Basically you measure the main memory bandwidth for copying.
So, you should expect: ~50MB/s with Pentium and ~100MB/s with P-II (100MHZ
FSB), as reported by the ctcm tool. (c't cache monitor, www.heise.de/ct)
P-II does what it's expected to: 100MB/s.
I don't know exactly, why Pentium is slower than expected. It may be Linux
buffer cache handling overhead (not very likely). I think it's some of the
strangenesses of Pentium architecture.
Memory copying speed on a Pentium depends on whether you
* use movb or movl or use fpu
* implement software write allocation (loading target L1 cache lines)
* how many bytes you copy within the loop body (branch prediction issue?)
I don't know what mechanism the linux buffer cache uses.
I've seen 36MB/s on my old Cx6x86-P200+ (2x75MHz), IIRC.
Regards,
-- Kurt Garloff <K.Garloff@ping.de> (Dortmund, FRG) PGP key on http://student.physik.uni-dortmund.de/homepages/garloff- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/