Lines Matching full:polling

4 The KVM halt polling system
7 The KVM halt polling system provides a feature within KVM whereby the latency
8 of a guest can, under some circumstances, be reduced by polling in the host
14 Polling provides a latency advantage in cases where the guest can be run again
17 dependant. In the event that no wakeup source arrives during the polling
19 invoked. Thus halt polling is especially useful on workloads with very short
20 wakeup periods where the time spent halt polling is minimised and the time
23 The generic halt polling code is implemented in:
31 Halt Polling Interval
35 as the halt polling interval, is increased and decreased based on the perceived
36 effectiveness of the polling in an attempt to limit pointless polling.
47 During polling if a wakeup source is received within the halt polling interval,
49 received during the polling interval (and thus schedule is invoked) there are
50 two options, either the polling interval and total block time[0] were less than
51 the global max polling interval (see module params below), or the total block
52 time was greater than the global max polling interval.
54 In the event that both the polling interval and total block time were less than
55 the global max polling interval then the polling interval can be increased in
56 the hope that next time during the longer polling interval the wake up source
57 will be received while the host is polling and the latency benefits will be
58 received. The polling interval is grown in the function grow_halt_poll_ns() and
62 In the event that the total block time was greater than the global max polling
64 max) to wakeup during the polling interval so it may as well be shrunk in order
65 to avoid pointless polling. The polling interval is shrunk in the function
70 steady state polling interval but will only really do a good job for wakeups
72 adjustment of the polling interval.
75 		      the time between when the halt polling function is
83 polling interval as well as the rate at which the polling interval is grown and
91 |halt_poll_ns		| The global max polling    | KVM_HALT_POLL_NS_DEFAULT|
94 |			| polling interval for      | (per arch value)	      |
98 |			| halt polling interval is  |			      |
109 |			| halt polling interval is  |			      |
129   global max polling interval (halt_poll_ns) then the host will always poll for the
132 - Halt polling essentially presents a trade off between power usage and latency and
137 - Halt polling will only be conducted by the host when no other tasks are runnable on
138   that cpu, otherwise the polling will cease immediately and schedule will be invoked to