GNU bug report logs - #34618
26.1.92; timerfd interface causes slowdown on Cygwin

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ken Brown <kbrown <at> cornell.edu>
To: "bug-gnu-emacs <at> gnu.org" <bug-gnu-emacs <at> gnu.org>
Subject: 26.1.92; timerfd interface causes slowdown on Cygwin
Date: Fri, 22 Feb 2019 15:08:33 +0000

[Message part 1 (text/plain, inline)]

Starting with cygwin-3.0.0, Cygwin has the timerfd functions.  But using
them causes Emacs to be very slow to respond to user input.  If I press
a key, there is a 1-2 second delay before Emacs responds.  I'm in the
process of trying to debug this
(http://www.cygwin.org/ml/cygwin/2019-02/msg00364.html).  In the
meantime, the attached patch disables the use of these functions.

OK for the emacs-26 branch (after filling in the bug number)?

Ken

[0001-Disable-the-timerfd-interface-on-Cygwin.patch (text/plain, attachment)]

Message #8 received at 34618 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Ken Brown <kbrown <at> cornell.edu>
Cc: 34618 <at> debbugs.gnu.org
Subject: Re: bug#34618: 26.1.92; timerfd interface causes slowdown on Cygwin
Date: Fri, 22 Feb 2019 18:12:16 +0200

> From: Ken Brown <kbrown <at> cornell.edu>
> Date: Fri, 22 Feb 2019 15:08:33 +0000
> 
> Starting with cygwin-3.0.0, Cygwin has the timerfd functions.  But using
> them causes Emacs to be very slow to respond to user input.  If I press
> a key, there is a 1-2 second delay before Emacs responds.  I'm in the
> process of trying to debug this
> (http://www.cygwin.org/ml/cygwin/2019-02/msg00364.html).  In the
> meantime, the attached patch disables the use of these functions.
> 
> OK for the emacs-26 branch (after filling in the bug number)?

Yes, thanks.

Message #13 received at 34618-done <at> debbugs.gnu.org (full text, mbox):

From: Ken Brown <kbrown <at> cornell.edu>
Cc: "34618-done <at> debbugs.gnu.org" <34618-done <at> debbugs.gnu.org>
Subject: Re: bug#34618: 26.1.92; timerfd interface causes slowdown on Cygwin
Date: Fri, 22 Feb 2019 16:15:18 +0000

Closing.

Message #16 received at 34618 <at> debbugs.gnu.org (full text, mbox):

From: Ken Brown <kbrown <at> cornell.edu>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: "34618 <at> debbugs.gnu.org" <34618 <at> debbugs.gnu.org>
Subject: Re: bug#34618: 26.1.92; timerfd interface causes slowdown on Cygwin
Date: Sat, 9 Mar 2019 19:27:34 +0000

On 2/22/2019 11:12 AM, Eli Zaretskii wrote:
>> From: Ken Brown <kbrown <at> cornell.edu>
>> Date: Fri, 22 Feb 2019 15:08:33 +0000
>>
>> Starting with cygwin-3.0.0, Cygwin has the timerfd functions.  But using
>> them causes Emacs to be very slow to respond to user input.  If I press
>> a key, there is a 1-2 second delay before Emacs responds.  I'm in the
>> process of trying to debug this
>> (http://www.cygwin.org/ml/cygwin/2019-02/msg00364.html).  In the
>> meantime, the attached patch disables the use of these functions.
>>
>> OK for the emacs-26 branch (after filling in the bug number)?
> 
> Yes, thanks.

The Cygwin problems with the timerfd functions have been fixed as of 
cygwin-3.0.2, so I've re-enabled the use of these functions on the master 
branch.  To play it safe, we should probably leave them disabled on the emacs-26 
branch.

Ken

Message #19 received at 34618 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Ken Brown <kbrown <at> cornell.edu>
Cc: 34618 <at> debbugs.gnu.org
Subject: Re: bug#34618: 26.1.92; timerfd interface causes slowdown on Cygwin
Date: Sat, 09 Mar 2019 21:42:38 +0200

> From: Ken Brown <kbrown <at> cornell.edu>
> CC: "34618 <at> debbugs.gnu.org" <34618 <at> debbugs.gnu.org>
> Date: Sat, 9 Mar 2019 19:27:34 +0000
> 
> The Cygwin problems with the timerfd functions have been fixed as of 
> cygwin-3.0.2, so I've re-enabled the use of these functions on the master 
> branch.  To play it safe, we should probably leave them disabled on the emacs-26 
> branch.

Isn't there a way to get at the version of Cygwin at run time?  I
think the best solution is to allow timerfd functions only for
versions whose support is not buggy, and that's not a compile-time
decision, right?

Message #22 received at 34618 <at> debbugs.gnu.org (full text, mbox):

From: Ken Brown <kbrown <at> cornell.edu>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: "34618 <at> debbugs.gnu.org" <34618 <at> debbugs.gnu.org>
Subject: Re: bug#34618: 26.1.92; timerfd interface causes slowdown on Cygwin
Date: Sat, 9 Mar 2019 22:20:44 +0000

[Message part 1 (text/plain, inline)]

On 3/9/2019 2:42 PM, Eli Zaretskii wrote:
>> From: Ken Brown <kbrown <at> cornell.edu>
>> CC: "34618 <at> debbugs.gnu.org" <34618 <at> debbugs.gnu.org>
>> Date: Sat, 9 Mar 2019 19:27:34 +0000
>>
>> The Cygwin problems with the timerfd functions have been fixed as of
>> cygwin-3.0.2, so I've re-enabled the use of these functions on the master
>> branch.  To play it safe, we should probably leave them disabled on the emacs-26
>> branch.
> 
> Isn't there a way to get at the version of Cygwin at run time?  I
> think the best solution is to allow timerfd functions only for
> versions whose support is not buggy, and that's not a compile-time
> decision, right?

Good idea.  How's the attached?

Ken

[0001-Use-a-runtime-test-for-timerfd-on-Cygwin-Bug-34618.patch (text/plain, attachment)]

Message #25 received at 34618 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Ken Brown <kbrown <at> cornell.edu>
Cc: 34618 <at> debbugs.gnu.org
Subject: Re: bug#34618: 26.1.92; timerfd interface causes slowdown on Cygwin
Date: Sun, 10 Mar 2019 05:32:31 +0200

> From: Ken Brown <kbrown <at> cornell.edu>
> CC: "34618 <at> debbugs.gnu.org" <34618 <at> debbugs.gnu.org>
> Date: Sat, 9 Mar 2019 22:20:44 +0000
> 
> > Isn't there a way to get at the version of Cygwin at run time?  I
> > think the best solution is to allow timerfd functions only for
> > versions whose support is not buggy, and that's not a compile-time
> > decision, right?
> 
> Good idea.  How's the attached?

LGTM, thanks.

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