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From: Magnus Holmgren <magnushol AT gmail DOT com>
Subject: Re: Cygwin slow on x64 systems
Date: Wed, 1 Sep 2010 17:12:19 +0000 (UTC)
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Magnus Holmgren <magnushol <at> gmail.com> writes:

> I did some testing on my 64-bit Vista system, and it appears that 
> CreateThread is the main cause.

I think I've found the reason for the slow CreateThread. It seems like
the following remark in the MSDN documentation is relevant, at least for
WOW64 processes:

 * During process startup and DLL initialization routines, new threads can
   be created, but they do not begin execution until DLL initialization is
   done for the process.

To test this, I removed the call to sigproc_init in dll_crt0_0 and made sure 
it was always called in dll_crt0_1 instead. Suddenly the sigp thread started 
executing immediately, and its initialization was complete long before 
wait_for_sigthread was called.

Even with this change, a "date loop" isn't blazingly fast on my computer
(cygwin1.dll created from 1.7.7 sources, first number is executions per
second):

     26 Wed Sep  1 18:47:36 WEDT 2010
     27 Wed Sep  1 18:47:37 WEDT 2010
     26 Wed Sep  1 18:47:38 WEDT 2010

But it is a clear improvement (using the stock 1.7.6 dll):

      9 Wed Sep  1 18:52:35 WEDT 2010
      9 Wed Sep  1 18:52:36 WEDT 2010
      9 Wed Sep  1 18:52:37 WEDT 2010

PS. There are a few trace printfs in cygthread::create that uses "name" in 
the argument list to print the thread name. That doesn't work nearly as well 
as "__name". :)

  Magnus



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