Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz?

bert hubert
2007-02-20T22:17:23Z

On Tue, Feb 20, 2007 at 02:02:00PM -0800, Rick Jones wrote:

> The slope appears to be flattening-out the farther out to the right it
> goes. Perhaps that is the length of time it takes to take all the
> requisite cache misses.

The rate of flattening out appears to correlate with the number of processes
running, even though the system is otherwise >99.5% idle during my
measurements.

With only 'gdm' running, things flatten out slowly, iow, it takes longer
delays to see recvfrom slow down. With only 1 process running (init=bash),
the graph is nearly flat.

>From this, it is probable that even an idle GNOME desktop (Ubunty Edgy Eft)
is under fierce cache pressure, enough to blow away my meagre 1MB in a
matter of milliseconds.

I'm trying to figure out which processes have the most impact, I had already
killed anything non-essential. But that still leaves 140 pids.

Bert

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