Re: kernels and b0xen
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:
> > > that may be because of the smallish amount of RAM on this thing;
> > > interleaved i was getting pretty much the same ratings. it may have to
> > > do with the RAM sticks' actual ms speed rating - i have 4MB sticks @ 70
> > > ms IIRC, and some 8MB sticks @ 60 ms.
> >
> > us (microseconds), I guess?
>
> 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
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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