[Mono-dev] difference in performance between mono OSX and linux?

[Rodrigo Kumpera]

On Mon, Jan 23, 2012 at 12:18 PM, Jonathan Shore
<jonathan.shore at gmail.com>wrote:

>
> On Jan 23, 2012, at 7:27 AM, Rodrigo Kumpera wrote:
>
> Mono os OSX has some performance issues due to multiple factors, some
> Reimer pointed out, but it's hard to tell without a good profiler run.
>
> Boehm doesn't support the fast memory allocator on OSX.
> The lack of compiler support for fast TLS is another pain point, this has
> been mostly addressed on trunk so 2.12 will be closer.
> Another issue is that OSX primitives are much worse than linux's. Things
> like mutex'es and semephores perform much worse.
> Finally, the 32 x 64 bits issue can make a huge difference depending on
> your code. If you're doing a lot of 64bits math or your
> code is register happy, 32bits will be slower.
>
>
> I see.  I am using a SpinLock around every (very short lived) transaction.
>   Perhaps the primitives used in SpinWait have a different performance
> profile on OSX vs Linux?   Also, all of the transactions involve longs and
> doubles {comparisons, load/store, some arithmetic).   I am not at all clear
> on how longs and doubles would be rendered differently in terms of
> instructions on 32bit vs 64bit.    I thought even in the 32bit world, intel
> CPUs had a 64bit pipeline for doubles, though probably not for longs.
>

doubles have hardware support on 32 and 64bits. longs don't have any under
32bits and things like division are done in software.



> What sort of instrumentation would be useful?
>

Nothing fancy, high frequency sampling to see what runtime code shows up.
On instruments this the template under: Mac OS X -> CPU -> Timer Profiler.
Then customize it from a sample every 1ms to every 100 us.
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