.4.{18,19{-ck9},20rc1{-aa1}} with contest

[Jens Axboe <axboe@suse.de>]

On Fri, Nov 08 2002, Andrew Morton wrote:
> Con Kolivas wrote:
> > 
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > 
> > >Con Kolivas wrote:
> > >> io_load:
> > >> Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
> > >> 2.4.18 [3]              474.1   15      36      10      6.64
> > >> 2.4.19 [3]              492.6   14      38      10      6.90
> > >> 2.4.19-ck9 [2]          140.6   49      5       5       1.97
> > >> 2.4.20-rc1 [2]          1142.2  6       90      10      16.00
> > >> 2.4.20-rc1aa1 [1]       1132.5  6       90      10      15.86
> > >
> > >2.4.20-pre3 included some elevator changes.  I assume they are the
> > >cause of this.  Those changes have propagated into Alan's and Andrea's
> > >kernels.   Hence they have significantly impacted the responsiveness
> > >of all mainstream 2.4 kernels under heavy writes.
> > >
> > >(The -ck patch includes rmap14b which includes the read-latency2 thing)
> > 
> > Thanks for the explanation. I should have said this was ck with compressed
> > caching; not rmap.
> > 
> 
> hrm.  In that case I'll shut up with the speculating.
> 
> You're showing a big shift in behaviour between 2.4.19 and 2.4.20-rc1.
> Maybe it doesn't translate to worsened interactivity.  Needs more
> testing and anaysis.

The merging and seek accounting in 2.4.19 is completely off, it doesn't
make any sense. 2.4.20-rc1 should be sanely tweakable.

-- 
Jens Axboe