[Mesa-dev] i965: L3 cache partitioning.

[Francisco Jerez]

This series implements dynamic partitioning of the L3 cache space
among its clients, the purpose is multiple:

 - Steal a chunk of L3 space when necessary and reserve it for SLM as
   required to support compute shaders with shared variables.

 - Allow L3 caching of dataport DC memory access where the default L3
   partitioning doesn't have any space reserved for it (pre-Gen8) --
   Should improve performance of scratch access (register spills and
   fills and some forms of indirect array indexing), atomic counters
   and images.

 - Allow dynamic changes of the L3 configuration for work-loads that
   could benefit from a partitioning other than the default
   (e.g. reduce URB size to gain some additional cache space on
   heavily fragment-bound workloads, or split the L3 allocation of
   different clients to reduce thrashing).  The basic infrastructure
   to achieve this is implemented here but no specific heuristics are
   included yet in this series.

The series can be found here in a testable form:
http://cgit.freedesktop.org/~currojerez/mesa/log/?h=i965-l3-partitioning

[PATCH 01/13] i965: Define symbolic constants for some useful L3 cache control registers.
[PATCH 02/13] i965: Keep track of whether LRI is allowed in the context struct.
[PATCH 03/13] i965: Define state flag to signal that the URB size has been altered.
[PATCH 04/13] i965/gen8: Don't add workaround bits to PIPE_CONTROL stalls if DC flush is set.
[PATCH 05/13] i965: Import tables enumerating the set of validated L3 configurations.
[PATCH 06/13] i965: Implement programming of the L3 configuration.
[PATCH 07/13] i965/hsw: Enable L3 atomics.
[PATCH 08/13] i965: Implement selection of the closest L3 configuration based on a vector of weights.
[PATCH 09/13] i965: Calculate appropriate L3 partition weights for the current pipeline state.
[PATCH 10/13] i965: Implement L3 state atom.
[PATCH 11/13] i965: Add debug flag to print out the new L3 state during transitions.
[PATCH 12/13] i965: Work around L3 state leaks during context switches.
[PATCH 13/13] i965: Hook up L3 partitioning state atom.