Cygwin slow on x64 systems

Christopher Faylor
Wed Sep 1 19:10:00 GMT 2010

On Mon, Aug 30, 2010 at 02:16:55PM +0300, Sagi Ben-Akiva wrote:
>For the last couple of weeks I'm trying to identify the cause for cygwin 
>slowdown on x64 machines which was reported by David Morgan about 6 
>months ago.
>Using cvsps I was able to generate a patchset which contains all the 
>changes between those 2 revisions.
>I then applied the changes one by one and built cygwin1.dll for each 
>change, then I ran my test script again for each cygwin1.dll version and 
>I found that the change to winsup/cygwin/ from '2006/03/12 
>23:57:03' introduce this issue.
>The log for this change is :
>* (dll_crt0_0): Call sigproc_init during init startup.
>(_dll_crt0): Don't worry about sync_startup.  Just wait for sigthread here.
>This change includes 2 different sub-changes :
>1. Moving the call to sigproc_init from dll_crt0_1 function to 
>dll_crt0_0 - which doesn't affect performance.
>2. a. Moving the call to wait_for_sigthread from dll_crt0_1 to _dll_crt0 
>which calls dll_crt0_1.
>    b. Deleting the call to WaitForSingleObject,
>       i.e. : "Don't worry about sync_startup"
>I can confirm that the 2nd sub-change is the cause for the slowdown.
>Any help will be appreciated.

I rewrote the signal initialization stuff today and have generated a
new snapshot.  Please let me know if this works better for you.  I haven't
actually tried to run a fork per sec.  test yet so there may be other
lurking problems.


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