Lines Matching full:cpus
19 2. Omit scheduling-clock ticks on idle CPUs (CONFIG_NO_HZ_IDLE=y or
23 3. Omit scheduling-clock ticks on CPUs that are either idle or that
65 Omit Scheduling-Clock Ticks For Idle CPUs
74 scheduling-clock interrupts to idle CPUs, which is critically important
82 idle CPUs. That said, dyntick-idle mode is not free:
104 Omit Scheduling-Clock Ticks For CPUs With Only One Runnable Task
109 Note that omitting scheduling-clock ticks for CPUs with only one runnable
110 task implies also omitting them for idle CPUs.
113 sending scheduling-clock interrupts to CPUs with a single runnable task,
114 and such CPUs are said to be "adaptive-ticks CPUs". This is important
119 delayed during a given iteration, all the other CPUs will be forced to
121 by one less than the number of CPUs. In these situations, there is
125 boot parameter specifies the adaptive-ticks CPUs. For example,
126 "nohz_full=1,6-8" says that CPUs 1, 6, 7, and 8 are to be adaptive-ticks
127 CPUs. Note that you are prohibited from marking all of the CPUs as
128 adaptive-tick CPUs: At least one non-adaptive-tick CPU must remain
130 calls like gettimeofday() returns accurate values on adaptive-tick CPUs.
136 this means that your system must have at least two CPUs in order for
139 Finally, adaptive-ticks CPUs must have their RCU callbacks offloaded.
159 3. POSIX CPU timers prevent CPUs from entering adaptive-tick mode.
167 preventing CPUs with large numbers of perf events pending from
170 5. Scheduler statistics for adaptive-tick CPUs may be computed
171 slightly differently than those for non-adaptive-tick CPUs.
183 There are situations in which idle CPUs cannot be permitted to
187 The CONFIG_RCU_FAST_NO_HZ=y Kconfig option may be used to cause such CPUs
189 a timer will awaken these CPUs every four jiffies in order to ensure
193 using the CONFIG_RCU_NOCB_CPU=y Kconfig option. The specific CPUs to
195 which takes a comma-separated list of CPUs and CPU ranges, for example,
196 "1,3-5" selects CPUs 1, 3, 4, and 5.
198 The offloaded CPUs will never queue RCU callbacks, and therefore RCU
199 never prevents offloaded CPUs from entering either dyntick-idle mode
201 pin the "rcuo" kthreads to specific CPUs if desired. Otherwise, the
225 Note: this test requires that your system have at least two CPUs.
255 CPUs, which can significantly reduce maximum performance.
273 nevertheless sends scheduling-clock interrupts to CPUs having a
289 simply offloading RCU callbacks from all CPUs and pinning them
295 interrupts and tasks to particular CPUs.
308 * Unless all CPUs are idle, at least one CPU must keep the
312 * If there might potentially be some adaptive-ticks CPUs, there
314 going, even if all CPUs are otherwise idle.