[Intel-gfx] [PATCH 3/3] drm/i915: HSW GT3 Slices: Userspace can dynamically forcibly enable all slices

Eric Anholt eric at anholt.net
Tue Oct 15 18:14:33 CEST 2013

Rodrigo Vivi <rodrigo.vivi at gmail.com> writes:

> Rendering buffers that need full GT power can request full power through
> this I915_EXEC_GT_FULL flag. If the default is the power saving with half
> slices off it executes LRIs to immediately enable all slices.

How is userspace supposed to decide that the GPU needs to be at full
power?  Power management is a system problem which wants awareness of
the total load on the GPU from all clients, not just 1.  The kernel can
get that information, but userspace can't.

Basically, if you give userspace this knob, userspace will just have to
set it on every batchbuffer.  At which point, why give them the knob at
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