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Message-ID: | <4C7B9327.9030204@graphtech.co.il> |
Date: | Mon, 30 Aug 2010 14:16:55 +0300 |
From: | Sagi Ben-Akiva <sagi AT graphtech DOT co DOT il> |
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To: | cygwin AT cygwin DOT com |
Subject: | Cygwin slow on x64 systems |
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Hello, 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. I wrote a little bash script which prints the result of 'date -s' to a file in a loop and then counts the number of times the same second appears in that file. I used this script to test all available cygwin revisions snapshots (which I downloaded from ftp://www.fruitbat.org/pub/cygwin/circa/index.html) for cygwin version 1.5.19-4. I was able to identify the exact change which introduce the slowdown. With my test script for cygwin version 1.5.19-4, snapshot timestamp 1142005204 I'm able to get ~40 lines/second, but with the same version, snapshot timestamp 1142338816 the result is ~18 lines/second. 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/dcrt0.cc from '2006/03/12 23:57:03' introduce this issue. The log for this change is : * dcrt0.cc (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. Thank you, Sagi. -- Sagi Ben-Akiva - sagi at graphtech dot co dot il GraphTech Computer Systems -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
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