From 0d87113080d55cadf72c963f99179a2eb9a282e7 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 24 Oct 2013 19:38:53 +0100 Subject: [PATCH] man: State the negative aspects of TearFree Signed-off-by: Chris Wilson --- man/intel.man | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/man/intel.man b/man/intel.man index d1ec01c..d516449 100644 --- a/man/intel.man +++ b/man/intel.man @@ -136,11 +136,18 @@ Default: use UXA (render acceleration) .TP .BI "Option \*qTearFree\*q \*q" boolean \*q Disable or enable TearFree updates. This option forces X to perform all -rendering to a backbuffer prior to updating the actual display. That update -is then performed synchronously with the vertical refresh of the display so -that the entire update is complete before the display starts its refresh. -That is only one frame is ever visible, preventing an unsightly tear between -two visible differing frames. +rendering to a backbuffer prior to updating the actual display. It requires +an extra memory allocation the same size as a framebuffer, the occasional extra +copy, and requires Damage tracking update. Thus enabling TearFree requires more +memory and is slower (reduced throughput) and introduces a small amount of +output latency, but it should not impact input latency. However, the update to +the screen is then performed synchronously with the vertical refresh of the +display so that the entire update is completed before the display starts its +refresh. That is only one frame is ever visible, preventing an unsightly tear +between two visible and differing frames. Note that this replicates what the +compositing manager should be doing, so it is not advisable to enable both. +However, some compositing managers do cause tearing, and if the outputs are +rotated, there may will still be tearing without TearFree enabled. .IP Default: TearFree is disabled. .TP -- 2.7.4