> it? I tried one 1.5 GB file, it was oopsing
Jamal, you say this as something normal. 8)
Seems, this is the most interesting statement of your report.
You could tell where did it oops at least.
> So i figured, no problem i'll re-run it with a file 10 times larger.
> **I was dissapointed to see no improvement.**
You should see much worse behaviour in this case.
> cant trace it. So i am using about 170M which is read about 8 times in
> the 15 secs
You forgot to say how much of memory you machine has. 8)
Page cache works as soon as pages are not pushed out of cache.
In order to compare to write() from vm you must make the following things:
1. Use write() buffer not fitting to L2 cache. Otherwise you measure
bandwidth of L2 cache, and in the case of ttcp it is even bandwidth
of L1 cache. It will beat any zero copy, no doubts.
2. Take moderately large file, not pushed out from page cache
> - Given Linux's non-pre-emptability of the kernel i get the feeling that
It is scheduled each sndbuf in the _worst_ case.