Add init function for bvt scheduler, creating a runqueue and a period
timer, the timer interval is default as 1ms. The interval is the minimum
charging unit.
Tracked-On: #4410
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
BVT (Borrowed virtual time) scheduler is used to schedule vCPUs on pCPU.
It has the concept of virtual time, vCPU with earliset virtual time is
dispatched first.
Main concepts:
tick timer:
a period tick is used to measure the physcial time in units of MCU
(minimum charing unit).
runqueue:
thread in the runqueue is ordered by virtual time.
weight:
each thread receives a share of the pCPU in proportion to its
weight.
context switch allowance:
the physcial time by which the current thread is allowed to advance
beyond the next runnable thread.
warp:
a thread with warp enabled will have a change to minus a value (Wi)
from virtual time to achieve higher priority.
virtual time:
AVT: actual virtual time, advance in proportional to weight.
EVT: effective virtual time.
EVT <- AVT - ( warp ? Wi : 0 )
SVT: scheduler virtual time, the minimum AVT in the runqueue.
Tracked-On: #4410
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
