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

Con Kolivas
2002-09-23T03:45:39Z

Quoting Daniel Jacobowitz <dan@debian.org>:

> 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?

Correct. contest was run with gcc2.95.3 only. The kernels were compiled with
2.95.3 and 3.2 respectively.

Con.