projects/linux·blob master · refs

623 lines · 33.8 KiB

1.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0)
2
3======================================================
4Discovering Linux kernel subsystems used by a workload
5======================================================
6
7:Authors: - Shuah Khan <[email protected]>
8 - Shefali Sharma <[email protected]>
9:maintained-by: Shuah Khan <[email protected]>
10
11Key Points
12==========
13
14 * Understanding system resources necessary to build and run a workload
15 is important.
16 * Linux tracing and strace can be used to discover the system resources
17 in use by a workload. The completeness of the system usage information
18 depends on the completeness of coverage of a workload.
19 * Performance and security of the operating system can be analyzed with
20 the help of tools such as:
21 `perf <https://man7.org/linux/man-pages/man1/perf.1.html>`_,
22 `stress-ng <https://www.mankier.com/1/stress-ng>`_,
23 `paxtest <https://github.com/opntr/paxtest-freebsd>`_.
24 * Once we discover and understand the workload needs, we can focus on them
25 to avoid regressions and use it to evaluate safety considerations.
26
27Methodology
28===========
29
30`strace <https://man7.org/linux/man-pages/man1/strace.1.html>`_ is a
31diagnostic, instructional, and debugging tool and can be used to discover
32the system resources in use by a workload. Once we discover and understand
33the workload needs, we can focus on them to avoid regressions and use it
34to evaluate safety considerations. We use strace tool to trace workloads.
35
36This method of tracing using strace tells us the system calls invoked by
37the workload and doesn't include all the system calls that can be invoked
38by it. In addition, this tracing method tells us just the code paths within
39these system calls that are invoked. As an example, if a workload opens a
40file and reads from it successfully, then the success path is the one that
41is traced. Any error paths in that system call will not be traced. If there
42is a workload that provides full coverage of a workload then the method
43outlined here will trace and find all possible code paths. The completeness
44of the system usage information depends on the completeness of coverage of a
45workload.
46
47The goal is tracing a workload on a system running a default kernel without
48requiring custom kernel installs.
49
50How do we gather fine-grained system information?
51=================================================
52
53strace tool can be used to trace system calls made by a process and signals
54it receives. System calls are the fundamental interface between an
55application and the operating system kernel. They enable a program to
56request services from the kernel. For instance, the open() system call in
57Linux is used to provide access to a file in the file system. strace enables
58us to track all the system calls made by an application. It lists all the
59system calls made by a process and their resulting output.
60
61You can generate profiling data combining strace and perf record tools to
62record the events and information associated with a process. This provides
63insight into the process. "perf annotate" tool generates the statistics of
64each instruction of the program. This document goes over the details of how
65to gather fine-grained information on a workload's usage of system resources.
66
67We used strace to trace the perf, stress-ng, paxtest workloads to illustrate
68our methodology to discover resources used by a workload. This process can
69be applied to trace other workloads.
70
71Getting the system ready for tracing
72====================================
73
74Before we can get started we will show you how to get your system ready.
75We assume that you have a Linux distribution running on a physical system
76or a virtual machine. Most distributions will include strace command. Let’s
77install other tools that aren’t usually included to build Linux kernel.
78Please note that the following works on Debian based distributions. You
79might have to find equivalent packages on other Linux distributions.
80
81Install tools to build Linux kernel and tools in kernel repository.
82scripts/ver_linux is a good way to check if your system already has
83the necessary tools::
84
85 sudo apt-get install build-essential flex bison yacc
86 sudo apt install libelf-dev systemtap-sdt-dev libslang2-dev libperl-dev libdw-dev
87
88cscope is a good tool to browse kernel sources. Let's install it now::
89
90 sudo apt-get install cscope
91
92Install stress-ng and paxtest::
93
94 apt-get install stress-ng
95 apt-get install paxtest
96
97Workload overview
98=================
99
100As mentioned earlier, we used strace to trace perf bench, stress-ng and
101paxtest workloads to show how to analyze a workload and identify Linux
102subsystems used by these workloads. Let's start with an overview of these
103three workloads to get a better understanding of what they do and how to
104use them.
105
106perf bench (all) workload
107-------------------------
108
109The perf bench command contains multiple multi-threaded microkernel
110benchmarks for executing different subsystems in the Linux kernel and
111system calls. This allows us to easily measure the impact of changes,
112which can help mitigate performance regressions. It also acts as a common
113benchmarking framework, enabling developers to easily create test cases,
114integrate transparently, and use performance-rich tooling subsystems.
115
116Stress-ng netdev stressor workload
117----------------------------------
118
119stress-ng is used for performing stress testing on the kernel. It allows
120you to exercise various physical subsystems of the computer, as well as
121interfaces of the OS kernel, using "stressor-s". They are available for
122CPU, CPU cache, devices, I/O, interrupts, file system, memory, network,
123operating system, pipelines, schedulers, and virtual machines. Please refer
124to the `stress-ng man-page <https://www.mankier.com/1/stress-ng>`_ to
125find the description of all the available stressor-s. The netdev stressor
126starts specified number (N) of workers that exercise various netdevice
127ioctl commands across all the available network devices.
128
129paxtest kiddie workload
130-----------------------
131
132paxtest is a program that tests buffer overflows in the kernel. It tests
133kernel enforcements over memory usage. Generally, execution in some memory
134segments makes buffer overflows possible. It runs a set of programs that
135attempt to subvert memory usage. It is used as a regression test suite for
136PaX, but might be useful to test other memory protection patches for the
137kernel. We used paxtest kiddie mode which looks for simple vulnerabilities.
138
139What is strace and how do we use it?
140====================================
141
142As mentioned earlier, strace which is a useful diagnostic, instructional,
143and debugging tool and can be used to discover the system resources in use
144by a workload. It can be used:
145
146 * To see how a process interacts with the kernel.
147 * To see why a process is failing or hanging.
148 * For reverse engineering a process.
149 * To find the files on which a program depends.
150 * For analyzing the performance of an application.
151 * For troubleshooting various problems related to the operating system.
152
153In addition, strace can generate run-time statistics on times, calls, and
154errors for each system call and report a summary when program exits,
155suppressing the regular output. This attempts to show system time (CPU time
156spent running in the kernel) independent of wall clock time. We plan to use
157these features to get information on workload system usage.
158
159strace command supports basic, verbose, and stats modes. strace command when
160run in verbose mode gives more detailed information about the system calls
161invoked by a process.
162
163Running strace -c generates a report of the percentage of time spent in each
164system call, the total time in seconds, the microseconds per call, the total
165number of calls, the count of each system call that has failed with an error
166and the type of system call made.
167
168 * Usage: strace <command we want to trace>
169 * Verbose mode usage: strace -v <command>
170 * Gather statistics: strace -c <command>
171
172We used the “-c” option to gather fine-grained run-time statistics in use
173by three workloads we have chose for this analysis.
174
175 * perf
176 * stress-ng
177 * paxtest
178
179What is cscope and how do we use it?
180====================================
181
182Now let’s look at `cscope <https://cscope.sourceforge.net/>`_, a command
183line tool for browsing C, C++ or Java code-bases. We can use it to find
184all the references to a symbol, global definitions, functions called by a
185function, functions calling a function, text strings, regular expression
186patterns, files including a file.
187
188We can use cscope to find which system call belongs to which subsystem.
189This way we can find the kernel subsystems used by a process when it is
190executed.
191
192Let’s checkout the latest Linux repository and build cscope database::
193
194 git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux
195 cd linux
196 cscope -R -p10 # builds cscope.out database before starting browse session
197 cscope -d -p10 # starts browse session on cscope.out database
198
199Note: Run "cscope -R -p10" to build the database and "cscope -d -p10" to
200enter into the browsing session. cscope by default uses the cscope.out
201database. To get out of this mode press ctrl+d. -p option is used to
202specify the number of file path components to display. -p10 is optimal
203for browsing kernel sources.
204
205Alternatively, the kernel build system can generate the cscope database::
206
207 make cscope
208
209To exclude directories from the generated database, pass IGNORE_DIRS to
210the cscope target. For example, to exclude Documentation/, run::
211
212 make IGNORE_DIRS="Documentation" cscope
213
214What is perf and how do we use it?
215==================================
216
217Perf is an analysis tool based on Linux 2.6+ systems, which abstracts the
218CPU hardware difference in performance measurement in Linux, and provides
219a simple command line interface. Perf is based on the perf_events interface
220exported by the kernel. It is very useful for profiling the system and
221finding performance bottlenecks in an application.
222
223If you haven't already checked out the Linux mainline repository, you can do
224so and then build kernel and perf tool::
225
226 git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux
227 cd linux
228 make -j3 all
229 cd tools/perf
230 make
231
232Note: The perf command can be built without building the kernel in the
233repository and can be run on older kernels. However matching the kernel
234and perf revisions gives more accurate information on the subsystem usage.
235
236We used "perf stat" and "perf bench" options. For a detailed information on
237the perf tool, run "perf -h".
238
239perf stat
240---------
241The perf stat command generates a report of various hardware and software
242events. It does so with the help of hardware counter registers found in
243modern CPUs that keep the count of these activities. "perf stat cal" shows
244stats for cal command.
245
246Perf bench
247----------
248The perf bench command contains multiple multi-threaded microkernel
249benchmarks for executing different subsystems in the Linux kernel and
250system calls. This allows us to easily measure the impact of changes,
251which can help mitigate performance regressions. It also acts as a common
252benchmarking framework, enabling developers to easily create test cases,
253integrate transparently, and use performance-rich tooling.
254
255"perf bench all" runs all available benchmarks in the perf bench
256framework. The exact set of benchmarks depends on the perf version and on
257the features enabled when perf was built.
258
259To list the benchmark collections available on the current system, run::
260
261 perf bench
262
263To list benchmarks in a collection, run::
264
265 perf bench <collection>
266
267For example, to list the benchmarks in the mem collection, run::
268
269 perf bench mem
270
271What is stress-ng and how do we use it?
272=======================================
273
274As mentioned earlier, stress-ng is used for performing stress testing on
275the kernel. It allows you to exercise various physical subsystems of the
276computer, as well as interfaces of the OS kernel, using stressor-s. They
277are available for CPU, CPU cache, devices, I/O, interrupts, file system,
278memory, network, operating system, pipelines, schedulers, and virtual
279machines.
280
281The netdev stressor starts N workers that exercise various netdevice ioctl
282commands across all the available network devices. The following ioctls are
283exercised:
284
285 * SIOCGIFCONF, SIOCGIFINDEX, SIOCGIFNAME, SIOCGIFFLAGS
286 * SIOCGIFADDR, SIOCGIFNETMASK, SIOCGIFMETRIC, SIOCGIFMTU
287 * SIOCGIFHWADDR, SIOCGIFMAP, SIOCGIFTXQLEN
288
289The following command runs the stressor::
290
291 stress-ng --netdev 1 -t 60 --metrics
292
293We can use the perf record command to record the events and information
294associated with a process. This command records the profiling data in the
295perf.data file in the same directory.
296
297Using the following commands you can record the events associated with the
298netdev stressor, view the generated report perf.data and annotate the output
299to view the statistics of each instruction of the program::
300
301 perf record -- stress-ng --netdev 1 -t 60 --metrics
302 perf report
303 perf annotate
304
305What is paxtest and how do we use it?
306=====================================
307
308paxtest is a program that tests buffer overflows in the kernel. It tests
309kernel enforcements over memory usage. Generally, execution in some memory
310segments makes buffer overflows possible. It runs a set of programs that
311attempt to subvert memory usage. It is used as a regression test suite for
312PaX, and will be useful to test other memory protection patches for the
313kernel.
314
315paxtest provides kiddie and blackhat modes. The paxtest kiddie mode runs
316in normal mode, whereas the blackhat mode tries to get around the protection
317of the kernel testing for vulnerabilities. We focus on the kiddie mode here
318and combine "paxtest kiddie" run with "perf record" to collect CPU stack
319traces for the paxtest kiddie run to see which function is calling other
320functions in the performance profile. Then the "dwarf" (DWARF's Call Frame
321Information) mode can be used to unwind the stack.
322
323The following command can be used to view resulting report in call-graph
324format::
325
326 perf record --call-graph dwarf paxtest kiddie
327 perf report --stdio
328
329Tracing workloads
330=================
331
332Now that we understand the workloads, let's start tracing them.
333
334Tracing perf bench all workload
335-------------------------------
336
337Run the following command to trace perf bench all workload::
338
339 strace -c perf bench all
340
341**System Calls made by the workload**
342
343The below table shows the system calls invoked by the workload, number of
344times each system call is invoked, and the corresponding Linux subsystem.
345
346+-------------------+-----------+-----------------+-------------------------+
347| System Call | # calls | Linux Subsystem | System Call (API) |
348+===================+===========+=================+=========================+
349| getppid | 10000001 | Process Mgmt | sys_getpid() |
350+-------------------+-----------+-----------------+-------------------------+
351| clone | 1077 | Process Mgmt. | sys_clone() |
352+-------------------+-----------+-----------------+-------------------------+
353| prctl | 23 | Process Mgmt. | sys_prctl() |
354+-------------------+-----------+-----------------+-------------------------+
355| prlimit64 | 7 | Process Mgmt. | sys_prlimit64() |
356+-------------------+-----------+-----------------+-------------------------+
357| getpid | 10 | Process Mgmt. | sys_getpid() |
358+-------------------+-----------+-----------------+-------------------------+
359| uname | 3 | Process Mgmt. | sys_uname() |
360+-------------------+-----------+-----------------+-------------------------+
361| sysinfo | 1 | Process Mgmt. | sys_sysinfo() |
362+-------------------+-----------+-----------------+-------------------------+
363| getuid | 1 | Process Mgmt. | sys_getuid() |
364+-------------------+-----------+-----------------+-------------------------+
365| getgid | 1 | Process Mgmt. | sys_getgid() |
366+-------------------+-----------+-----------------+-------------------------+
367| geteuid | 1 | Process Mgmt. | sys_geteuid() |
368+-------------------+-----------+-----------------+-------------------------+
369| getegid | 1 | Process Mgmt. | sys_getegid() |
370+-------------------+-----------+-----------------+-------------------------+
371| close | 49951 | Filesystem | sys_close() |
372+-------------------+-----------+-----------------+-------------------------+
373| pipe | 604 | Filesystem | sys_pipe() |
374+-------------------+-----------+-----------------+-------------------------+
375| openat | 48560 | Filesystem | sys_openat() |
376+-------------------+-----------+-----------------+-------------------------+
377| fstat | 8338 | Filesystem | sys_fstat() |
378+-------------------+-----------+-----------------+-------------------------+
379| stat | 1573 | Filesystem | sys_stat() |
380+-------------------+-----------+-----------------+-------------------------+
381| pread64 | 9646 | Filesystem | sys_pread64() |
382+-------------------+-----------+-----------------+-------------------------+
383| getdents64 | 1873 | Filesystem | sys_getdents64() |
384+-------------------+-----------+-----------------+-------------------------+
385| access | 3 | Filesystem | sys_access() |
386+-------------------+-----------+-----------------+-------------------------+
387| lstat | 1880 | Filesystem | sys_lstat() |
388+-------------------+-----------+-----------------+-------------------------+
389| lseek | 6 | Filesystem | sys_lseek() |
390+-------------------+-----------+-----------------+-------------------------+
391| ioctl | 3 | Filesystem | sys_ioctl() |
392+-------------------+-----------+-----------------+-------------------------+
393| dup2 | 1 | Filesystem | sys_dup2() |
394+-------------------+-----------+-----------------+-------------------------+
395| execve | 2 | Filesystem | sys_execve() |
396+-------------------+-----------+-----------------+-------------------------+
397| fcntl | 8779 | Filesystem | sys_fcntl() |
398+-------------------+-----------+-----------------+-------------------------+
399| statfs | 1 | Filesystem | sys_statfs() |
400+-------------------+-----------+-----------------+-------------------------+
401| epoll_create | 2 | Filesystem | sys_epoll_create() |
402+-------------------+-----------+-----------------+-------------------------+
403| epoll_ctl | 64 | Filesystem | sys_epoll_ctl() |
404+-------------------+-----------+-----------------+-------------------------+
405| newfstatat | 8318 | Filesystem | sys_newfstatat() |
406+-------------------+-----------+-----------------+-------------------------+
407| eventfd2 | 192 | Filesystem | sys_eventfd2() |
408+-------------------+-----------+-----------------+-------------------------+
409| mmap | 243 | Memory Mgmt. | sys_mmap() |
410+-------------------+-----------+-----------------+-------------------------+
411| mprotect | 32 | Memory Mgmt. | sys_mprotect() |
412+-------------------+-----------+-----------------+-------------------------+
413| brk | 21 | Memory Mgmt. | sys_brk() |
414+-------------------+-----------+-----------------+-------------------------+
415| munmap | 128 | Memory Mgmt. | sys_munmap() |
416+-------------------+-----------+-----------------+-------------------------+
417| set_mempolicy | 156 | Memory Mgmt. | sys_set_mempolicy() |
418+-------------------+-----------+-----------------+-------------------------+
419| set_tid_address | 1 | Process Mgmt. | sys_set_tid_address() |
420+-------------------+-----------+-----------------+-------------------------+
421| set_robust_list | 1 | Futex | sys_set_robust_list() |
422+-------------------+-----------+-----------------+-------------------------+
423| futex | 341 | Futex | sys_futex() |
424+-------------------+-----------+-----------------+-------------------------+
425| sched_getaffinity | 79 | Scheduler | sys_sched_getaffinity() |
426+-------------------+-----------+-----------------+-------------------------+
427| sched_setaffinity | 223 | Scheduler | sys_sched_setaffinity() |
428+-------------------+-----------+-----------------+-------------------------+
429| socketpair | 202 | Network | sys_socketpair() |
430+-------------------+-----------+-----------------+-------------------------+
431| rt_sigprocmask | 21 | Signal | sys_rt_sigprocmask() |
432+-------------------+-----------+-----------------+-------------------------+
433| rt_sigaction | 36 | Signal | sys_rt_sigaction() |
434+-------------------+-----------+-----------------+-------------------------+
435| rt_sigreturn | 2 | Signal | sys_rt_sigreturn() |
436+-------------------+-----------+-----------------+-------------------------+
437| wait4 | 889 | Time | sys_wait4() |
438+-------------------+-----------+-----------------+-------------------------+
439| clock_nanosleep | 37 | Time | sys_clock_nanosleep() |
440+-------------------+-----------+-----------------+-------------------------+
441| capget | 4 | Capability | sys_capget() |
442+-------------------+-----------+-----------------+-------------------------+
443
444Tracing stress-ng netdev stressor workload
445------------------------------------------
446
447Run the following command to trace stress-ng netdev stressor workload::
448
449 strace -c stress-ng --netdev 1 -t 60 --metrics
450
451**System Calls made by the workload**
452
453The below table shows the system calls invoked by the workload, number of
454times each system call is invoked, and the corresponding Linux subsystem.
455
456+-------------------+-----------+-----------------+-------------------------+
457| System Call | # calls | Linux Subsystem | System Call (API) |
458+===================+===========+=================+=========================+
459| openat | 74 | Filesystem | sys_openat() |
460+-------------------+-----------+-----------------+-------------------------+
461| close | 75 | Filesystem | sys_close() |
462+-------------------+-----------+-----------------+-------------------------+
463| read | 58 | Filesystem | sys_read() |
464+-------------------+-----------+-----------------+-------------------------+
465| fstat | 20 | Filesystem | sys_fstat() |
466+-------------------+-----------+-----------------+-------------------------+
467| flock | 10 | Filesystem | sys_flock() |
468+-------------------+-----------+-----------------+-------------------------+
469| write | 7 | Filesystem | sys_write() |
470+-------------------+-----------+-----------------+-------------------------+
471| getdents64 | 8 | Filesystem | sys_getdents64() |
472+-------------------+-----------+-----------------+-------------------------+
473| pread64 | 8 | Filesystem | sys_pread64() |
474+-------------------+-----------+-----------------+-------------------------+
475| lseek | 1 | Filesystem | sys_lseek() |
476+-------------------+-----------+-----------------+-------------------------+
477| access | 2 | Filesystem | sys_access() |
478+-------------------+-----------+-----------------+-------------------------+
479| getcwd | 1 | Filesystem | sys_getcwd() |
480+-------------------+-----------+-----------------+-------------------------+
481| execve | 1 | Filesystem | sys_execve() |
482+-------------------+-----------+-----------------+-------------------------+
483| mmap | 61 | Memory Mgmt. | sys_mmap() |
484+-------------------+-----------+-----------------+-------------------------+
485| munmap | 3 | Memory Mgmt. | sys_munmap() |
486+-------------------+-----------+-----------------+-------------------------+
487| mprotect | 20 | Memory Mgmt. | sys_mprotect() |
488+-------------------+-----------+-----------------+-------------------------+
489| mlock | 2 | Memory Mgmt. | sys_mlock() |
490+-------------------+-----------+-----------------+-------------------------+
491| brk | 3 | Memory Mgmt. | sys_brk() |
492+-------------------+-----------+-----------------+-------------------------+
493| rt_sigaction | 21 | Signal | sys_rt_sigaction() |
494+-------------------+-----------+-----------------+-------------------------+
495| rt_sigprocmask | 1 | Signal | sys_rt_sigprocmask() |
496+-------------------+-----------+-----------------+-------------------------+
497| sigaltstack | 1 | Signal | sys_sigaltstack() |
498+-------------------+-----------+-----------------+-------------------------+
499| rt_sigreturn | 1 | Signal | sys_rt_sigreturn() |
500+-------------------+-----------+-----------------+-------------------------+
501| getpid | 8 | Process Mgmt. | sys_getpid() |
502+-------------------+-----------+-----------------+-------------------------+
503| prlimit64 | 5 | Process Mgmt. | sys_prlimit64() |
504+-------------------+-----------+-----------------+-------------------------+
505| arch_prctl | 2 | Process Mgmt. | sys_arch_prctl() |
506+-------------------+-----------+-----------------+-------------------------+
507| sysinfo | 2 | Process Mgmt. | sys_sysinfo() |
508+-------------------+-----------+-----------------+-------------------------+
509| getuid | 2 | Process Mgmt. | sys_getuid() |
510+-------------------+-----------+-----------------+-------------------------+
511| uname | 1 | Process Mgmt. | sys_uname() |
512+-------------------+-----------+-----------------+-------------------------+
513| setpgid | 1 | Process Mgmt. | sys_setpgid() |
514+-------------------+-----------+-----------------+-------------------------+
515| getrusage | 1 | Process Mgmt. | sys_getrusage() |
516+-------------------+-----------+-----------------+-------------------------+
517| geteuid | 1 | Process Mgmt. | sys_geteuid() |
518+-------------------+-----------+-----------------+-------------------------+
519| getppid | 1 | Process Mgmt. | sys_getppid() |
520+-------------------+-----------+-----------------+-------------------------+
521| sendto | 3 | Network | sys_sendto() |
522+-------------------+-----------+-----------------+-------------------------+
523| connect | 1 | Network | sys_connect() |
524+-------------------+-----------+-----------------+-------------------------+
525| socket | 1 | Network | sys_socket() |
526+-------------------+-----------+-----------------+-------------------------+
527| clone | 1 | Process Mgmt. | sys_clone() |
528+-------------------+-----------+-----------------+-------------------------+
529| set_tid_address | 1 | Process Mgmt. | sys_set_tid_address() |
530+-------------------+-----------+-----------------+-------------------------+
531| wait4 | 2 | Time | sys_wait4() |
532+-------------------+-----------+-----------------+-------------------------+
533| alarm | 1 | Time | sys_alarm() |
534+-------------------+-----------+-----------------+-------------------------+
535| set_robust_list | 1 | Futex | sys_set_robust_list() |
536+-------------------+-----------+-----------------+-------------------------+
537
538Tracing paxtest kiddie workload
539-------------------------------
540
541Run the following command to trace paxtest kiddie workload::
542
543 strace -c paxtest kiddie
544
545**System Calls made by the workload**
546
547The below table shows the system calls invoked by the workload, number of
548times each system call is invoked, and the corresponding Linux subsystem.
549
550+-------------------+-----------+-----------------+----------------------+
551| System Call | # calls | Linux Subsystem | System Call (API) |
552+===================+===========+=================+======================+
553| read | 3 | Filesystem | sys_read() |
554+-------------------+-----------+-----------------+----------------------+
555| write | 11 | Filesystem | sys_write() |
556+-------------------+-----------+-----------------+----------------------+
557| close | 41 | Filesystem | sys_close() |
558+-------------------+-----------+-----------------+----------------------+
559| stat | 24 | Filesystem | sys_stat() |
560+-------------------+-----------+-----------------+----------------------+
561| fstat | 2 | Filesystem | sys_fstat() |
562+-------------------+-----------+-----------------+----------------------+
563| pread64 | 6 | Filesystem | sys_pread64() |
564+-------------------+-----------+-----------------+----------------------+
565| access | 1 | Filesystem | sys_access() |
566+-------------------+-----------+-----------------+----------------------+
567| pipe | 1 | Filesystem | sys_pipe() |
568+-------------------+-----------+-----------------+----------------------+
569| dup2 | 24 | Filesystem | sys_dup2() |
570+-------------------+-----------+-----------------+----------------------+
571| execve | 1 | Filesystem | sys_execve() |
572+-------------------+-----------+-----------------+----------------------+
573| fcntl | 26 | Filesystem | sys_fcntl() |
574+-------------------+-----------+-----------------+----------------------+
575| openat | 14 | Filesystem | sys_openat() |
576+-------------------+-----------+-----------------+----------------------+
577| rt_sigaction | 7 | Signal | sys_rt_sigaction() |
578+-------------------+-----------+-----------------+----------------------+
579| rt_sigreturn | 38 | Signal | sys_rt_sigreturn() |
580+-------------------+-----------+-----------------+----------------------+
581| clone | 38 | Process Mgmt. | sys_clone() |
582+-------------------+-----------+-----------------+----------------------+
583| wait4 | 44 | Time | sys_wait4() |
584+-------------------+-----------+-----------------+----------------------+
585| mmap | 7 | Memory Mgmt. | sys_mmap() |
586+-------------------+-----------+-----------------+----------------------+
587| mprotect | 3 | Memory Mgmt. | sys_mprotect() |
588+-------------------+-----------+-----------------+----------------------+
589| munmap | 1 | Memory Mgmt. | sys_munmap() |
590+-------------------+-----------+-----------------+----------------------+
591| brk | 3 | Memory Mgmt. | sys_brk() |
592+-------------------+-----------+-----------------+----------------------+
593| getpid | 1 | Process Mgmt. | sys_getpid() |
594+-------------------+-----------+-----------------+----------------------+
595| getuid | 1 | Process Mgmt. | sys_getuid() |
596+-------------------+-----------+-----------------+----------------------+
597| getgid | 1 | Process Mgmt. | sys_getgid() |
598+-------------------+-----------+-----------------+----------------------+
599| geteuid | 2 | Process Mgmt. | sys_geteuid() |
600+-------------------+-----------+-----------------+----------------------+
601| getegid | 1 | Process Mgmt. | sys_getegid() |
602+-------------------+-----------+-----------------+----------------------+
603| getppid | 1 | Process Mgmt. | sys_getppid() |
604+-------------------+-----------+-----------------+----------------------+
605| arch_prctl | 2 | Process Mgmt. | sys_arch_prctl() |
606+-------------------+-----------+-----------------+----------------------+
607
608Conclusion
609==========
610
611This document is intended to be used as a guide on how to gather fine-grained
612information on the resources in use by workloads using strace.
613
614References
615==========
616
617 * `Discovery Linux Kernel Subsystems used by OpenAPS <https://elisa.tech/blog/2022/02/02/discovery-linux-kernel-subsystems-used-by-openaps>`_
618 * `ELISA-White-Papers-Discovering Linux kernel subsystems used by a workload <https://github.com/elisa-tech/ELISA-White-Papers/blob/master/Processes/Discovering_Linux_kernel_subsystems_used_by_a_workload.md>`_
619 * `strace <https://man7.org/linux/man-pages/man1/strace.1.html>`_
620 * `perf <https://man7.org/linux/man-pages/man1/perf.1.html>`_
621 * `paxtest README <https://github.com/opntr/paxtest-freebsd/blob/hardenedbsd/0.9.14-hbsd/README>`_
622 * `stress-ng <https://www.mankier.com/1/stress-ng>`_
623 * `Monitoring and managing system status and performance <https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/monitoring_and_managing_system_status_and_performance/index>`_