Rather than cobble together your own measurement infrastructure using
old Carbon calls and NSLog, I recommend in the strongest possible
terms that you measure your application's performance using purpose-
built profiling and analysis tools like Shark and Instruments.
Performance measurement may seem simple at first glance but it can be
very subtly hard to get right. That's why tools for it are supplied
with Xcode, and why they need explicit support from the operating
system.
-- Chris
On Jan 15, 2009, at 2:16 PM, Jens Bauer <jensba...@christian.net> wrote:
Hi all,
I just want to let you know that I discovered I did a terrible
mistake today.
In other words: you don't have to learn from your own mistakes, if
you can learn from mine. =)
I investigated this, because my rendering was choppy.
The code...
- (void)renderObject
{
}
- (void)renderAll
{
UnsignedWide us;
double time;
Microseconds(&us);
time = ((double) us.hi) * 65536.0 * 65536.0 + ((double) us.lo);
[self renderObject];
Microseconds(&us);
time = ((double) us.hi) * 65536.0 * 65536.0 + ((double) us.lo) -
time;
NSLog(@"time:%.3fms", time * 0.001);
}
..often used around 3ms for the empty method "-renderObject".
It gave me the terrible result of up to 21ms spent in the empty
method!
-So I'd like to let you know that it's sometimes good to think "do I
really need this method?"
I will be rewriting around 8 of my large files for doing some
rendering, so they will be using C-routines instead of ObjC methods,
since I'm using them in a real-time environment.
My guess is that the message dispatcher probably needs to do
something else than servicing *my* application, so I believe it's
the nature of the environment, not a bug.
Love,
Jens
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