X-Recipient: archive-cygwin AT delorie DOT com
X-SWARE-Spam-Status: No, hits=-1.9 required=5.0	tests=BAYES_00,RCVD_IN_DNSWL_NONE,RCVD_IN_HOSTKARMA_YE
X-Spam-Check-By: sourceware.org
X-Mail-Handler: MailHop Outbound by DynDNS
X-Report-Abuse-To: abuse AT dyndns DOT com (see http://www.dyndns.com/services/mailhop/outbound_abuse.html for abuse reporting information)
X-MHO-User: U2FsdGVkX1/uoMJssejVLQKXx6zdqlMG
Date: Wed, 13 Jun 2012 17:40:43 -0400
From: Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Performance problems with emacs-X11 in current cygwin
Message-ID: <20120613214043.GA3554@ednor.casa.cgf.cx>
Reply-To: cygwin AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
References: <4FCB2991 DOT 3010701 AT users DOT sourceforge DOT net> <4FCB5438 DOT 7080903 AT cornell DOT edu> <4FCB9872 DOT 5010506 AT cornell DOT edu> <loom DOT 20120606T123651-460 AT post DOT gmane DOT org> <4FD1F709 DOT 4050107 AT cornell DOT edu> <87k3zhbyyk DOT fsf AT Rainer DOT invalid> <4FD22C39 DOT 6070107 AT cornell DOT edu> <4FD53FA9 DOT 2040105 AT cornell DOT edu> <4FD8DE9C DOT 1090900 AT cornell DOT edu> <4FD90105 DOT 7050701 AT cornell DOT edu>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4FD90105.7050701@cornell.edu>
User-Agent: Mutt/1.5.20 (2009-06-14)
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
Precedence: bulk
List-Id: <cygwin.cygwin.com>
List-Unsubscribe: <mailto:cygwin-unsubscribe-archive-cygwin=delorie DOT com AT cygwin DOT com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

On Wed, Jun 13, 2012 at 05:07:17PM -0400, Ken Brown wrote:
>On 6/13/2012 2:40 PM, Ken Brown wrote:
>> On 6/10/2012 8:45 PM, Ken Brown wrote:
>>> The bisection shows that the first problematic commit is this one:
>>>
>>> http://git.gnome.org/browse/glib/commit/?h=glib-2-32&id=7eae486179e2799c369ed9ffcea663bf9161ce79
>>>
>>>
>>>
>>> Author: Ryan Lortie <desrt AT desrt DOT ca>
>>> Date: Wed Aug 31 22:07:02 2011 -0400
>>>
>>> GMain: simplify logic for g_wakeup_acknowledge()
>>>
>>> Instead of messing around with context->poll_waiting, just look at the
>>> GPollFD to see if the GWakeup needs to be acknowledged.
>>
>> I think this commit contains a typo: "events" should be "revents".
>> (context->wake_up_rec.events is always nonzero at this point in the
>> code, so it makes no sense to test that.) As a result,
>> g_wakeup_acknowledge() is being called much more often than necessary. I
>> think this could easily explain the performance problems that have been
>> reported, but I won't have a chance to test this on my (slow) XP system
>> for a while, and possibly not until tomorrow.
>
>I've confirmed that fixing the typo solves the problem on my XP system. 
>  I suspect that this issue is not specific to XP after all and has more 
>to do with the slowness of the machine, so that the performance problem 
>is more noticeable.  In any case, it's clearly a glib bug.
>
>I've filed a bug report upstream:
>
>   https://bugzilla.gnome.org/show_bug.cgi?id=678052

What incredible perseverence you've shown in tracking this down.  Bravo!

cgf

P.S. I'm relieved and amazed that this didn't boil down to a Cygwin
bug.

--
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