#, fuzzy msgid "" msgstr "" "Project-Id-Version: man-pages-l10n VERSION\n" "POT-Creation-Date: 2014-07-17 17:57+0900\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" #. type: TH #: man-pages/man7/sched.7:32 #, no-wrap msgid "SCHED" msgstr "" #. type: TH #: man-pages/man7/sched.7:32 #, no-wrap msgid "2014-07-08" msgstr "" #. type: TH #: man-pages/man7/sched.7:32 #, no-wrap msgid "Linux" msgstr "" #. type: TH #: man-pages/man7/sched.7:32 #, no-wrap msgid "Linux Programmer's Manual" msgstr "" #. type: SH #: man-pages/man7/sched.7:33 #, no-wrap msgid "NAME" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:35 msgid "sched - overview of scheduling APIs" msgstr "" #. type: SH #: man-pages/man7/sched.7:35 #, no-wrap msgid "DESCRIPTION" msgstr "" #. type: SS #: man-pages/man7/sched.7:36 #, no-wrap msgid "API summary" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:38 msgid "The Linux scheduling APIs are as follows:" msgstr "" #. type: TP #: man-pages/man7/sched.7:38 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:41 msgid "Set the scheduling policy and parameters of a specified thread." msgstr "" #. type: TP #: man-pages/man7/sched.7:41 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:44 msgid "Return the scheduling policy of a specified thread." msgstr "" #. type: TP #: man-pages/man7/sched.7:44 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:47 msgid "Set the scheduling parameters of a specified thread." msgstr "" #. type: TP #: man-pages/man7/sched.7:47 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:50 msgid "Fetch the scheduling parameters of a specified thread." msgstr "" #. type: TP #: man-pages/man7/sched.7:50 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:53 msgid "" "Return the minimum priority available in a specified scheduling policy." msgstr "" #. type: TP #: man-pages/man7/sched.7:53 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:56 msgid "" "Return the maximum priority available in a specified scheduling policy." msgstr "" #. type: TP #: man-pages/man7/sched.7:56 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:60 msgid "" "Fetch the quantum used for threads that are scheduled under the \"round-" "robin\" scheduling policy." msgstr "" #. type: TP #: man-pages/man7/sched.7:60 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:64 msgid "" "Cause the caller to relinquish the CPU, so that some other thread be " "executed." msgstr "" #. type: TP #: man-pages/man7/sched.7:64 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:68 msgid "(Linux-specific) Set the CPU affinity of a specified thread." msgstr "" #. type: TP #: man-pages/man7/sched.7:68 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:72 msgid "(Linux-specific) Get the CPU affinity of a specified thread." msgstr "" #. type: TP #: man-pages/man7/sched.7:72 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:79 msgid "" "Set the scheduling policy and parameters of a specified thread. This (Linux-" "specific) system call provides a superset of the functionality of " "B(2) and B(2)." msgstr "" #. type: TP #: man-pages/man7/sched.7:79 #, no-wrap msgid "B(2)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:87 msgid "" "Fetch the scheduling policy and parameters of a specified thread. This " "(Linux-specific) system call provides a superset of the functionality of " "B(2) and B(2)." msgstr "" #. type: SS #: man-pages/man7/sched.7:87 #, no-wrap msgid "Scheduling policies" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:95 msgid "" "The scheduler is the kernel component that decides which runnable thread " "will be executed by the CPU next. Each thread has an associated scheduling " "policy and a I scheduling priority, I. The " "scheduler makes its decisions based on knowledge of the scheduling policy " "and static priority of all threads on the system." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:100 msgid "" "For threads scheduled under one of the normal scheduling policies " "(B, B, B), I is not " "used in scheduling decisions (it must be specified as 0)." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:114 msgid "" "Processes scheduled under one of the real-time policies (B, " "B) have a I value in the range 1 (low) to 99 " "(high). (As the numbers imply, real-time threads always have higher " "priority than normal threads.) Note well: POSIX.1-2001 requires an " "implementation to support only a minimum 32 distinct priority levels for the " "real-time policies, and some systems supply just this minimum. Portable " "programs should use B(2) and " "B(2) to find the range of priorities supported for " "a particular policy." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:120 msgid "" "Conceptually, the scheduler maintains a list of runnable threads for each " "possible I value. In order to determine which thread runs " "next, the scheduler looks for the nonempty list with the highest static " "priority and selects the thread at the head of this list." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:124 msgid "" "A thread's scheduling policy determines where it will be inserted into the " "list of threads with equal static priority and how it will move inside this " "list." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:132 msgid "" "All scheduling is preemptive: if a thread with a higher static priority " "becomes ready to run, the currently running thread will be preempted and " "returned to the wait list for its static priority level. The scheduling " "policy determines the ordering only within the list of runnable threads with " "equal static priority." msgstr "" #. type: SS #: man-pages/man7/sched.7:132 #, no-wrap msgid "SCHED_FIFO: First in-first out scheduling" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:141 msgid "" "B can be used only with static priorities higher than 0, which " "means that when a B threads becomes runnable, it will always " "immediately preempt any currently running B, B, or " "B thread. B is a simple scheduling algorithm " "without time slicing. For threads scheduled under the B policy, " "the following rules apply:" msgstr "" #. type: IP #: man-pages/man7/sched.7:141 man-pages/man7/sched.7:146 man-pages/man7/sched.7:149 man-pages/man7/sched.7:164 man-pages/man7/sched.7:413 man-pages/man7/sched.7:422 man-pages/man7/sched.7:445 man-pages/man7/sched.7:453 man-pages/man7/sched.7:492 man-pages/man7/sched.7:500 man-pages/man7/sched.7:505 man-pages/man7/sched.7:510 #, no-wrap msgid "*" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:146 msgid "" "A B thread that has been preempted by another thread of higher " "priority will stay at the head of the list for its priority and will resume " "execution as soon as all threads of higher priority are blocked again." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:149 msgid "" "When a B thread becomes runnable, it will be inserted at the end " "of the list for its priority." msgstr "" #. In 2.2.x and 2.4.x, the thread is placed at the front of the queue #. In 2.0.x, the Right Thing happened: the thread went to the back -- MTK #. type: Plain text #: man-pages/man7/sched.7:164 msgid "" "A call to B(2), B(2), or " "B(2) will put the B (or B) thread " "identified by I at the start of the list if it was runnable. As a " "consequence, it may preempt the currently running thread if it has the same " "priority. (POSIX.1-2001 specifies that the thread should go to the end of " "the list.)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:168 msgid "" "A thread calling B(2) will be put at the end of the list." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:172 msgid "" "No other events will move a thread scheduled under the B policy " "in the wait list of runnable threads with equal static priority." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:177 msgid "" "A B thread runs until either it is blocked by an I/O request, it " "is preempted by a higher priority thread, or it calls B(2)." msgstr "" #. type: SS #: man-pages/man7/sched.7:177 #, no-wrap msgid "SCHED_RR: Round-robin scheduling" msgstr "" #. On Linux 2.4, the length of the RR interval is influenced #. by the process nice value -- MTK #. type: Plain text #: man-pages/man7/sched.7:196 msgid "" "B is a simple enhancement of B. Everything described " "above for B also applies to B, except that each thread " "is allowed to run only for a maximum time quantum. If a B thread " "has been running for a time period equal to or longer than the time quantum, " "it will be put at the end of the list for its priority. A B " "thread that has been preempted by a higher priority thread and subsequently " "resumes execution as a running thread will complete the unexpired portion of " "its round-robin time quantum. The length of the time quantum can be " "retrieved using B(2)." msgstr "" #. type: SS #: man-pages/man7/sched.7:196 #, no-wrap msgid "SCHED_DEADLINE: Sporadic task model deadline scheduling" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:208 msgid "" "Since version 3.14, Linux provides a deadline scheduling policy " "(B). This policy is currently implemented using GEDF " "(Global Earliest Deadline First) in conjunction with CBS (Constant " "Bandwidth Server). To set and fetch this policy and associated attributes, " "one must use the Linux-specific B(2) and B(2) " " system calls." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:226 msgid "" "A sporadic task is one that has a sequence of jobs, where each job is " "activated at most once per period. Each job also has a I, before which it should finish execution, and a I, which is the CPU time necessary for executing the job. The moment " "when a task wakes up because a new job has to be executed is called the " "I (also referred to as the request time or release time). The " "I is the time at which a task starts its execution. The " "I is thus obtained by adding the relative deadline to the " "arrival time." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:228 msgid "The following diagram clarifies these terms:" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:239 #, no-wrap msgid "" "arrival/wakeup absolute deadline\n" " | start time |\n" " | | |\n" " v v v\n" "-----x--------xooooooooooooooooo--------x--------x---\n" " |E- comp. time -E|\n" " |E------- relative deadline ------E|\n" " |E-------------- period -------------------E|\n" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:258 msgid "" "When setting a B policy for a thread using " "B(2), one can specify three parameters: I, " "I, and I. These parameters do not necessarily correspond " "to the aforementioned terms: usual practice is to set Runtime to something " "bigger than the average computation time (or worst-case execution time for " "hard real-time tasks), Deadline to the relative deadline, and Period to the " "period of the task. Thus, for B scheduling, we have:" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:269 #, no-wrap msgid "" "arrival/wakeup absolute deadline\n" " | start time |\n" " | | |\n" " v v v\n" "-----x--------xooooooooooooooooo--------x--------x---\n" " |E-- Runtime -------E|\n" " |E----------- Deadline -----------E|\n" " |E-------------- Period -------------------E|\n" msgstr "" #. FIXME It looks as though specifying sched_period as 0 means #. "make sched_period the same as sched_deadline", right? #. This needs to be documented. #. type: Plain text #: man-pages/man7/sched.7:289 msgid "" "The three deadline-scheduling parameters correspond to the I, " "I, and I fields of the I " "structure; see B(2). These fields express value in " "nanoseconds. If I is specified as 0, then it is made the same " "as I." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:291 msgid "The kernel requires that:" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:293 #, no-wrap msgid " sched_runtime E= sched_deadline E= sched_period\n" msgstr "" #. See __checkparam_dl in kernel/sched/core.c #. type: Plain text #: man-pages/man7/sched.7:303 msgid "" "In addition, under the current implementation, all of the parameter values " "must be at least 1024 (i.e., just over one microsecond, which is the " "resolution of the implementation), and less than 2^63. If any of these " "checks fails, B(2) fails with the error B." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:306 msgid "" "The CBS guarantees non-interference between tasks, by throttling threads " "that attempt to over-run their specified Runtime." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:319 msgid "" "To ensure deadline scheduling guarantees, the kernel must prevent situations " "where the set of B threads is not feasible (schedulable) " "within the given constraints. The kernel thus performs an admittance test " "when setting or changing B policy and attributes. This " "admission test calculates whether the change is feasible; if it is not " "B(2) fails with the error B." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:325 msgid "" "For example, it is required (but not necessarily sufficient) for the total " "utilization to be less than or equal to the total number of CPUs available, " "where, since each thread can maximally run for Runtime per Period, that " "thread's utilization is its Runtime divided by its Period." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:336 msgid "" "In order to fulfil the guarantees that are made when a thread is admitted to " "the B policy, B threads are the highest " "priority (user controllable) threads in the system; if any B " "thread is runnable, it will preempt any thread scheduled under one of the " "other policies." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:344 msgid "" "A call to B(2) by a thread scheduled under the B " "policy will fail with the error B, unless the thread has its reset-" "on-fork flag set (see below)." msgstr "" #. FIXME Calling sched_getparam() on a SCHED_DEADLINE thread #. fails with EINVAL, but sched_getscheduler() succeeds. #. Is that intended? (Why?) #. type: Plain text #: man-pages/man7/sched.7:356 msgid "" "A B thread that calls B(2) will yield the " "current job and wait for a new period to begin." msgstr "" #. type: SS #: man-pages/man7/sched.7:356 #, no-wrap msgid "SCHED_OTHER: Default Linux time-sharing scheduling" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:373 msgid "" "B can be used at only static priority 0. B is the " "standard Linux time-sharing scheduler that is intended for all threads that " "do not require the special real-time mechanisms. The thread to run is " "chosen from the static priority 0 list based on a I priority that " "is determined only inside this list. The dynamic priority is based on the " "nice value (set by B(2), B(2), or B(2)) " "and increased for each time quantum the thread is ready to run, but denied " "to run by the scheduler. This ensures fair progress among all " "B threads." msgstr "" #. type: SS #: man-pages/man7/sched.7:373 #, no-wrap msgid "SCHED_BATCH: Scheduling batch processes" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:385 msgid "" "(Since Linux 2.6.16.) B can be used only at static priority 0. " " This policy is similar to B in that it schedules the thread " "according to its dynamic priority (based on the nice value). The difference " "is that this policy will cause the scheduler to always assume that the " "thread is CPU-intensive. Consequently, the scheduler will apply a small " "scheduling penalty with respect to wakeup behavior, so that this thread is " "mildly disfavored in scheduling decisions." msgstr "" #. The following paragraph is drawn largely from the text that #. accompanied Ingo Molnar's patch for the implementation of #. SCHED_BATCH. #. commit b0a9499c3dd50d333e2aedb7e894873c58da3785 #. type: Plain text #: man-pages/man7/sched.7:395 msgid "" "This policy is useful for workloads that are noninteractive, but do not want " "to lower their nice value, and for workloads that want a deterministic " "scheduling policy without interactivity causing extra preemptions (between " "the workload's tasks)." msgstr "" #. type: SS #: man-pages/man7/sched.7:395 #, no-wrap msgid "SCHED_IDLE: Scheduling very low priority jobs" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:399 msgid "" "(Since Linux 2.6.23.) B can be used only at static priority 0; " "the process nice value has no influence for this policy." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:407 msgid "" "This policy is intended for running jobs at extremely low priority (lower " "even than a +19 nice value with the B or B " "policies)." msgstr "" #. type: SS #: man-pages/man7/sched.7:407 #, no-wrap msgid "Resetting scheduling policy for child processes" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:413 msgid "" "Each thread has a reset-on-fork scheduling flag. When this flag is set, " "children created by B(2) do not inherit privileged scheduling " "policies. The reset-on-fork flag can be set by either:" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:422 msgid "" "ORing the B flag into the I argument when " "calling B(2) (since Linux 2.6.32); or" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:429 msgid "" "specifying the B flag in I when " "calling B(2)." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:435 msgid "" "Note that the constants used with these two APIs have different names. The " "state of the reset-on-fork flag can analogously be retrieved using " "B(2) and B(2)." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:442 msgid "" "The reset-on-fork feature is intended for media-playback applications, and " "can be used to prevent applications evading the B resource " "limit (see B(2)) by creating multiple child processes." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:445 msgid "" "More precisely, if the reset-on-fork flag is set, the following rules apply " "for subsequently created children:" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:453 msgid "" "If the calling thread has a scheduling policy of B or " "B, the policy is reset to B in child processes." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:456 msgid "" "If the calling process has a negative nice value, the nice value is reset to " "zero in child processes." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:464 msgid "" "After the reset-on-fork flag has been enabled, it can be reset only if the " "thread has the B capability. This flag is disabled in child " "processes created by B(2)." msgstr "" #. type: SS #: man-pages/man7/sched.7:464 #, no-wrap msgid "Privileges and resource limits" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:476 msgid "" "In Linux kernels before 2.6.12, only privileged (B) threads " "can set a nonzero static priority (i.e., set a real-time scheduling policy). " " The only change that an unprivileged thread can make is to set the " "B policy, and this can be done only if the effective user ID of " "the caller matches the real or effective user ID of the target thread (i.e., " "the thread specified by I) whose policy is being changed." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:482 msgid "" "A thread must be privileged (B) in order to set or modify a " "B policy." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:492 msgid "" "Since Linux 2.6.12, the B resource limit defines a ceiling on " "an unprivileged thread's static priority for the B and " "B policies. The rules for changing scheduling policy and " "priority are as follows:" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:500 msgid "" "If an unprivileged thread has a nonzero B soft limit, then it " "can change its scheduling policy and priority, subject to the restriction " "that the priority cannot be set to a value higher than the maximum of its " "current priority and its B soft limit." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:505 msgid "" "If the B soft limit is 0, then the only permitted changes are " "to lower the priority, or to switch to a non-real-time policy." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:510 msgid "" "Subject to the same rules, another unprivileged thread can also make these " "changes, as long as the effective user ID of the thread making the change " "matches the real or effective user ID of the target thread." msgstr "" #. commit c02aa73b1d18e43cfd79c2f193b225e84ca497c8 #. type: Plain text #: man-pages/man7/sched.7:529 msgid "" "Special rules apply for the B policy. In Linux kernels before 2." "6.39, an unprivileged thread operating under this policy cannot change its " "policy, regardless of the value of its B resource limit. In " "Linux kernels since 2.6.39, an unprivileged thread can switch to either the " "B or the B policy so long as its nice value falls " "within the range permitted by its B resource limit (see " "B(2))." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:540 msgid "" "Privileged (B) threads ignore the B limit; as " "with older kernels, they can make arbitrary changes to scheduling policy and " "priority. See B(2) for further information on B." msgstr "" #. type: SS #: man-pages/man7/sched.7:540 #, no-wrap msgid "Limiting the CPU usage of real-time and deadline processes" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:553 msgid "" "A nonblocking infinite loop in a thread scheduled under the B, " "B, or B policy will block all threads with lower " "priority forever. Prior to Linux 2.6.25, the only way of preventing a " "runaway real-time process from freezing the system was to run (at the " "console) a shell scheduled under a higher static priority than the tested " "application. This allows an emergency kill of tested real-time applications " "that do not block or terminate as expected." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:563 msgid "" "Since Linux 2.6.25, there are other techniques for dealing with runaway real-" "time and deadline processes. One of these is to use the B " "resource limit to set a ceiling on the CPU time that a real-time process may " "consume. See B(2) for details." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:571 msgid "" "Since version 2.6.25, Linux also provides two I files that can be " "used to reserve a certain amount of CPU time to be used by non-real-time " "processes. Reserving some CPU time in this fashion allows some CPU time to " "be allocated to (say) a root shell that can be used to kill a runaway " "process. Both of these files specify time values in microseconds:" msgstr "" #. type: TP #: man-pages/man7/sched.7:571 #, no-wrap msgid "I" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:579 msgid "" "This file specifies a scheduling period that is equivalent to 100% CPU " "bandwidth. The value in this file can range from 1 to B, giving an " "operating range of 1 microsecond to around 35 minutes. The default value in " "this file is 1,000,000 (1 second)." msgstr "" #. type: TP #: man-pages/man7/sched.7:579 #, no-wrap msgid "I" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:592 msgid "" "The value in this file specifies how much of the \"period\" time can be used " "by all real-time and deadline scheduled processes on the system. The value " "in this file can range from -1 to B-1. Specifying -1 makes the " "runtime the same as the period; that is, no CPU time is set aside for non-" "real-time processes (which was the Linux behavior before kernel 2.6.25). " "The default value in this file is 950,000 (0.95 seconds), meaning that 5% of " "the CPU time is reserved for processes that don't run under a real-time or " "deadline scheduling policy." msgstr "" #. type: SS #: man-pages/man7/sched.7:593 #, no-wrap msgid "Response time" msgstr "" #. as described in #. .BR request_irq (9). #. type: Plain text #: man-pages/man7/sched.7:601 msgid "" "A blocked high priority thread waiting for I/O has a certain response time " "before it is scheduled again. The device driver writer can greatly reduce " "this response time by using a \"slow interrupt\" interrupt handler." msgstr "" #. type: SS #: man-pages/man7/sched.7:601 #, no-wrap msgid "Miscellaneous" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:606 msgid "" "Child processes inherit the scheduling policy and parameters across a " "B(2). The scheduling policy and parameters are preserved across " "B(2)." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:612 msgid "" "Memory locking is usually needed for real-time processes to avoid paging " "delays; this can be done with B(2) or B(2)." msgstr "" #. type: SH #: man-pages/man7/sched.7:612 #, no-wrap msgid "NOTES" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:623 msgid "" "Originally, Standard Linux was intended as a general-purpose operating " "system being able to handle background processes, interactive applications, " "and less demanding real-time applications (applications that need to usually " "meet timing deadlines). Although the Linux kernel 2.6 allowed for kernel " "preemption and the newly introduced O(1) scheduler ensures that the time " "needed to schedule is fixed and deterministic irrespective of the number of " "active tasks, true real-time computing was not possible up to kernel version " "2.6.17." msgstr "" #. type: SS #: man-pages/man7/sched.7:623 #, no-wrap msgid "Real-time features in the mainline Linux kernel" msgstr "" #. FIXME . Probably this text will need some minor tweaking #. by about the time of 2.6.30; ask Carsten Emde about this then. #. type: Plain text #: man-pages/man7/sched.7:637 msgid "" "From kernel version 2.6.18 onward, however, Linux is gradually becoming " "equipped with real-time capabilities, most of which are derived from the " "former I patches developed by Ingo Molnar, Thomas " "Gleixner, Steven Rostedt, and others. Until the patches have been " "completely merged into the mainline kernel (this is expected to be around " "kernel version 2.6.30), they must be installed to achieve the best real-time " "performance. These patches are named:" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:641 #, no-wrap msgid "patch-I-rtI\n" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:647 msgid "" "and can be downloaded from E<.UR http://www.kernel.org\\:/pub\\:/linux\\:/" "kernel\\:/projects\\:/rt/> E<.UE .>" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:656 msgid "" "Without the patches and prior to their full inclusion into the mainline " "kernel, the kernel configuration offers only the three preemption classes " "B, B, and " "B which respectively provide no, some, and " "considerable reduction of the worst-case scheduling latency." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:665 msgid "" "With the patches applied or after their full inclusion into the mainline " "kernel, the additional configuration item B becomes " "available. If this is selected, Linux is transformed into a regular real-" "time operating system. The FIFO and RR scheduling policies are then used to " "run a thread with true real-time priority and a minimum worst-case " "scheduling latency." msgstr "" #. type: SH #: man-pages/man7/sched.7:665 #, no-wrap msgid "SEE ALSO" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:691 msgid "" "B(1), B(2), B(2), B(2), B(2), " "B(2), B(2), B(2), " "B(2), B(2), " "B(2), B(2), B(2), " "B(2), B(2), B(2), " "B(2), B(2), B(3), " "B(3), B(3), B(7), " "B(7)" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:695 msgid "" "I by Bill O. Gallmeister, O'Reilly " "& Associates, Inc., ISBN 1-56592-074-0." msgstr "" #. type: Plain text #: man-pages/man7/sched.7:702 msgid "" "The Linux kernel source files I, " "I, I, and I" msgstr "" #. type: SH #: man-pages/man7/sched.7:702 #, no-wrap msgid "COLOPHON" msgstr "" #. type: Plain text #: man-pages/man7/sched.7:710 msgid "" "This page is part of release 3.70 of the Linux I project. A " "description of the project, information about reporting bugs, and the latest " "version of this page, can be found at \\%http://www.kernel.org/doc/man-pages/" "." msgstr ""