This is a discussion on Re: in-kernel tcp server - FreeBSD ; John Polstra wrote: > Julian Elischer wrote: > >> I would actually like to address the performance issues. >> >> is there any chance the oldest version (4.x based) might be released, >> or at least it would be nice ...
John Polstra wrote:
> Julian Elischer wrote:
>> I would actually like to address the performance issues.
>> is there any chance the oldest version (4.x based) might be released,
>> or at least it would be nice to get the code snippet that attaches to
>> eh ng_ksocket and
>> reads and writes the stream..
>> I could make a TCP ECHO node that way and use it for tracking down the
>> I'm not too interested in the actual webserver itself.
> I don't have the ksocket version any more. It was an early experiment
> (in 2001) that I discarded pretty quickly.
> The later 4.x-based version that bypassed the TCP stack and socket layer
> performed well on uniprocessor systems. I didn't feel netgraph was a
> performance problem at all on that version. But as multiprocessor
> systems became more mainstream, the 4.x version wasn't able to take
> advantage of the added CPUs. Also, it didn't support ACPI and had
> trouble booting on some of the newer hardware.
> For those reasons, I updated to a 7.x-based system. At that point, the
> newer SMP-friendly netgraph started to impact performance pretty
> seriously. The allocation/deallocation of netgraph's queue items seemed
> to be a big part of the problem. In 4.x we just passed mbufs around,
> without any other allocations or deallocations. In 7.x, the mbufs are
> wrapped up in queue items that have to be allocated and freed, and that
> added a lot of overhead. I think also that the reader-writer locking in
> netgraph was impacting performance. It's a really elegant locking
> scheme, but my node graphs were so simple that I didn't really need it.
but if you did find some old ksocket based code sitting around,
i'd love to try it in -current and work on the bottlenecks..
I do need to try fix netgraph bottlenecks...
I'll certainly look at what I can do about the queue items.
I may make a per-cpu cache of them.
> I don't view netgraph as having serious performance problems. It's just
> that I was aiming for maximal performance (in terms of HTTP sessions per
> second), and was willing to do otherwise unreasonable things to get it.
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