Re: Mystery Threads
Re: Mystery Threads
- Subject: Re: Mystery Threads
- From: Quincey Morris <email@hidden>
- Date: Thu, 29 Sep 2016 00:38:38 -0700
- Feedback-id: 167118m:167118agrif8a:167118sPooMdzZJm:SMTPCORP
On Sep 29, 2016, at 00:15 , Gerriet M. Denkmann <email@hidden> wrote:
>
> dispatch_apply( nbrOfThreads, queue, ^void(size_t idx)
>
> As my computer has just 8 CPUs, I thought that using nbrOfThreads > 8 would be silly: adding overhead without gaining anything.
>
> Turns out this is quite wrong. One function (called threadHappyFunction) works more than 10 times faster using nbrOfThreads = a few ten-thousand (as compared to nbrOfThreads = 8).
>
> This is nice, but I would like to know why can this happen.
What makes you think “nbrOfThreads” represents a number of threads?
> Why are the threads seemingly blocking each other?
> What is going on here?
> How can I investigate this?
Isn’t this what Instruments is for?
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