Bug 7911 - Keyboard and mouse input has long pauses after XDCMP login
Summary: Keyboard and mouse input has long pauses after XDCMP login
Alias: None
Product: xorg
Classification: Unclassified
Component: Server/DDX/Xwin (show other bugs)
Version: (6.9 RC1)
Hardware: x86 (IA32) Windows (All)
: high major
Assignee: Xorg Project Team
QA Contact: Xorg Project Team
Whiteboard: 2011BRB_Reviewed
Keywords: NEEDINFO
Depends on:
Blocks: 18093
  Show dependency treegraph
Reported: 2006-08-18 00:46 UTC by Vince Negri
Modified: 2018-12-13 18:31 UTC (History)
3 users (show)

See Also:
i915 platform:
i915 features:


Description Vince Negri 2006-08-18 00:46:37 UTC
Client system : Windows 2000 service pack 4 with all updates as of 2006.08.14
Linux server is SuSE Linux Pro 10.0 (fully patched)

Basic symptoms after logging in over XDCMP as any normal user: everything fine
until I press a key, then longish (about a second) pauses on both mouse and key
input. No CPU usage spikes on either server or client machine, so it appears
that something is waiting for an event (that it shouldn't be) and timing out.

No problems with the previous release 6.8.2 version of Cygwin/X.

Colin Harrison <colin dot harrison at virgin dot net> reported that this patch
fixed the delays, but stopped key repeat working:

--- ./programs/Xserver/os/save_xdmcp.c  2006-07-30 11:56:30.000000000 +0100
+++ ./programs/Xserver/os/xdmcp.c       2006-07-30 13:49:09.000000000 +0100
@@ -721,7 +721,7 @@
                keepaliveDormancy = defaultKeepaliveDormancy;
        if (XFD_ANYSET(&AllClients) && state == XDM_RUN_SESSION)
-           timeOutTime = GetTimeInMillis() +  keepaliveDormancy * 1000;
+           timeOutTime = 1;
     else if (timeOutTime && (int) (GetTimeInMillis() - timeOutTime) >= 0)
Comment 1 Colin Harrison 2006-08-18 04:35:23 UTC
I now use a different patch in Xming (needs refining for X.Org use and the 
keyrepeat problem is not an issue). I haven't a really solid explanation as to 
why it works, but it works well!

--- ./programs/Xserver/os/save_xdmcp.c  2006-07-30 18:18:48.000000000 +0100
+++ ./programs/Xserver/os/xdmcp.c       2006-07-30 18:41:24.000000000 +0100
@@ -720,10 +720,12 @@
            else if (state == XDM_RUN_SESSION)
                keepaliveDormancy = defaultKeepaliveDormancy;
-       if (XFD_ANYSET(&AllClients) && state == XDM_RUN_SESSION)
+       if (0)
+       /*if (XFD_ANYSET(&AllClients) && state == XDM_RUN_SESSION)*/
            timeOutTime = GetTimeInMillis() +  keepaliveDormancy * 1000;
-    else if (timeOutTime && (int) (GetTimeInMillis() - timeOutTime) >= 0)
+    else if (0)
+    /*else if (timeOutTime && (int) (GetTimeInMillis() - timeOutTime) >= 0)*/
        if (state == XDM_RUN_SESSION)
Comment 2 Colin Harrison 2006-08-19 00:40:59 UTC
More background:-
There can be annoying keyboard latency in XDMCP mode with heavyweight display 
managers, like KDM (this bug appeared in Cygwin/X and was always in 
Xming). When Cygwin/X 'caught' the bug I knew a fix in Xming was feasible so 
traced it to part of the XMDCP state machine. The bug can be user sensitive, 
coming and going as different accounts are accessed. I've looked in detail at 
the code versions but have been unable, so far, to trace where it came from.
Comment 3 Rob Currey 2006-09-27 14:59:29 UTC
I wonder if this isn't yet another symptom of a problem I described here ...

my favorite description also follows from this link ... 

xdmcp.c is broken ... just not sure I can definately say how or why yet ...
Comment 4 Colin Harrison 2007-01-30 04:55:47 UTC
This one has too high a Priority and Severity. It only affects Windows OS's.
No one currently maintains for Cygwin/X, so a fix cannot be tried and tested there.
I maintain for Xming and my patch works for it, but it is very empirical, and so not for general consumption. I just want to sit on this and wait and see if other DDX's have trouble with xdmcp too.
Comment 5 Daniel Stone 2007-02-27 01:33:13 UTC
Sorry about the phenomenal bug spam, guys.  Adding xorg-team@ to the QA contact so bugs don't get lost in future.
Comment 6 Yaakov Selkowitz 2010-03-23 03:44:27 UTC
Is this bug still relevant?
Comment 7 Colin Harrison 2010-03-23 05:40:12 UTC
Last time I didn't apply the patch from this Bugzilla to Xming I got this fault reported again. Hopefully XDMCP will go away soon..it's unsafe, old and not very IPv6 friendly!
Comment 8 GitLab Migration User 2018-12-13 18:31:24 UTC
-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/xorg/xserver/issues/196.

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