One-shot semantics in GHC event manager

[Ben Gamari]

Kazu Yamamoto <kazu at iij.ad.jp> writes:

> Hi,
>
>>> Andreas - want me to go ahead and get you some hardware to test Ben's
>>> patch in the mean time? This way we'll at least not leave it hanging
>>> until the last moment...
>> 
>> I will also try this with two 20-core machines connected 10G on
>> Monday.
>
> I measured the performace of GHC head, 7.8.3 and 7.8.3 + Ben's patch
> set.
>
> Server: witty 8080 -r -a -s +RTS -N<n> *1
> Measurement tool: weighttp -n 100000 -c 1000 -k -t 19 http://192.168.0.1:8080/
> Measurement env: two 20 core (w/o HT) machines directly connected 10G
>
> Here is result (req/s):
>
> -N<n>          1       2        4        8        16
> ---------------------------------------------------------
> head           92,855  155,957  306,813  498,613  527,034
> 7.8.3          86,494  160,321  310,675  494,020  510,751
> 7.8.3+ben      37,608   69,376  131,686  237,783  333,946
>
> head and 7.8.3 has almost the same performance. But I saw significant
> performance regression in Ben's patch set.
>
Hmm, uh oh.  Thanks for testing this. I'll try to reproduce this on my
end. It looks like it shouldn't be so hard as even the single-threaded
performance regresses drastically. Just to confirm, you are using the
latest revision of D347?

Cheers,

- Ben
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