Date: Thu, 14 Jun 2007 11:45:12 -0400
From: Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Cygwin allocted time slice
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On Thu, Jun 14, 2007 at 04:20:04PM +0100, Aaron Gray wrote:
>> On Thu, Jun 14, 2007 at 04:15:40AM +0100, Aaron Gray wrote:
>>> Cygwin seems to only use a small amount of time slice relative to the
>>> ammount of time slice availiable.  Compiles, builds and testsuite are
>>> relly slow compared to MinGW which takes too much time.
>>>
>>> 'time' results confirm this.  Process time is about 1/4 of the total
>>> system time.
>>>
>>> It i very noticable on compiling and testing GCC as compared to the
>>> same on Linux or MinGW.
>>>
>>> Is there any way to give Cygwin a bigger slice of the pie ?
>>>
>>> Say 50% or 75% ?
>>
>> How do you suppose Cygwin is managing this interesting feat of only
>> using some of the CPU time?  What Windows API is Cygwin using to just
>> grab a small slice of the time?
>
> Weird I was getting very long compile times for GCC and on using 'time' was 
> getting indications that make was only getting 25% of total system time.
>
> I'll see if it is repeatable on another system.
>
>> As a follow-up question:  Why do you suppose we are punishing you by
>> not allowing Cygwin to use all of the CPU by default?
>>
>> Oh.  Wait.  WJM.  Nevermind.
>
> Weird reply, no need to take the micky !

You have apparently made an assumption that Cygwin is purposely using
only a part of the CPU.  What's weird about asking for your rationale
for why anyone would write a program which did such a thing, leaving it
to some undocumented procedure to get better performance?  Why do you
think we wouldn't just make this the default?

In other words: your assumptions don't make a lot of sense.

Here are some better assumptions:

1) Hey!  Maybe, since 'time' is a linux program, whatever is needed to get
it to work accurately isn't well-implemented in Cygwin, so you can't trust
its output.

2) Hey!  I just remembered that Cygwin is an emulation layer on top of
Windows.  That means that there is a lot more code being executed than
would be the case for MinGW!  Maybe *that's* why things are slower!

cgf

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