Re: kernels and b0xen
On Thu, Jan 23, 2003 at 13:48:29 +0100, Geert Uytterhoeven composed:
> On Thu, 23 Jan 2003, Gabriel Paubert wrote:
> > On Thu, Jan 23, 2003 at 12:12:56PM +0100, Geert Uytterhoeven wrote:
> > > On Thu, 23 Jan 2003 simon@nuit.ca wrote:
> >
> > Better but not quite yet, only 3 orders of magnitude off instead of 6 ;-)
> > Memory access times were already counted in nanoseconds 25 years ago.
>
> Oops ;-)
>
> > > BTW, I get 45 MB/s for the buffer-cache on my 66 MHz SDRAM.
> >
> > Looks still very low, very conservative bridge timings? This means a
> > cache line read (32 bytes) every 700ns or so. Even if you dirty every
> > cache line, doubling the traffic, this means 350ns per burst transfer.
>
> Note these are the results of `hdparm -T', not from a real memory benchmark.
> Real memory read performance is ca. 100 MB/s, which is reasonable for machines
> of that age, cfr. http://home.tvd.be/cr26864/Linux/PPC/MemSpeed.html
hm, well other than the cache on the CPU and the RAM and disk caches, i
don't have a cache per se, i.e., on mobo L2 cache. this could be making
a rather large difference. i didn't realise that until now.
simon
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
>
>
> --
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