Bug 106405

Summary:	[Regression 1.12->1.13] "read from connection when polling" causes video to freeze
Product:	XCB	Reporter:	John Lindgren <john>
Component:	Library	Assignee:	xcb mailing list dummy <xcb>
Status:	RESOLVED MOVED	QA Contact:	xcb mailing list dummy <xcb>
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description John Lindgren 2018-05-05 04:22:57 UTC

After updating libxcb to 1.13, video intermittently freezes in Skype calls.  Actually, it's not just the video stream that hangs, the whole Skype window freezes temporarily (1-10 seconds).  Switching in/out of fullscreen gets things moving again.

The hangs are most noticeable in Skype (which is Chromium-based) but also occur occasionally in Chromium itself; I have seen brief but definite freezes/stutters in YouTube and Netflix video, as well as scrolling through at least some web pages (amazon.com for example).

Reverting the following commit makes everything smooth again:
https://cgit.freedesktop.org/xcb/libxcb/commit/?id=fad81b63422105f9345215ab2716c4b804ec7986

Since Skype and Chromium share the same codebase, and I haven't seen freezes in other applications, it could be a bug in Chromium that is merely triggered by the libxcb change.  I don't know enough of the internals of either project to say which is at fault.

Disabling compositing (compton) seemed to work around the issue but of course leads video tearing, which is no less annoying.

Arch Linux x86_64 w/ kernel 4.16.5-1
Intel (Skylake) graphics w/ modesetting driver + DRI2
Xorg 1.19.6+13+gd0d1a694f-2
Mesa 18.0.1-1
Compton 0.1_beta2.5-10 w/ GLX backend

Comment 1 GitLab Migration User 2019-02-16 19:41:02 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/lib/libxcb/issues/19.

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