Re: NSOperation Efficiency
Re: NSOperation Efficiency
- Subject: Re: NSOperation Efficiency
- From: "Gerriet M. Denkmann" <email@hidden>
- Date: Wed, 05 Dec 2012 08:02:33 +0700
On 5 Dec 2012, at 02:58, Kyle Sluder <email@hidden> wrote:
> On Tue, Dec 4, 2012, at 10:15 AM, Gerriet M. Denkmann 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?
>
> How many operations are you creating? We've found that with more than a
> few hundred operations, NSOperationQueue is unusable.
In this test I was using 444 operations. Otherwise there might be many thousands.
Just tried again with 44 operations, but did not see any change in average execution time.
Kind regards,
Gerriet.
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