3 proc \- running processes
31 device serves a two-level directory structure.
32 The first level contains the
34 file (see below) and numbered directories
35 corresponding to pids of live processes;
36 each such directory contains a set of files
37 representing the corresponding process.
41 file contains the current memory image of the process.
42 A read or write at offset
44 which must be a valid virtual address,
45 accesses bytes from address
47 up to the end of the memory segment containing
49 Kernel virtual memory, including the kernel stack for the process and
50 saved user registers (whose addresses are machine-dependent),
51 can be accessed through
53 Writes are permitted only while the process is in the
55 state and only to user addresses or registers.
59 file contains the kernel per-process
61 Its main use is to recover the kernel stack and program counter
69 hold representations of the user-level registers, floating-point registers,
70 and kernel registers in machine-dependent form.
77 file lists the open file descriptors of the process.
78 The first line of the file is its current directory; subsequent lines list, one per line,
79 the open files, giving the decimal file descriptor number; whether the file is open for read
85 the type, device number, and qid of the file; its I/O unit (the amount of data
86 that may be transferred on the file as a contiguous piece; see
88 its I/O offset; and its name at the time it was opened.
92 file contains a textual representation of the process's file name space, in the format of
98 The last line of the file identifies the current working directory of the process, in the form of a
103 The information in this file is based on the names files had when the name space was assembled,
104 so the names it contains may be inaccessible if the files have been subsequently renamed or rearranged.
108 file contains a textual display of the memory segments
109 attached to the process. Each line has multiple fields:
110 the type of segment (\c
115 etc.); one-letter flags such as
117 for read-only, if any;
118 starting virtual address, in hexadecimal;
119 ending virtual address, and reference count.
123 file contains a string with twelve fields, each followed by a space.
126 the process name and user name, each 27 characters left justified
128 the process state, 11 characters left justified (see
131 the six 11-character numbers also held in the process's
135 the amount of memory used by the process, except its stack,
136 in units of 1024 bytes
138 the base and current scheduling priority, each 11 character numbers
142 file contains the arguments of the program when it was created by
144 If the program was not created by
151 The format of the file is a list of quoted strings suitable for
158 file is a pseudonym for the file
159 from which the process was executed;
160 its main use is to recover the symbol table of the process.
164 file may be read to recover
165 records from the exiting children of the process in the format of
169 If the process has no extant children, living or exited,
173 It is an error for a process to attempt to read its own
175 file when it has no children.
179 the process will draw an error
182 system call; similarly, if a process is in an
186 file cannot be read by any process.
190 file contains the instruction frequency count information used for multiprocess profiling; see
194 The information is gleaned by sampling the program's user-level program counter
197 Strings written to the
199 file will be posted as a note to the process
202 The note should be less than
205 the last character is reserved for a terminating NUL character.
208 characters will retrieve the oldest note posted to the
209 process and prevent its delivery to the process.
212 file is similar, but the note will be delivered to all the
213 processes in the target process's
217 However, if the process doing the write is in the group,
218 it will not receive the note.
225 file may be read to recover an integer identifying the note group of the process
230 The file may be written to cause the process to change to another note group,
231 provided the group exists and is owned by the same user.
235 can be opened once and read to see trace events from processes that have
241 Each event produces, in native machine format, the
248 .B /sys/include/trace.h
250 .BR /sys/src/cmd/trace.c ).
253 Textual messages written to the
255 file control the execution of the process.
256 Some require that the process is in a particular state
257 and return an error if it is not.
260 Suspend execution of the process, putting it in the
265 Resume execution of a
270 Do not affect the process directly but, like all other messages ending with
272 block the process writing the
274 file until the target process is in the
280 if the target process would receive a note while the message is pending,
281 it is instead stopped and the debugging process is resumed.
286 process to resume, and then do a
291 Set a bit in the process so that,
294 system call, it will enter the
296 state before returning to user mode.
297 This bit is inherited across
303 Close file descriptor
308 Close all open file descriptors in the process.
314 Don't allow this process to be swapped out. This should
315 be used carefully and sparingly or the system could run
316 out of memory. It is meant for processes that can't be
317 swapped, like the ones implementing the swap device and for
318 processes containing sensitive data.
321 Kill the process the next time it crosses the user/kernel boundary.
324 Make it impossible to read the process's user memory.
325 This property is inherited on fork, cleared on
327 and is not otherwise resettable.
330 Set the base priority for the process to the integer
334 Wire the process to processor
338 Without an argument, toggle trace event generation for this process into
341 With a zero argument, tracing for the proc is turned off, with a non-zero numeric
342 argument, it is turned on.
345 Set the real-time scheduling period of the process to
349 is an optionally signed number containing an optional decimal point and
358 empty. The time is interpreted, respectively, as
364 or, in the case of an absent units specifier, as
366 If the time specifier is signed, it is interpreted as an increment or decrement
367 from a previously set value. See also the
372 Set the real-time deadline interval of the process to
378 are interpreted as for
383 Set the real-time cost (maximum CPU time per period) of the process to
389 are interpreted as for
394 Use sporadic scheduling for the real-time process. The description of the
396 command below contains further details.
399 Make the real-time process yield on blocking I/O.
400 The description of the
402 command below contains further details.
416 perform a schedulability test and start scheduling the process as a real-time
417 process if the test succeeds. If the test fails, the
419 will fail with error set to the reason for failure.
422 Add a user event to the
427 .SS Real-time scheduling
429 processes are periodically
431 giving them a higher priority than non-real-time processes until they either
432 give up the processor voluntarily, they exhaust their CPU allocation, or they reach their
434 The moment of release is dictated by the
436 and whether the process is
439 Non-sporadic processes are called
441 and they are released precisely at intervals of their period (but periods can be skipped
442 if the process blocks on I/O).
443 Sporadic processes are released whenever they become
444 runnable (after being blocked by
446 or I/O), but always at least an interval of
448 after the previous release.
452 of a real-time process specifies that the process must complete within the first
456 The dealine must be less than or equal to the period.
457 If it is not specified, it is set to the period.
461 of a real-time process describes the maximum CPU time the process may use per period.
463 A real-time process can give up the CPU before its deadline is reached
464 or its allocation is exhausted.
465 It does this by calling
469 is specified, it also does it by executing any blocking system call.
475 Of the released processes,
476 the one with the earliest deadline has the highest priority.
477 Care should be taken using spin locks (see
479 because a real-time process spinning on a lock will not give up the processor until
480 its CPU allocation is exhausted; this is unlikely to be the desired behavior.
482 When a real-time process reaches its deadline or exhausts its CPU allocation, it remains
483 schedulable, but at a very low priority.
485 The priority is interpreted by Plan 9's multilevel process scheduler.
486 Priorities run from 0 to 19, with higher
487 numbers representing higher priorities.
488 A process has a base priority and
489 a running priority which is less than or equal to the base priority.
490 As a process uses up more of its allocated time, its priority is lowered.
492 explicitly set, user processes have base priority 10, kernel processes
494 Children inherit the parent's base priority.
497 .B /sys/src/9/*/mem.h
498 .B /sys/src/9/*/dat.h
499 .B /sys/include/trace.h
507 .B /sys/src/9/port/devproc.c
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