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From Jim Jagielski <>
Subject Re: timeout queues in event mpm
Date Mon, 14 Nov 2011 02:04:10 GMT
Yeah, I saw your tweet… This is really cool and I never bothered
to check raw req/per/sec stuff for my acna11 talk because,
as it was said in the trafficserver talk, rps is ridiculous
anyway ;)

Would love to see this folded into trunk and even 2.4.0
if we have the time and inclination. When I get back to the
office (still in SF), I hope to commit some Simple patches
that I've been playing around with.

On Nov 13, 2011, at 4:24 PM, Paul Querna wrote:

> I've created a branch event-performance with this change and several
> other changes:
> <>
> I did some basic benchmarking to validate it, though if anyone has a
> real test lab setup that can throw huge traffic numbers at it that
> would be very helpful.
> For the "It works" default index page, I got the following:
> event mpm trunk: 15210.07 req/second
> event mpm performance branch: 15775.42 req/second (~4%)
> nginx 0.7.65-1ubuntu2: 12070.35
> Event MPM was using a 100% default install configuration, nginx was
> using Ubuntu 10.04.3 LTS default configuration, baring replacement of
> the index.html to match Apache's.  I included nginx just to make sure
> the we were in the same ballparks, I imagine a well tuned nginx config
> can go much higher, but the same is true of Apache too :)
> As an aside, In either case, using apachebench for this is kinda..
> pointless, it's maxing itself out on a single core, and the machine
> is... idle.  I'd be very happy if someone wrote a new benchmarking
> tool and/or revamped flood. sigh.
> Will try to do some more profiling and then get this into trunk in the
> next day or two.
> On Fri, Nov 11, 2011 at 8:07 PM, Paul Querna <> wrote:
>> hi,
>> After r1201149, we now lock for lots of things, where in an ideal
>> case, we shouldn't need it.
>> I'm toying around with ideas on how to eliminate the need for a mutex at all.
>> My current 'best' idea I think:
>> 1) Create a new struct, ap_pollset_operation_and_timeout_info_t, which
>> contains a what pollset operation to do (Add, Remove, Flags),
>> timeout_type, the timeout value, and a pointer to the conn_rec.
>> 2) Implement a single-reader single writer circular ring buffer of
>> these structures. (Using 2x uint16_t head/end offsets stuffed into a
>> single uint32_t so we can make it portability atomic using
>> apr_atomic_cas32)
>> 3) Allocate this ring buffer per-worker.
>> 4) Have the single Event thread de-queue operations from all the worker threads.
>> This would remove the 4 or 5 separate timeout queues we have
>> developed, and their associated mutex, and basically move all of the
>> apr_pollset operations to the single main thread.
>> Without modification to the event mpm, it would potentially cause some
>> issues as the event thread isn't always waking up that often, but I
>> think we can figure out a way to do this without too much pain (either
>> a pipe trigger to wake up when in 'slow mode', or just lower the
>> default timeout on the pollset form 500ms to like 5ms).
>> Thoughts?
>> Thanks,
>> Paul

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