Re: Message Forwarding Overhead / Performance
Re: Message Forwarding Overhead / Performance
- Subject: Re: Message Forwarding Overhead / Performance
- From: Bill Bumgarner <email@hidden>
- Date: Tue, 28 Oct 2008 15:37:03 -0700
On Oct 28, 2008, at 3:16 PM, Jerry Krinock wrote:
On 2008 Oct, 28, at 9:09, Bill Bumgarner wrote:
That would not surprise me. An absolute microseconds overhead
isn't a terribly useful measure without knowing the total # of
microseconds. In general, measuring as a factor of speed -- 1.2x
20x 200x is more widely applicable (tends to be more consistent
across different CPUs, for example).
Well, since you asked..... :))
Actually, I calculated this first but it seemed too ridiculous to
publish.
Time to send message and
do 10,000 integer additions
---------------------------
Direct messaging 250 microseconds typical
Message Forwarding 300000 microseconds typical
"X" factor: 1200 X
Obviously this is because the "real work" was trivial. But I
concocted my test that way purposely. The result of "20 microseconds
per message on a 2006 Mac Mini" gives me a measure which I can use
to ^predict^ performance in this and future applications ^before^
writing code.
Oooh... trivial tests! I like those! Can you share the code?
So... sure... message forwarding is slow. But does it matter in
your application?
Early in the design process you need to make some guesses based on
experience. Since I have an alternative to in this case, the
decision is to use the alternative.
Roughly, the lesson is: Don't use message forwarding for "actual
work". I was just wondering if anyone had ever found otherwise.
I'd rephrase that for archival purposes: Don't use message
forwarding in tight loops or other repetitive use patterns. It
doesn't make sense to have to figure out who is really going to do the
work on each pass through a loop when figuring out who is so terribly
expensive.
b.bum
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