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Re: NSRunLoop Tidying
From: |
Dr. H. Nikolaus Schaller |
Subject: |
Re: NSRunLoop Tidying |
Date: |
Sat, 9 Oct 2010 13:49:46 +0200 |
Am 09.10.2010 um 13:19 schrieb David Chisnall:
> meaning that we spend a lot more time sleeping in userspace waiting for the
> kernel to wake us up
Let me ask a fundamental question: do we really have a performance problem to
solve here?
Are any measurements available that a typical application spends more than some
% in this code?
In my understanding, the timers and the untilDate: are handled only once per
loop and then the kernel sleeps. Sometimes for minutes until the user moves the
mouse or clicks a key. The same will happen with any alternative mechanism. I
think your proposal will only simplify calculation how long to sleep and
setting up the kernel to do so. But not improve the sleep time.
The only situation where I can see that setting up the triggers as fast as
possible is if you have timers that expire in fractions of milliseconds. But do
we have a single example where this is required? Another area could be file
handles for network stacks. Do we have a performance bottleneck there?
I have a little the impression that the proposal is just for clearness of the
code or "innovation" for innovation's sake?
I fear a little by leaving POSIX we deviate from the least common denominator
of all UNIX systems and introduce more dependencies.
I don't want to argue against innovation, but it must really improve something.
So I would propose that you work on a code branch that demonstrates that it
works (better).
Best regards,
Nikolaus