Since upstream commit 715f7f9ece ("locking/rtmutex: Squash !RT
tasks to DEFAULT_PRIO"), non-rt tasks do not inherit the
nice-priority values across rt_mutexes. This removes the minor
(and indirect) priority-inheritance that rt-mutexes provided for
CFS tasks.
Though without priority inheritance, time-bounded priority
inversion can occur between CFS tasks of different nice
priorities / cgroup limitations. The proxy-execution efforts
are a work-in-progress to resolve this upstream, but in the
meantime it is left to vendor hooks to provide a near term
solution to avoid priority inversion between CFS tasks.
In our oem scheduler, if a CFS thread has an "user-aware
property", we will always pick it even if it's vruntime is
bigger than the smallest one in runqueue. That's why the
trace_android_rvh_replace_next_task_fair vendorhook was added
previously in commit 53e809978443 ("ANDROID: vendor_hooks: Add
hooks for scheduler").
Thus for our oem scheduler, important CFS tasks(like
RenderThread) are marked with the "user-aware property" in their
struct task_struct. If those tasks are blocked on an rtmutex, we
want to allow the "user-aware property" to be inherited to lock
owner, so it will be selected to run immediately to release the
lock.
To support this, we need new hooks to map "user-aware property"
into different rtmutex_waiter prio and update the owner's
"user-aware property" if needed. Thus these additional vendor
hooks are needed.
In the future, once an generalized upstream solution for CFS
priority inheritance is in place, this will no longer be needed.
Bug: 290585456
Change-Id: I6521ed2086b147400a54da6b84a324baf16bc649
Signed-off-by: xieliujie <xieliujie@oppo.com>
544ae28cf6