kernel.git/Documentation/accounting, branch linux-6.15.y

Merge tag 'mm-nonmm-stable-2025-01-24-23-16' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-01-27T01:50:53Z

Pull non-MM updates from Andrew Morton: "Mainly individually changelogged singleton patches. The patch series in this pull are: - "lib min_heap: Improve min_heap safety, testing, and documentation" from Kuan-Wei Chiu provides various tightenings to the min_heap library code - "xarray: extract __xa_cmpxchg_raw" from Tamir Duberstein preforms some cleanup and Rust preparation in the xarray library code - "Update reference to include/asm-" from Geert Uytterhoeven fixes pathnames in some code comments - "Converge on using secs_to_jiffies()" from Easwar Hariharan uses the new secs_to_jiffies() in various places where that is appropriate - "ocfs2, dlmfs: convert to the new mount API" from Eric Sandeen switches two filesystems to the new mount API - "Convert ocfs2 to use folios" from Matthew Wilcox does that - "Remove get_task_comm() and print task comm directly" from Yafang Shao removes now-unneeded calls to get_task_comm() in various places - "squashfs: reduce memory usage and update docs" from Phillip Lougher implements some memory savings in squashfs and performs some maintainability work - "lib: clarify comparison function requirements" from Kuan-Wei Chiu tightens the sort code's behaviour and adds some maintenance work - "nilfs2: protect busy buffer heads from being force-cleared" from Ryusuke Konishi fixes an issues in nlifs when the fs is presented with a corrupted image - "nilfs2: fix kernel-doc comments for function return values" from Ryusuke Konishi fixes some nilfs kerneldoc - "nilfs2: fix issues with rename operations" from Ryusuke Konishi addresses some nilfs BUG_ONs which syzbot was able to trigger - "minmax.h: Cleanups and minor optimisations" from David Laight does some maintenance work on the min/max library code - "Fixes and cleanups to xarray" from Kemeng Shi does maintenance work on the xarray library code" * tag 'mm-nonmm-stable-2025-01-24-23-16' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (131 commits) ocfs2: use str_yes_no() and str_no_yes() helper functions include/linux/lz4.h: add some missing macros Xarray: use xa_mark_t in xas_squash_marks() to keep code consistent Xarray: remove repeat check in xas_squash_marks() Xarray: distinguish large entries correctly in xas_split_alloc() Xarray: move forward index correctly in xas_pause() Xarray: do not return sibling entries from xas_find_marked() ipc/util.c: complete the kernel-doc function descriptions gcov: clang: use correct function param names latencytop: use correct kernel-doc format for func params minmax.h: remove some #defines that are only expanded once minmax.h: simplify the variants of clamp() minmax.h: move all the clamp() definitions after the min/max() ones minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp() minmax.h: reduce the #define expansion of min(), max() and clamp() minmax.h: update some comments minmax.h: add whitespace around operators and after commas nilfs2: do not update mtime of renamed directory that is not moved nilfs2: handle errors that nilfs_prepare_chunk() may return CREDITS: fix spelling mistake ...

delayacct: add delay min to record delay peak

2025-01-13T04:21:16Z

Delay accounting can now calculate the average delay of processes, detect the overall system load, and also record the 'delay max' to identify potential abnormal delays. However, 'delay min' can help us identify another useful delay peak. By comparing the difference between 'delay max' and 'delay min', we can understand the optimization space for latency, providing a reference for the optimization of latency performance. Use case ========= bash-4.4# ./getdelays -d -t 242 print delayacct stats ON TGID 242 CPU count real total virtual total delay total delay average delay max delay min 39 156000000 156576579 2111069 0.054ms 0.212296ms 0.031307ms IO count delay total delay average delay max delay min 0 0 0.000ms 0.000000ms 0.000000ms SWAP count delay total delay average delay max delay min 0 0 0.000ms 0.000000ms 0.000000ms RECLAIM count delay total delay average delay max delay min 0 0 0.000ms 0.000000ms 0.000000ms THRASHING count delay total delay average delay max delay min 0 0 0.000ms 0.000000ms 0.000000ms COMPACT count delay total delay average delay max delay min 0 0 0.000ms 0.000000ms 0.000000ms WPCOPY count delay total delay average delay max delay min 156 11215873 0.072ms 0.207403ms 0.033913ms IRQ count delay total delay average delay max delay min 0 0 0.000ms 0.000000ms 0.000000ms Link: https://lkml.kernel.org/r/20241220173105906EOdsPhzjMLYNJJBqgz1ga@zte.com.cn Co-developed-by: Wang Yong Signed-off-by: Wang Yong Co-developed-by: xu xin Signed-off-by: xu xin Signed-off-by: Wang Yaxin Co-developed-by: Kun Jiang Signed-off-by: Kun Jiang Cc: Balbir Singh Cc: David Hildenbrand Cc: Fan Yu Cc: Peilin He Cc: tuqiang Cc: ye xingchen Cc: Yunkai Zhang Signed-off-by: Andrew Morton

delayacct: add delay max to record delay peak

2025-01-13T04:20:59Z

Introduce the use cases of delay max, which can help quickly detect potential abnormal delays in the system and record the types and specific details of delay spikes. Problem ======== Delay accounting can track the average delay of processes to show system workload. However, when a process experiences a significant delay, maybe a delay spike, which adversely affects performance, getdelays can only display the average system delay over a period of time. Yet, average delay is unhelpful for diagnosing delay peak. It is not even possible to determine which type of delay has spiked, as this information might be masked by the average delay. Solution ========= the 'delay max' can display delay peak since the system's startup, which can record potential abnormal delays over time, including the type of delay and the maximum delay. This is helpful for quickly identifying crash caused by delay. Use case ========= bash# ./getdelays -d -p 244 print delayacct stats ON PID 244 CPU count real total virtual total delay total delay average delay max 68 192000000 213676651 705643 0.010ms 0.306381ms IO count delay total delay average delay max 0 0 0.000ms 0.000000ms SWAP count delay total delay average delay max 0 0 0.000ms 0.000000ms RECLAIM count delay total delay average delay max 0 0 0.000ms 0.000000ms THRASHING count delay total delay average delay max 0 0 0.000ms 0.000000ms COMPACT count delay total delay average delay max 0 0 0.000ms 0.000000ms WPCOPY count delay total delay average delay max 235 15648284 0.067ms 0.263842ms IRQ count delay total delay average delay max 0 0 0.000ms 0.000000ms [wang.yaxin@zte.com.cn: update docs and fix some spelling errors] Link: https://lkml.kernel.org/r/20241213192700771XKZ8H30OtHSeziGqRVMs0@zte.com.cn Link: https://lkml.kernel.org/r/20241203164848805CS62CQPQWG9GLdQj2_BxS@zte.com.cn Co-developed-by: Wang Yong Signed-off-by: Wang Yong Co-developed-by: xu xin Signed-off-by: xu xin Co-developed-by: Wang Yaxin Signed-off-by: Wang Yaxin Signed-off-by: Kun Jiang Cc: Balbir Singh Cc: David Hildenbrand Cc: Fan Yu Cc: Peilin He Cc: tuqiang Cc: Yang Yang Cc: ye xingchen Cc: Yunkai Zhang Signed-off-by: Andrew Morton

Documentation/accounting: Fix typo in taskstats-struct.rst

2024-12-13T15:44:29Z

Corrected a typo in the 'taskstats-struct.rst' documentation. The macro name 'TAKSTATS_VERSION' was mistakenly mentioned instead of the correct 'TASKSTATS_VERSION'. The corrected line now references the proper macro 'TASKSTATS_VERSION', defined in ''. Signed-off-by: Sarveshwaar SS Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20241208083320.16190-1-sarvesh20123@gmail.com

docs: psi: use correct config name

2023-07-31T15:54:17Z

Commit 2ce7135adc9a ("psi: cgroup support") adds documentation which refers to CONFIG_CGROUP, but the correct name is CONFIG_CGROUPS. Correct the reference to CONFIG_CGROUPS. Co-developed-by: Sabina Trendota Signed-off-by: Sabina Trendota Signed-off-by: Ramazan Safiullin Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20230728115600.231068-1-ram.safiullin2001@gmail.com

Merge tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-04-28T21:53:30Z

Pull scheduler updates from Ingo Molnar: - Allow unprivileged PSI poll()ing - Fix performance regression introduced by mm_cid - Improve livepatch stalls by adding livepatch task switching to cond_resched(). This resolves livepatching busy-loop stalls with certain CPU-bound kthreads - Improve sched_move_task() performance on autogroup configs - On core-scheduling CPUs, avoid selecting throttled tasks to run - Misc cleanups, fixes and improvements * tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/clock: Fix local_clock() before sched_clock_init() sched/rt: Fix bad task migration for rt tasks sched: Fix performance regression introduced by mm_cid sched/core: Make sched_dynamic_mutex static sched/psi: Allow unprivileged polling of N*2s period sched/psi: Extract update_triggers side effect sched/psi: Rename existing poll members in preparation sched/psi: Rearrange polling code in preparation sched/fair: Fix inaccurate tally of ttwu_move_affine vhost: Fix livepatch timeouts in vhost_worker() livepatch,sched: Add livepatch task switching to cond_resched() livepatch: Skip task_call_func() for current task livepatch: Convert stack entries array to percpu sched: Interleave cfs bandwidth timers for improved single thread performance at low utilization sched/core: Reduce cost of sched_move_task when config autogroup sched/core: Avoid selecting the task that is throttled to run when core-sched enable sched/topology: Make sched_energy_mutex,update static

delayacct: track delays from IRQ/SOFTIRQ

2023-04-18T23:39:34Z

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

delayacct: improve the average delay precision of getdelay tool to microsecond

2023-04-08T20:45:36Z

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

sched/psi: Allow unprivileged polling of N*2s period

2023-04-05T07:58:50Z

PSI offers 2 mechanisms to get information about a specific resource pressure. One is reading from /proc/pressure/, which gives average pressures aggregated every 2s. The other is creating a pollable fd for a specific resource and cgroup. The trigger creation requires CAP_SYS_RESOURCE, and gives the possibility to pick specific time window and threshold, spawing an RT thread to aggregate the data. Systemd would like to provide containers the option to monitor pressure on their own cgroup and sub-cgroups. For example, if systemd launches a container that itself then launches services, the container should have the ability to poll() for pressure in individual services. But neither the container nor the services are privileged. This patch implements a mechanism to allow unprivileged users to create pressure triggers. The difference with privileged triggers creation is that unprivileged ones must have a time window that's a multiple of 2s. This is so that we can avoid unrestricted spawning of rt threads, and use instead the same aggregation mechanism done for the averages, which runs independently of any triggers. Suggested-by: Johannes Weiner Signed-off-by: Domenico Cerasuolo Signed-off-by: Peter Zijlstra (Intel) Acked-by: Johannes Weiner Link: https://lore.kernel.org/r/20230330105418.77061-5-cerasuolodomenico@gmail.com

filemap: make the accounting of thrashing more consistent

2022-09-27T02:46:06Z

Once upon a time, we only support accounting thrashing of page cache. Then Joonsoo introduced workingset detection for anonymous pages and we gained the ability to account thrashing of them[1]. So let delayacct account both the thrashing of page cache and anonymous pages, this could make the codes more consistent and simpler. [1] commit aae466b0052e ("mm/swap: implement workingset detection for anonymous LRU") Link: https://lkml.kernel.org/r/20220805033838.1714674-1-yang.yang29@zte.com.cn Signed-off-by: Yang Yang Signed-off-by: CGEL ZTE Acked-by: Joonsoo Kim Cc: Balbir Singh Cc: Jonathan Corbet Cc: Matthew Wilcox (Oracle) Cc: Yang Yang Cc: David Hildenbrand Signed-off-by: Andrew Morton