Re: NSOperation Efficiency
Re: NSOperation Efficiency
- Subject: Re: NSOperation Efficiency
- From: "Gerriet M. Denkmann" <email@hidden>
- Date: Wed, 05 Dec 2012 02:01:05 +0700
On 5 Dec 2012, at 01:55, Mike Abdullah <email@hidden> wrote:
> If your operations are purely CPU-bound, the whole point of GCD is to manage this for you. With the default number of concurrent operations, NSOperationQueue does exactly that. Have you tried with that setting?
I have, and it makes my app unresponsive (i.e unusable) until all operations have finished.
Triggered by making other app, active, then again my app.
>
> On 4 Dec 2012, at 18:15, "Gerriet M. Denkmann" <email@hidden> wrote:
>
>> I have an app which uses NSOperations inside an NSOperationQueue. These operations do not do any I/O - just Cpu. No swapping is taking place.
>>
>> When I set [ self.operationQueue setMaxConcurrentOperationCount: 1 ] each operation takes on average 200 msec., measured by NSDate.
>>
>> With 2 concurrent operations, it takes not 100 msec but 110 - an extra 10%. Ok - some overhead is to be expected.
>>
>> With 4 ops it takes 70 instead of 50 - overhead 40% - rather a lot.
>> With 8 ops it takes 60 instead of 25 - overhead 140%. or: 40% of the cpu is used by my operations, 60% is used by whom? And for what?
>>
>> Is this to be expected? Or does my app has some hidden flaws? If so, where should I start looking?
>>
>> Gerriet.
>>
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