mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-01 02:32:49 -04:00
a5956defe5
Update entry/exit latency and residency time of hikey960 to use more
realistic figures based on unitary tests done on the platform.
The complete results (in us) :
big cluster
cluster CPU
max entry latency 800 400
max exit latency 2900 550
residency 903Mhz 5000 1500
residency 2363Mhz 0 1500
little cluster
cluster CPU
max entry latency 500 400
max exit latency 1600 650
residency 533Mhz 8000 4500
residency 1844Mhz 0 1500
We can see that the residency time depends of the running OPP which is not
handled for now. Then we also have to take into account the constraint of
a residency time shorter than the tick to get full advantage of idle loop
reordering(tick is stopped if idle duration is higher than tick period).
Finally the selected residency value are :
big cluster
cluster CPU
residency 3700 1500
little cluster
cluster CPU
residency 3500 1500
A simple test with a task waking up every 11.111ms shows improvement:
- 5% a lowest OPP
- 22% at highest OPP
The period has been chosen:
- to be shorter than old cluster residency time and longer than new
residency time of cluster off C-state
- to prevent any sync with tick (4ms) when running tests that can add
some variances between tests
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.