| From: Wang Yaxin <wang.yaxin@zte.com.cn> |
| Subject: docs: update docs after introducing delaytop |
| Date: Thu, 10 Jul 2025 13:51:41 +0800 (CST) |
| |
| 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> |
| --- |
| |
| Documentation/accounting/delay-accounting.rst | 47 ++++++++++++++++ |
| 1 file changed, 47 insertions(+) |
| |
| --- a/Documentation/accounting/delay-accounting.rst~docs-update-docs-after-introducing-delaytop |
| +++ a/Documentation/accounting/delay-accounting.rst |
| @@ -131,3 +131,50 @@ Get IO accounting for pid 1, it works on |
| linuxrc: read=65536, write=0, cancelled_write=0 |
| |
| The above command can be used with -v to get more debug information. |
| + |
| +After the system starts, use `delaytop` to get the Top-N high-latency tasks. |
| +this tool supports sorting by CPU latency in descending order by default, |
| +displays the top 20 high-latency tasks by default, and refreshes the latency |
| +data every 2 seconds by default. |
| + |
| +Get Top-N tasks delay, since system boot:: |
| + |
| + bash# ./delaytop |
| + Top 20 processes (sorted by CPU delay): |
| + |
| + PID TGID COMMAND CPU(ms) IO(ms) SWAP(ms) RCL(ms) THR(ms) CMP(ms) WP(ms) IRQ(ms) |
| + --------------------------------------------------------------------------------------------- |
| + 32 32 kworker/2:0H-sy 23.65 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 497 497 kworker/R-scsi_ 1.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 495 495 kworker/R-scsi_ 1.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 494 494 scsi_eh_0 1.12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 485 485 kworker/R-ata_s 0.90 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 574 574 kworker/R-kdmfl 0.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 34 34 idle_inject/3 0.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 1123 1123 nde-netfilter 0.28 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 60 60 ksoftirqd/7 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 114 114 kworker/0:2-cgr 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 496 496 scsi_eh_1 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 51 51 cpuhp/6 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 1667 1667 atd 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 45 45 cpuhp/5 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 1102 1102 nde-backupservi 0.22 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 1098 1098 systemsettings 0.21 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 1100 1100 audit-monitor 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 53 53 migration/6 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 1482 1482 sshd 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + 39 39 cpuhp/4 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 |
| + |
| +Dynamic interactive interface of delaytop:: |
| + |
| + # ./delaytop -p pid |
| + Print delayacct stats |
| + |
| + # ./delaytop -P num |
| + Display the top N tasks |
| + |
| + # ./delaytop -n num |
| + Set delaytop refresh frequency (num times) |
| + |
| + # ./delaytop -d secs |
| + Specify refresh interval as secs |
| _ |
