* Mike Silbersack <[EMAIL PROTECTED]> [011012 01:30] wrote:
> Well, I've been watching everyone argue about the value of interrupt
> coalescing in the net drivers, so I decided to port terry's patch to 4.4 &
> -current to see what the results are.  The patch included applies cleanly
> to 4.4's if_dc, and will apply to -current with a one line change.
> Whitespace is horrible, I copied and pasted the original patch, used patch
> -l, etc.
> The test setup I used was as follows:
> Duron 600, PNIC, running -current
> Celeron 450, ADMtek tulip-clone, running -stable
> The network is 100mbps, switched.  To simulate load, I used a syn flooder
> aimed at an unused port.  icmp/rst response limiting was enabled.

Actually, you might want to leave that on, it will generate more load.

> With the -current box attacking the -stable box, I was able to notice a
> slight drop in interrupts/second with the patch applied.  The number of
> packets was ~57000/second.
> Before: ~46000 ints/sec, 57-63% processor usage due to interrupts.
> After: ~38000 ints/sec, 50-60% processor usage due to interrupts.
> In both cases, the box felt responsive.

You need to get real hardware to run these tests, obviously you aren't
saturating your line.  I would suspect a better test would be to see
how many pps you get can at the point where cpu utlization reaches
100%.  Basically start at a base of 60,000pps, and see how many more
it takes to drive them both to 100%.

Even your limited tests show a mean improvement of something like

10% isn't earth shattering, but it is a signifigant improvement.


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