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
>> bottlenecks
>> 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.


Hmm ok,

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.
>
> John


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