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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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docs: update docs after introducing delaytop

The "getdelays" can only display the latency of a single task by
specifying a PID, we introduce the "delaytop" with the following
capabilities:

1. system view: monitors latency metrics (CPU, I/O, memory, IRQ, etc.)
for all system processes

2. supports field-based sorting (e.g., default sort by CPU latency in
descending order)

3. dynamic interactive interface: focus on specific processes with
--pid; limit displayed entries with --processes 20; control monitoring
duration with --iterations;

Link: https://lkml.kernel.org/r/2025071013514177028RdjISjqeIOnTCRvGAwy@zte.com.cn
Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
Signed-off-by: Wang Yaxin <wang.yaxin@zte.com.cn>
Signed-off-by: Jiang Kun <jiang.kun2@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Peilin He <he.peilin@zte.com.cn>
Cc: Qiang Tu <tu.qiang35@zte.com.cn>
Cc: wangyong <wang.yong12@zte.com.cn>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Yunkai Zhang <zhang.yunkai@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

authored by

Wang Yaxin and committed by
Andrew Morton 320bf170 6b47c9f8

+47
+47
Documentation/accounting/delay-accounting.rst
··· 131 131 linuxrc: read=65536, write=0, cancelled_write=0 132 132 133 133 The above command can be used with -v to get more debug information. 134 + 135 + After the system starts, use `delaytop` to get the Top-N high-latency tasks. 136 + this tool supports sorting by CPU latency in descending order by default, 137 + displays the top 20 high-latency tasks by default, and refreshes the latency 138 + data every 2 seconds by default. 139 + 140 + Get Top-N tasks delay, since system boot:: 141 + 142 + bash# ./delaytop 143 + Top 20 processes (sorted by CPU delay): 144 + 145 + PID TGID COMMAND CPU(ms) IO(ms) SWAP(ms) RCL(ms) THR(ms) CMP(ms) WP(ms) IRQ(ms) 146 + --------------------------------------------------------------------------------------------- 147 + 32 32 kworker/2:0H-sy 23.65 0.00 0.00 0.00 0.00 0.00 0.00 0.00 148 + 497 497 kworker/R-scsi_ 1.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 149 + 495 495 kworker/R-scsi_ 1.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 150 + 494 494 scsi_eh_0 1.12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 151 + 485 485 kworker/R-ata_s 0.90 0.00 0.00 0.00 0.00 0.00 0.00 0.00 152 + 574 574 kworker/R-kdmfl 0.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 153 + 34 34 idle_inject/3 0.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 154 + 1123 1123 nde-netfilter 0.28 0.00 0.00 0.00 0.00 0.00 0.00 0.00 155 + 60 60 ksoftirqd/7 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 156 + 114 114 kworker/0:2-cgr 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 157 + 496 496 scsi_eh_1 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 158 + 51 51 cpuhp/6 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 159 + 1667 1667 atd 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 160 + 45 45 cpuhp/5 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00 161 + 1102 1102 nde-backupservi 0.22 0.00 0.00 0.00 0.00 0.00 0.00 0.00 162 + 1098 1098 systemsettings 0.21 0.00 0.00 0.00 0.00 0.00 0.00 0.00 163 + 1100 1100 audit-monitor 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 164 + 53 53 migration/6 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 165 + 1482 1482 sshd 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 166 + 39 39 cpuhp/4 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 167 + 168 + Dynamic interactive interface of delaytop:: 169 + 170 + # ./delaytop -p pid 171 + Print delayacct stats 172 + 173 + # ./delaytop -P num 174 + Display the top N tasks 175 + 176 + # ./delaytop -n num 177 + Set delaytop refresh frequency (num times) 178 + 179 + # ./delaytop -d secs 180 + Specify refresh interval as secs