Re: [BENCHMARK] gcc3.2 v 2.95.3 (contest and linux-2.5.38)

[Daniel Jacobowitz]

On Sun, Sep 22, 2002 at 08:41:51PM -0700, Andrew Morton wrote:
> Con Kolivas wrote:
> > 
> > I performed contest benchmarks on kernel 2.5.38 when the kernel is compiled with
> > gcc3.2 to gcc2.95.3
> > 
> > warning: The following benchmarks may be disturbing to some viewers:
> > 
> > No Load:
> > Kernel                  Time            CPU
> > 2.5.38                  68.25           99%
> > 2.5.38-gcc32            103.03          99%
> > 
> 
> Try gcc-2.91.66.  It might break the 45 second mark.
> 
> > IO Full Load:
> > Kernel                  Time            CPU
> > 2.5.38                  170.21          42%
> > 2.5.38-gcc32            1405.25         8%
> 
> The streaming write is stalling gcc's read for long enough for gcc's
> working set to be evicted.  And the working set cannot be reestablished
> because the streaming write prevents it.  Meltdown.
> 
> I have fixed this.  Hang around.

That sounds like a slowdown in _running_ GCC... The worrisome part of
Con's post is that he was talking about which compiler he'd built the
kernel with.  Right?

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer