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linux-nvgpu/drivers/gpu
Konsta Holtta 0fbc1a2652 gpu: nvgpu: avoid recursion in runlist construction
MISRA rule 17.2 forbids recursion as a hazard on the stack space. To
comply and additionally to make the code somewhat more straightforward
to read, rewrite the runlist construction with three explicit functions
that work as the three levels of the earlier recursion. These levels map
to the three priority levels of TSGs and having more than that is
unlikely.

When "runlist interleaving" is enabled, TSGs with higher priorities get
interleaved between the switch of each pair of lower-level priority
TSGs, so that the latency for a job at priority level X is no more than
all jobs' timeslices of priority X and higher, plus at most one job at a
lower level.

This can be illustrated as follows (low, medium, high TSGs 1 and 2):

L1 L2 (only low-priority TSGs)
H1 H2 (only high-priority TSGs)
H1 H2 M1 H1 H2 M2 (no low-priority TSGs)
M1 M2 L1 M1 M2 L2 (no high-priority TSGs)
H1 H2 L1 H1 H2 L2 (no medium-priority TSGs)
H1 H2 M1 H1 H2 M2 H1 H2 L1 H1 H2 M1 H1 H2 M2 H1 H2 L2 (no empty levels)

Without interleaving, the items are simply grouped by priority.

Jira NVGPU-1174

Change-Id: Ic3b5106945df7105633730ecd1d150af770a5e83
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1918226
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
2018-10-26 11:14:19 -07:00
..
2017-10-29 11:00:55 -07:00