diff options
Diffstat (limited to 'Documentation/cpu-hotplug.txt')
-rw-r--r-- | Documentation/cpu-hotplug.txt | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index cc60d29b954c..b6d24c22274b 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt | |||
@@ -217,14 +217,17 @@ Q: What happens when a CPU is being logically offlined? | |||
217 | A: The following happen, listed in no particular order :-) | 217 | A: The following happen, listed in no particular order :-) |
218 | 218 | ||
219 | - A notification is sent to in-kernel registered modules by sending an event | 219 | - A notification is sent to in-kernel registered modules by sending an event |
220 | CPU_DOWN_PREPARE | 220 | CPU_DOWN_PREPARE or CPU_DOWN_PREPARE_FROZEN, depending on whether or not the |
221 | CPU is being offlined while tasks are frozen due to a suspend operation in | ||
222 | progress | ||
221 | - All process is migrated away from this outgoing CPU to a new CPU | 223 | - All process is migrated away from this outgoing CPU to a new CPU |
222 | - All interrupts targeted to this CPU is migrated to a new CPU | 224 | - All interrupts targeted to this CPU is migrated to a new CPU |
223 | - timers/bottom half/task lets are also migrated to a new CPU | 225 | - timers/bottom half/task lets are also migrated to a new CPU |
224 | - Once all services are migrated, kernel calls an arch specific routine | 226 | - Once all services are migrated, kernel calls an arch specific routine |
225 | __cpu_disable() to perform arch specific cleanup. | 227 | __cpu_disable() to perform arch specific cleanup. |
226 | - Once this is successful, an event for successful cleanup is sent by an event | 228 | - Once this is successful, an event for successful cleanup is sent by an event |
227 | CPU_DEAD. | 229 | CPU_DEAD (or CPU_DEAD_FROZEN if tasks are frozen due to a suspend while the |
230 | CPU is being offlined). | ||
228 | 231 | ||
229 | "It is expected that each service cleans up when the CPU_DOWN_PREPARE | 232 | "It is expected that each service cleans up when the CPU_DOWN_PREPARE |
230 | notifier is called, when CPU_DEAD is called its expected there is nothing | 233 | notifier is called, when CPU_DEAD is called its expected there is nothing |
@@ -242,9 +245,11 @@ A: This is what you would need in your kernel code to receive notifications. | |||
242 | 245 | ||
243 | switch (action) { | 246 | switch (action) { |
244 | case CPU_ONLINE: | 247 | case CPU_ONLINE: |
248 | case CPU_ONLINE_FROZEN: | ||
245 | foobar_online_action(cpu); | 249 | foobar_online_action(cpu); |
246 | break; | 250 | break; |
247 | case CPU_DEAD: | 251 | case CPU_DEAD: |
252 | case CPU_DEAD_FROZEN: | ||
248 | foobar_dead_action(cpu); | 253 | foobar_dead_action(cpu); |
249 | break; | 254 | break; |
250 | } | 255 | } |