Messages in this thread | | | From | Joel Fernandes <> | Date | Thu, 29 Jun 2017 17:19:14 -0700 | Subject | wake_wide mechanism clarification |
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Dear Mike,
I wanted your kind help to understand your patch "sched: beef up wake_wide()"[1] which is a modification to the original patch from Michael Wang [2].
In particular, I didn't following the following comment: " to shared cache, we look for a minimum 'flip' frequency of llc_size in one partner, and a factor of lls_size higher frequency in the other."
Why are wanting the master's flip frequency to be higher than the slaves by the factor?
The code here is written as:
if (slave < factor || master < slave * factor) return 0;
However I think we should just do (with my current and probably wrong understanding):
if (slave < factor || master < factor) return 0;
Basically, I didn't follow why we multiply the slave's flips with llc_size. That makes it sound like the master has to have way more flips than the slave to return 0 from wake_wide. Could you maybe give an example to clarify? Thanks a lot for your help,
I am also CC'ing Peter and some ARM folks for the discussion (and also Jocef who was discuss it with Mike on the mailing list few years ago).
Thanks, Joel
[1] https://patchwork.kernel.org/patch/6787941/ [2] https://lkml.org/lkml/2013/7/4/20
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