From eca7de7cdc382eb6e0d344c07b1449ed75f5b435 Mon Sep 17 00:00:00 2001 From: Wang Yong Date: Mon, 13 Feb 2023 14:08:08 +0800 Subject: delayacct: improve the average delay precision of getdelay tool to microsecond Improve the average delay precision of getdelay tool to microsecond. When using the getdelay tool, it is sometimes found that the average delay except CPU is not 0, but display is 0, because the precison is too low. For example, see delay average of SWAP below when using ZRAM. print delayacct stats ON PID 32915 CPU count real total virtual total delay total delay average 339202 2793871936 9233585504 7951112 0.000ms IO count delay total delay average 41 419296904 10ms SWAP count delay total delay average 242589 1045792384 0ms This wrong display is misleading, so improve the millisecond precision of the average delay to microsecond just like CPU. Then user would get more accurate information of delay time. Link: https://lkml.kernel.org/r/202302131408087983857@zte.com.cn Signed-off-by: Wang Yong Reviewed-by: Yang Yang Cc: David Hildenbrand Signed-off-by: Andrew Morton --- Documentation/accounting/delay-accounting.rst | 14 +++++++------- .../translations/zh_CN/accounting/delay-accounting.rst | 10 +++++----- 2 files changed, 12 insertions(+), 12 deletions(-) (limited to 'Documentation') diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst index 7103b62ba6d7..79f537c9f160 100644 --- a/Documentation/accounting/delay-accounting.rst +++ b/Documentation/accounting/delay-accounting.rst @@ -109,17 +109,17 @@ Get sum of delays, since system boot, for all pids with tgid 5:: CPU count real total virtual total delay total delay average 8 7000000 6872122 3382277 0.423ms IO count delay total delay average - 0 0 0ms + 0 0 0.000ms SWAP count delay total delay average - 0 0 0ms + 0 0 0.000ms RECLAIM count delay total delay average - 0 0 0ms + 0 0 0.000ms THRASHING count delay total delay average - 0 0 0ms + 0 0 0.000ms COMPACT count delay total delay average - 0 0 0ms - WPCOPY count delay total delay average - 0 0 0ms + 0 0 0.000ms + WPCOPY count delay total delay average + 0 0 0.000ms Get IO accounting for pid 1, it works only with -p:: diff --git a/Documentation/translations/zh_CN/accounting/delay-accounting.rst b/Documentation/translations/zh_CN/accounting/delay-accounting.rst index a01dc3d5b0db..7b8693ccf80a 100644 --- a/Documentation/translations/zh_CN/accounting/delay-accounting.rst +++ b/Documentation/translations/zh_CN/accounting/delay-accounting.rst @@ -92,15 +92,15 @@ getdelays命令的一般格式:: CPU count real total virtual total delay total delay average 8 7000000 6872122 3382277 0.423ms IO count delay total delay average - 0 0 0ms + 0 0 0.000ms SWAP count delay total delay average - 0 0 0ms + 0 0 0.000ms RECLAIM count delay total delay average - 0 0 0ms + 0 0 0.000ms THRASHING count delay total delay average - 0 0 0ms + 0 0 0.000ms COMPACT count delay total delay average - 0 0 0ms + 0 0 0.000ms WPCOPY count delay total delay average 0 0 0ms -- cgit v1.2.3 From 7b32137bc027701cc9c57967af64fcdea0ef113b Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Mon, 27 Feb 2023 18:17:03 +0100 Subject: kcov: improve documentation Improve KCOV documentation: - Use KCOV instead of kcov, as the former is more widely-used. - Mention Clang in compiler requirements. - Use ``annotations`` for inline code. - Rework remote coverage collection documentation for better clarity. - Various smaller changes. [andreyknvl@google.com: v2] Link: https://lkml.kernel.org/r/583f41c49eef15210fa813e8229730d11427efa7.1677614637.git.andreyknvl@google.com [andreyknvl@google.com: fix ``annotation`` for KCOV_REMOTE_ENABLE] Link: https://lkml.kernel.org/r/72be5c215c275f35891229b90622ed859f196a46.1677684837.git.andreyknvl@google.com Link: https://lkml.kernel.org/r/0b5efd70e31bba7912cf9a6c951f0e76a8df27df.1677517724.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Dmitry Vyukov Reviewed-by: Bagas Sanjaya Cc: Alexander Potapenko Cc: Marco Elver Signed-off-by: Andrew Morton --- Documentation/dev-tools/kcov.rst | 169 +++++++++++++++++++++++---------------- 1 file changed, 102 insertions(+), 67 deletions(-) (limited to 'Documentation') diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst index d83c9ab49427..6611434e2dd2 100644 --- a/Documentation/dev-tools/kcov.rst +++ b/Documentation/dev-tools/kcov.rst @@ -1,42 +1,50 @@ -kcov: code coverage for fuzzing +KCOV: code coverage for fuzzing =============================== -kcov exposes kernel code coverage information in a form suitable for coverage- -guided fuzzing (randomized testing). Coverage data of a running kernel is -exported via the "kcov" debugfs file. Coverage collection is enabled on a task -basis, and thus it can capture precise coverage of a single system call. +KCOV collects and exposes kernel code coverage information in a form suitable +for coverage-guided fuzzing. Coverage data of a running kernel is exported via +the ``kcov`` debugfs file. Coverage collection is enabled on a task basis, and +thus KCOV can capture precise coverage of a single system call. -Note that kcov does not aim to collect as much coverage as possible. It aims -to collect more or less stable coverage that is function of syscall inputs. -To achieve this goal it does not collect coverage in soft/hard interrupts -and instrumentation of some inherently non-deterministic parts of kernel is -disabled (e.g. scheduler, locking). +Note that KCOV does not aim to collect as much coverage as possible. It aims +to collect more or less stable coverage that is a function of syscall inputs. +To achieve this goal, it does not collect coverage in soft/hard interrupts +(unless remove coverage collection is enabled, see below) and from some +inherently non-deterministic parts of the kernel (e.g. scheduler, locking). -kcov is also able to collect comparison operands from the instrumented code -(this feature currently requires that the kernel is compiled with clang). +Besides collecting code coverage, KCOV can also collect comparison operands. +See the "Comparison operands collection" section for details. + +Besides collecting coverage data from syscall handlers, KCOV can also collect +coverage for annotated parts of the kernel executing in background kernel +tasks or soft interrupts. See the "Remote coverage collection" section for +details. Prerequisites ------------- -Configure the kernel with:: +KCOV relies on compiler instrumentation and requires GCC 6.1.0 or later +or any Clang version supported by the kernel. - CONFIG_KCOV=y +Collecting comparison operands is supported with GCC 8+ or with Clang. -CONFIG_KCOV requires gcc 6.1.0 or later. +To enable KCOV, configure the kernel with:: -If the comparison operands need to be collected, set:: + CONFIG_KCOV=y + +To enable comparison operands collection, set:: CONFIG_KCOV_ENABLE_COMPARISONS=y -Profiling data will only become accessible once debugfs has been mounted:: +Coverage data only becomes accessible once debugfs has been mounted:: mount -t debugfs none /sys/kernel/debug Coverage collection ------------------- -The following program demonstrates coverage collection from within a test -program using kcov: +The following program demonstrates how to use KCOV to collect coverage for a +single syscall from within a test program: .. code-block:: c @@ -84,7 +92,7 @@ program using kcov: perror("ioctl"), exit(1); /* Reset coverage from the tail of the ioctl() call. */ __atomic_store_n(&cover[0], 0, __ATOMIC_RELAXED); - /* That's the target syscal call. */ + /* Call the target syscall call. */ read(-1, NULL, 0); /* Read number of PCs collected. */ n = __atomic_load_n(&cover[0], __ATOMIC_RELAXED); @@ -103,7 +111,7 @@ program using kcov: return 0; } -After piping through addr2line output of the program looks as follows:: +After piping through ``addr2line`` the output of the program looks as follows:: SyS_read fs/read_write.c:562 @@ -121,12 +129,13 @@ After piping through addr2line output of the program looks as follows:: fs/read_write.c:562 If a program needs to collect coverage from several threads (independently), -it needs to open /sys/kernel/debug/kcov in each thread separately. +it needs to open ``/sys/kernel/debug/kcov`` in each thread separately. The interface is fine-grained to allow efficient forking of test processes. -That is, a parent process opens /sys/kernel/debug/kcov, enables trace mode, -mmaps coverage buffer and then forks child processes in a loop. Child processes -only need to enable coverage (disable happens automatically on thread end). +That is, a parent process opens ``/sys/kernel/debug/kcov``, enables trace mode, +mmaps coverage buffer, and then forks child processes in a loop. The child +processes only need to enable coverage (it gets disabled automatically when +a thread exits). Comparison operands collection ------------------------------ @@ -205,52 +214,78 @@ Comparison operands collection is similar to coverage collection: return 0; } -Note that the kcov modes (coverage collection or comparison operands) are -mutually exclusive. +Note that the KCOV modes (collection of code coverage or comparison operands) +are mutually exclusive. Remote coverage collection -------------------------- -With KCOV_ENABLE coverage is collected only for syscalls that are issued -from the current process. With KCOV_REMOTE_ENABLE it's possible to collect -coverage for arbitrary parts of the kernel code, provided that those parts -are annotated with kcov_remote_start()/kcov_remote_stop(). - -This allows to collect coverage from two types of kernel background -threads: the global ones, that are spawned during kernel boot in a limited -number of instances (e.g. one USB hub_event() worker thread is spawned per -USB HCD); and the local ones, that are spawned when a user interacts with -some kernel interface (e.g. vhost workers); as well as from soft -interrupts. - -To enable collecting coverage from a global background thread or from a -softirq, a unique global handle must be assigned and passed to the -corresponding kcov_remote_start() call. Then a userspace process can pass -a list of such handles to the KCOV_REMOTE_ENABLE ioctl in the handles -array field of the kcov_remote_arg struct. This will attach the used kcov -device to the code sections, that are referenced by those handles. - -Since there might be many local background threads spawned from different -userspace processes, we can't use a single global handle per annotation. -Instead, the userspace process passes a non-zero handle through the -common_handle field of the kcov_remote_arg struct. This common handle gets -saved to the kcov_handle field in the current task_struct and needs to be -passed to the newly spawned threads via custom annotations. Those threads -should in turn be annotated with kcov_remote_start()/kcov_remote_stop(). - -Internally kcov stores handles as u64 integers. The top byte of a handle -is used to denote the id of a subsystem that this handle belongs to, and -the lower 4 bytes are used to denote the id of a thread instance within -that subsystem. A reserved value 0 is used as a subsystem id for common -handles as they don't belong to a particular subsystem. The bytes 4-7 are -currently reserved and must be zero. In the future the number of bytes -used for the subsystem or handle ids might be increased. - -When a particular userspace process collects coverage via a common -handle, kcov will collect coverage for each code section that is annotated -to use the common handle obtained as kcov_handle from the current -task_struct. However non common handles allow to collect coverage -selectively from different subsystems. +Besides collecting coverage data from handlers of syscalls issued from a +userspace process, KCOV can also collect coverage for parts of the kernel +executing in other contexts - so-called "remote" coverage. + +Using KCOV to collect remote coverage requires: + +1. Modifying kernel code to annotate the code section from where coverage + should be collected with ``kcov_remote_start`` and ``kcov_remote_stop``. + +2. Using ``KCOV_REMOTE_ENABLE`` instead of ``KCOV_ENABLE`` in the userspace + process that collects coverage. + +Both ``kcov_remote_start`` and ``kcov_remote_stop`` annotations and the +``KCOV_REMOTE_ENABLE`` ioctl accept handles that identify particular coverage +collection sections. The way a handle is used depends on the context where the +matching code section executes. + +KCOV supports collecting remote coverage from the following contexts: + +1. Global kernel background tasks. These are the tasks that are spawned during + kernel boot in a limited number of instances (e.g. one USB ``hub_event`` + worker is spawned per one USB HCD). + +2. Local kernel background tasks. These are spawned when a userspace process + interacts with some kernel interface and are usually killed when the process + exits (e.g. vhost workers). + +3. Soft interrupts. + +For #1 and #3, a unique global handle must be chosen and passed to the +corresponding ``kcov_remote_start`` call. Then a userspace process must pass +this handle to ``KCOV_REMOTE_ENABLE`` in the ``handles`` array field of the +``kcov_remote_arg`` struct. This will attach the used KCOV device to the code +section referenced by this handle. Multiple global handles identifying +different code sections can be passed at once. + +For #2, the userspace process instead must pass a non-zero handle through the +``common_handle`` field of the ``kcov_remote_arg`` struct. This common handle +gets saved to the ``kcov_handle`` field in the current ``task_struct`` and +needs to be passed to the newly spawned local tasks via custom kernel code +modifications. Those tasks should in turn use the passed handle in their +``kcov_remote_start`` and ``kcov_remote_stop`` annotations. + +KCOV follows a predefined format for both global and common handles. Each +handle is a ``u64`` integer. Currently, only the one top and the lower 4 bytes +are used. Bytes 4-7 are reserved and must be zero. + +For global handles, the top byte of the handle denotes the id of a subsystem +this handle belongs to. For example, KCOV uses ``1`` as the USB subsystem id. +The lower 4 bytes of a global handle denote the id of a task instance within +that subsystem. For example, each ``hub_event`` worker uses the USB bus number +as the task instance id. + +For common handles, a reserved value ``0`` is used as a subsystem id, as such +handles don't belong to a particular subsystem. The lower 4 bytes of a common +handle identify a collective instance of all local tasks spawned by the +userspace process that passed a common handle to ``KCOV_REMOTE_ENABLE``. + +In practice, any value can be used for common handle instance id if coverage +is only collected from a single userspace process on the system. However, if +common handles are used by multiple processes, unique instance ids must be +used for each process. One option is to use the process id as the common +handle instance id. + +The following program demonstrates using KCOV to collect coverage from both +local tasks spawned by the process and the global task that handles USB bus #1: .. code-block:: c -- cgit v1.2.3 From 0d828200ad56505a827610af876ca0b138b943a6 Mon Sep 17 00:00:00 2001 From: Matthieu Baerts Date: Mon, 3 Apr 2023 18:23:46 +0200 Subject: docs: process: allow Closes tags with links MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since v6.3, checkpatch.pl now complains about the use of "Closes:" tags followed by a link [1]. It also complains if a "Reported-by:" tag is followed by a "Closes:" one [2]. As detailed in the first patch, this "Closes:" tag is used for a bit of time, mainly by DRM and MPTCP subsystems. It is used by some bug trackers to automate the closure of issues when a patch is accepted. It is even planned to use this tag with bugzilla.kernel.org [3]. The first patch updates the documentation to explain what is this "Closes:" tag and how/when to use it. The second patch modifies checkpatch.pl to stop complaining about it. The DRM maintainers and their mailing list have been added in Cc as they are probably interested by these two patches as well. [1] https://lore.kernel.org/all/3b036087d80b8c0e07a46a1dbaaf4ad0d018f8d5.1674217480.git.linux@leemhuis.info/ [2] https://lore.kernel.org/all/bb5dfd55ea2026303ab2296f4a6df3da7dd64006.1674217480.git.linux@leemhuis.info/ [3] https://lore.kernel.org/linux-doc/20230315181205.f3av7h6owqzzw64p@meerkat.local/ This patch (of 5): Making sure a bug tracker is up to date is not an easy task. For example, a first version of a patch fixing a tracked issue can be sent a long time after having created the issue. But also, it can take some time to have this patch accepted upstream in its final form. When it is done, someone -- probably not the person who accepted the patch -- has to remember about closing the corresponding issue. This task of closing and tracking the patch can be done automatically by bug trackers like GitLab [1], GitHub [2] and hopefully soon [3] bugzilla.kernel.org when the appropriated tag is used. The two first ones accept multiple tags but it is probably better to pick one. According to commit 76f381bb77a0 ("checkpatch: warn when unknown tags are used for links"), the "Closes" tag seems to have been used in the past by a few people and it is supported by popular bug trackers. Here is how it has been used in the past: $ git log --no-merges --format=email -P --grep='^Closes: http' | \ grep '^Closes: http' | cut -d/ -f3-5 | sort | uniq -c | sort -rn 391 gitlab.freedesktop.org/drm/intel 79 github.com/multipath-tcp/mptcp_net-next 8 gitlab.freedesktop.org/drm/msm 3 gitlab.freedesktop.org/drm/amd 2 gitlab.freedesktop.org/mesa/mesa 1 patchwork.freedesktop.org/series/73320 1 gitlab.freedesktop.org/lima/linux 1 gitlab.freedesktop.org/drm/nouveau 1 github.com/ClangBuiltLinux/linux 1 bugzilla.netfilter.org/show_bug.cgi?id=1579 1 bugzilla.netfilter.org/show_bug.cgi?id=1543 1 bugzilla.netfilter.org/show_bug.cgi?id=1436 1 bugzilla.netfilter.org/show_bug.cgi?id=1427 1 bugs.debian.org/625804 Likely here, the "Closes" tag was only properly used with GitLab and GitHub. We can also see that it has been used quite a few times (and still used recently) and this is then not a "random tag that makes no sense" like it was the case with "BugLink" recently [4]. It has also been misused but that was a long time ago, when it was common to use many different random tags. checkpatch.pl script should then stop complaining about this "Closes" tag. As suggested by Thorsten [5], if this tag is accepted, it should first be described in the documentation. This is what is done here in this patch. To avoid confusion, the "Closes" should be used with any public bug report. No need to check if the underlying bug tracker supports automations. Having this tag with any kind of public bug reports allows bots like regzbot to clearly identify patches fixing a specific bug and avoid false-positives, e.g. patches mentioning it is related to an issue but not fixing it. As suggested by Thorsten [6] again, if we follow the same logic, the "Closes" tag should then be used after a "Reported-by" one. Note that thanks to this "Closes" tag, the mentioned bug trackers can also locate where a patch has been applied in different branches and repositories. If only the "Link" tag is used, the tracking can also be done but the ticket will not be closed and a manual operation will be needed. Also, these bug trackers have some safeguards: the closure is only done if a commit having the "Closes:" tag is applied in a specific branch. It will then not be closed if a random commit having the same tag is published elsewhere. Also in case of closure, a notification is sent to the owners. Link: https://lkml.kernel.org/r/20230314-doc-checkpatch-closes-tag-v4-0-d26d1fa66f9f@tessares.net Link: https://docs.gitlab.com/ee/user/project/issues/managing_issues.html#default-closing-pattern [1] Link: https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/using-keywords-in-issues-and-pull-requests [2] Link: https://lore.kernel.org/linux-doc/20230315181205.f3av7h6owqzzw64p@meerkat.local/ [3] Link: https://lore.kernel.org/all/CAHk-=wgs38ZrfPvy=nOwVkVzjpM3VFU1zobP37Fwd_h9iAD5JQ@mail.gmail.com/ [4] Link: https://lore.kernel.org/all/688cd6cb-90ab-6834-a6f5-97080e39ca8e@leemhuis.info/ [5] Link: https://lore.kernel.org/linux-doc/2194d19d-f195-1a1e-41fc-7827ae569351@leemhuis.info/ [6] Link: https://github.com/multipath-tcp/mptcp_net-next/issues/373 Link: https://lkml.kernel.org/r/20230314-doc-checkpatch-closes-tag-v4-1-d26d1fa66f9f@tessares.net Signed-off-by: Matthieu Baerts Suggested-by: Thorsten Leemhuis Acked-by: Konstantin Ryabitsev Acked-by: Joe Perches Cc: Andy Whitcroft Cc: Bagas Sanjaya Cc: Daniel Vetter Cc: David Airlie Cc: Dwaipayan Ray Cc: Jonathan Corbet Cc: Kai Wasserbäch Cc: Linus Torvalds Cc: Lukas Bulwahn Signed-off-by: Andrew Morton --- Documentation/process/5.Posting.rst | 22 +++++++++++++++++----- Documentation/process/submitting-patches.rst | 26 ++++++++++++++++++-------- 2 files changed, 35 insertions(+), 13 deletions(-) (limited to 'Documentation') diff --git a/Documentation/process/5.Posting.rst b/Documentation/process/5.Posting.rst index 7a670a075ab6..de4edd42d5c0 100644 --- a/Documentation/process/5.Posting.rst +++ b/Documentation/process/5.Posting.rst @@ -207,8 +207,8 @@ the patch:: Fixes: 1f2e3d4c5b6a ("The first line of the commit specified by the first 12 characters of its SHA-1 ID") Another tag is used for linking web pages with additional backgrounds or -details, for example a report about a bug fixed by the patch or a document -with a specification implemented by the patch:: +details, for example an earlier discussion which leads to the patch or a +document with a specification implemented by the patch:: Link: https://example.com/somewhere.html optional-other-stuff @@ -217,7 +217,17 @@ latest public review posting of the patch; often this is automatically done by tools like b4 or a git hook like the one described in 'Documentation/maintainer/configure-git.rst'. -A third kind of tag is used to document who was involved in the development of +If the URL points to a public bug report being fixed by the patch, use the +"Closes:" tag instead:: + + Closes: https://example.com/issues/1234 optional-other-stuff + +Some bug trackers have the ability to close issues automatically when a +commit with such a tag is applied. Some bots monitoring mailing lists can +also track such tags and take certain actions. Private bug trackers and +invalid URLs are forbidden. + +Another kind of tag is used to document who was involved in the development of the patch. Each of these uses this format:: tag: Full Name optional-other-stuff @@ -251,8 +261,10 @@ The tags in common use are: - Reported-by: names a user who reported a problem which is fixed by this patch; this tag is used to give credit to the (often underappreciated) people who test our code and let us know when things do not work - correctly. Note, this tag should be followed by a Link: tag pointing to the - report, unless the report is not available on the web. + correctly. Note, this tag should be followed by a Closes: tag pointing to + the report, unless the report is not available on the web. The Link: tag + can be used instead of Closes: if the patch fixes a part of the issue(s) + being reported. - Cc: the named person received a copy of the patch and had the opportunity to comment on it. diff --git a/Documentation/process/submitting-patches.rst b/Documentation/process/submitting-patches.rst index 828997bc9ff9..12d58ddc2b8a 100644 --- a/Documentation/process/submitting-patches.rst +++ b/Documentation/process/submitting-patches.rst @@ -113,11 +113,9 @@ there is no collision with your six-character ID now, that condition may change five years from now. If related discussions or any other background information behind the change -can be found on the web, add 'Link:' tags pointing to it. In case your patch -fixes a bug, for example, add a tag with a URL referencing the report in the -mailing list archives or a bug tracker; if the patch is a result of some -earlier mailing list discussion or something documented on the web, point to -it. +can be found on the web, add 'Link:' tags pointing to it. If the patch is a +result of some earlier mailing list discussions or something documented on the +web, point to it. When linking to mailing list archives, preferably use the lore.kernel.org message archiver service. To create the link URL, use the contents of the @@ -134,6 +132,16 @@ resources. In addition to giving a URL to a mailing list archive or bug, summarize the relevant points of the discussion that led to the patch as submitted. +In case your patch fixes a bug, use the 'Closes:' tag with a URL referencing +the report in the mailing list archives or a public bug tracker. For example:: + + Closes: https://example.com/issues/1234 + +Some bug trackers have the ability to close issues automatically when a +commit with such a tag is applied. Some bots monitoring mailing lists can +also track such tags and take certain actions. Private bug trackers and +invalid URLs are forbidden. + If your patch fixes a bug in a specific commit, e.g. you found an issue using ``git bisect``, please use the 'Fixes:' tag with the first 12 characters of the SHA-1 ID, and the one line summary. Do not split the tag across multiple @@ -498,9 +506,11 @@ Using Reported-by:, Tested-by:, Reviewed-by:, Suggested-by: and Fixes: The Reported-by tag gives credit to people who find bugs and report them and it hopefully inspires them to help us again in the future. The tag is intended for bugs; please do not use it to credit feature requests. The tag should be -followed by a Link: tag pointing to the report, unless the report is not -available on the web. Please note that if the bug was reported in private, then -ask for permission first before using the Reported-by tag. +followed by a Closes: tag pointing to the report, unless the report is not +available on the web. The Link: tag can be used instead of Closes: if the patch +fixes a part of the issue(s) being reported. Please note that if the bug was +reported in private, then ask for permission first before using the Reported-by +tag. A Tested-by: tag indicates that the patch has been successfully tested (in some environment) by the person named. This tag informs maintainers that -- cgit v1.2.3 From a3b2aeac9d154e5e15ddbf19de934c0c606b6acd Mon Sep 17 00:00:00 2001 From: Yang Yang Date: Sat, 8 Apr 2023 17:28:35 +0800 Subject: delayacct: track delays from IRQ/SOFTIRQ Delay accounting does not track the delay of IRQ/SOFTIRQ. While IRQ/SOFTIRQ could have obvious impact on some workloads productivity, such as when workloads are running on system which is busy handling network IRQ/SOFTIRQ. Get the delay of IRQ/SOFTIRQ could help users to reduce such delay. Such as setting interrupt affinity or task affinity, using kernel thread for NAPI etc. This is inspired by "sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure"[1]. Also fix some code indent problems of older code. And update tools/accounting/getdelays.c: / # ./getdelays -p 156 -di print delayacct stats ON printing IO accounting PID 156 CPU count real total virtual total delay total delay average 15 15836008 16218149 275700790 18.380ms IO count delay total delay average 0 0 0.000ms SWAP count delay total delay average 0 0 0.000ms RECLAIM count delay total delay average 0 0 0.000ms THRASHING count delay total delay average 0 0 0.000ms COMPACT count delay total delay average 0 0 0.000ms WPCOPY count delay total delay average 36 7586118 0.211ms IRQ count delay total delay average 42 929161 0.022ms [1] commit 52b1364ba0b1("sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure") Link: https://lkml.kernel.org/r/202304081728353557233@zte.com.cn Signed-off-by: Yang Yang Cc: Jiang Xuexin Cc: wangyong Cc: junhua huang Cc: Balbir Singh Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Juri Lelli Cc: Peter Zijlstra Signed-off-by: Andrew Morton --- Documentation/accounting/delay-accounting.rst | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst index 79f537c9f160..f61c01fc376e 100644 --- a/Documentation/accounting/delay-accounting.rst +++ b/Documentation/accounting/delay-accounting.rst @@ -16,6 +16,7 @@ d) memory reclaim e) thrashing f) direct compact g) write-protect copy +h) IRQ/SOFTIRQ and makes these statistics available to userspace through the taskstats interface. @@ -49,7 +50,7 @@ this structure. See for a description of the fields pertaining to delay accounting. It will generally be in the form of counters returning the cumulative delay seen for cpu, sync block I/O, swapin, memory reclaim, thrash page -cache, direct compact, write-protect copy etc. +cache, direct compact, write-protect copy, IRQ/SOFTIRQ etc. Taking the difference of two successive readings of a given counter (say cpu_delay_total) for a task will give the delay @@ -118,7 +119,9 @@ Get sum of delays, since system boot, for all pids with tgid 5:: 0 0 0.000ms COMPACT count delay total delay average 0 0 0.000ms - WPCOPY count delay total delay average + WPCOPY count delay total delay average + 0 0 0.000ms + IRQ count delay total delay average 0 0 0.000ms Get IO accounting for pid 1, it works only with -p:: -- cgit v1.2.3 From 522dc4e5f51e3d51c4ff55ad1c725d12176b71ea Mon Sep 17 00:00:00 2001 From: Chunguang Wu Date: Sun, 16 Apr 2023 13:24:04 +0800 Subject: fs/proc: add Kthread flag to /proc/$pid/status The command `ps -ef ` and `top -c` mark kernel thread by '[' and ']', but sometimes the result is not correct. The task->flags in /proc/$pid/stat is good, but we need remember the value of PF_KTHREAD is 0x00200000 and convert dec to hex. If we have no binary program and shell script which read /proc/$pid/stat, we can know it directly by `cat /proc/$pid/status`. Link: https://lkml.kernel.org/r/20230416052404.2920-1-fullspring2018@gmail.com Signed-off-by: Chunguang Wu Reviewed-by: Randy Dunlap Cc: Alexey Dobriyan Cc: Jonathan Corbet Signed-off-by: Andrew Morton --- Documentation/filesystems/proc.rst | 2 ++ 1 file changed, 2 insertions(+) (limited to 'Documentation') diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 9d5fd9424e8b..8a563684586c 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -179,6 +179,7 @@ read the file /proc/PID/status:: Gid: 100 100 100 100 FDSize: 256 Groups: 100 14 16 + Kthread: 0 VmPeak: 5004 kB VmSize: 5004 kB VmLck: 0 kB @@ -256,6 +257,7 @@ It's slow but very precise. NSpid descendant namespace process ID hierarchy NSpgid descendant namespace process group ID hierarchy NSsid descendant namespace session ID hierarchy + Kthread kernel thread flag, 1 is yes, 0 is no VmPeak peak virtual memory size VmSize total program size VmLck locked memory size -- cgit v1.2.3