Re: Re: Xcode use 4 cores?
Re: Re: Xcode use 4 cores?
- Subject: Re: Re: Xcode use 4 cores?
- From: "Shawn Erickson" <email@hidden>
- Date: Thu, 17 Aug 2006 10:43:30 -0700
On 8/17/06, Shawn Erickson <email@hidden> wrote:
On 8/17/06, Jim McKinnon <email@hidden> wrote:
> I read a review on Anandtech (http://www.anandtech.com/mac/
> showdoc.aspx?i=2816) and going from dual to 4 cores did not speed up
> compile times. This was surprising as xcode being multi-threaded.
>
> Is this a bug or a real limitation?
Ah I guess you are talking about the dual/quad listing they have for
the Mac Pro. They didn't say how they disabled the extra cores but I
bet that they really had 4 cores in use in all Xcode tests (or
possible only 2 cores in all tests). Xcode will use 4 cores if for are
available.
As an example on my Quad G5...
[../someprojectdirectory/]> time xcodebuild clean build
...with 3 cores disabled (1 active)...
real 2m30.205s
user 1m24.597s
sys 0m34.000s
...with 2 cores disabled (2 active)...
real 1m45.270s
user 1m28.318s
sys 0m39.853s
...with 1 core disabled (3 active)...
real 0m59.437s
user 1m28.230s
sys 0m44.606s
...with 0 cores disabled (4 active)...
real 0m51.615s
user 1m30.205s
sys 0m49.634s
So unless the Mac Pro is reporting the wrong number of cores or Xcode
is reading the wrong number of cores when on a Mac Pro I would bet
something was wrong in either the graph or their test configuration
when doing the Xcode test.
(didn't focus on how many cores Xcode was using on the Mac Pro systems
I used at WWDC 2006 so I cannot eliminate a possibility of a bug)
-Shawn
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