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Re: Cygwin slow on x64 systems
- From: Magnus Holmgren <magnushol at gmail dot com>
- To: cygwin at cygwin dot com
- Date: Wed, 1 Sep 2010 17:12:19 +0000 (UTC)
- Subject: Re: Cygwin slow on x64 systems
- References: <4C7B9327.9030204@graphtech.co.il> <loom.20100831T222419-914@post.gmane.org>
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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