> I do want to point out that interrupt coalescing also has its draw
> backs. Many people discussed all the good things so lets underscore the
> bad. Networks that have trickling amounts of packets are hurt by
> coalescing. Most notably are interactive things like typing in ftp and
> ssh. Since the card is going to collect several packets you basically
> always hit the coalescing timer slowing the overall throughput down to
> whatever your timeout is.
>
> The big issue with coalescing is that it is good for some loads and bad
> for others. So if you can't predict your load it will either hurt you
> or help you. So far I have never seen a heuristic that works well both
> ways.
>
> Also what I have seen is that coalescing always hurts disk IO
> performance. Every time I tinkered with this it had a negative impact.
> The caveat here is that NICs generate interrupts at a completely
> different order of magnitude.
>
> On Fri, Sep 07, 2007 at 02:31:15AM +0000, Sam Fourman Jr. wrote:
> > hello misc@
> > from the page
http://www.openbsd.org/42.html , one of the changes made
> > to OpenBSD 4.2 is
> >
> > A change in the way the kernel random pool is stirred greatly
> > increases performance with network interface cards that support
> > interrupt mitigation, especially on architectures where reading the
> > clock is expensive (such as amd64).
> >
> > What would be some Examples of Network Cards that Support "interrupt mitigation"
> >
> > I guess on this Subject I need educated because I am not all together
> > sure what interrupt mitigation is and why I want it.
> >
> >
> > Thank you for another GREAT release
> >
> > Sam Fourman Jr.
> >
>
