Sometimes your system may display a message indicating that the linux kernel is in the process of freezing. There can be several reasons for this problem.
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2007 Rafael J. Wysocki
Me. What Is Task Freezing?¶
Task freezing is a mechanism that is also required by user-space processes and other processes.Kernel threads are checked during sleep, or it could be a system-wide suspend (on somearchitecture).
II.How Is This Done?¶
There are three exercise flags for this task: PF_NOFREEZE, PF_FROZEN.and PF_FREEZER_SKIP (last sub). Tasks thatPF_NOFREEZE is not defined as friendly (all space and process some kernel threads).considered AND “frozen” Fixed in a special way before the system enters the systemA suspended state is also created, as extreme as a hibernation image (hereinafterwe only recognize hibernation, but the description can also be Paused).
Namely as the first function of the process hibernation procedureFreeze_processes() a (defined in kernel/power/process.c). System 1 for scalingThe system_freezing_cnt variable (as opposed to each task’s indicator) is used to displaywhether the system should check the freezing process. And freezing_processes()define my variable. After that, it executes the try_to_freeze_tasks() function, which sendsfalse signal to make sure you start all processes in user space and enable all kernel threads. frozenall should constructs react to this when calling try_to_freeze(), whichresults in a double call to __refrigerator() (defined in kernel/freezer in.c), usually definesthe task’s PF_FROZEN flag toggles one state and makes TASK_UNINTERRUPTIBLEimage until PF_FROZEN is cleared to do so. Then we say that there is an end”frozen” and therefore undoubtedly the composition is mentioned with the functions that control this mechanismto “als Frieza” (these functions are usually defined in kernel/power/process.c,kernel/freezer.c and include/linux/freezer.h). User space processes usuallyFreeze before the main topics. Shouldn’t
__refrigerator() is called correctly. Use his checks insteadtry_to_freeze() function In (define include/linux/freezer.what h)if the refrigerator needs to be frozen and the task deserves __refrigerator() enter.
For Wearer space processes, try_to_freeze() is automatically called fromSignal handling code, but it needs to be called from Freezable core clothesappear explicitly in the appropriate places or use
wait_event_freezeable() orwait_event_freezeable_timeout() macros (defined in include/linux/freezer.h)this pack of intermittent sleep with a check task to freeze acceptance and beCall try_to_freeze(). The main Freezable kernel thread loop might look like thisas follows:
set_freezeable();do hub_events(); wait_event_freezeable(khubd_wait, !list_empty(&hub_event_list) while (!kthread_should_stop() !list_empty(&hub_event_list));
(from || drivers/usb/core/hub.c::hub_thread()).
If the Freezable core fails, try_to_freeze() should be called after the Freezer operation.launched one, the task freezes and the whole thing failsThere is an arrested hibernation. That’s why the core can be frozenThreads call try somewhere_to_freeze() or something to useMacros and
After that, this state of system memory was restored from a dream image of a terrible anddevices have been reset, the thaw_processes() task is calledto clear the PF_FROZEN flag type for each frozen procedure. SoIf you have frozen tasks, exit __refrigerator() and start executing.
Basic Principle Of Functions Related To Ice Cream Making And Defrosting Tasks¶
freeze only userspace tasks
freeze all tasks (including cores), threads because we can’t freezeKernel threads should freeze user-space tasks
unfreeze only kernel threads; this is especially useful when you need to doanything special related to thawing of the center wire and similar to thawinguserspace tasks or when we ask for a delay in the release of userspace tasks
unfreeze all tasks (including kernel threads) if we can not unfreeze user spaceTasks to always unfreeze kernel threads
III. What Basic Clothes Can Be Frozen?¶
It’s not nice to be kernel threads – Freezable by default. However, the wire core may come loose.pf_nofreeze itself by calling set_freezable() (by resetting PF_NOFREEZEcan’t live). At this point, he is considered almost frozen.and should place the appropriate call in the try_to_freeze() function.
IV. Why Are We Doing This?¶
In general, there are several reasons to use freezing tasks:Get this software now and start surfing the web worry-free.