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Message-ID: <20250907001101305vrTGnXaRNvtmsGkp-Ljk_@zte.com.cn>
Date: Sun, 7 Sep 2025 00:11:01 +0800 (CST)
From: <fan.yu9@....com.cn>
To: <akpm@...ux-foundation.org>, <wang.yaxin@....com.cn>, <corbet@....net>
Cc: <linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<fan.yu9@....com.cn>, <wang.yaxin@....com.cn>, <xu.xin16@....com.cn>,
<yang.yang29@....com.cn>
Subject: [PATCHv2 linux-next 0/5] tools/delaytop: implement real-time keyboard interaction support
From: Fan Yu <fan.yu9@....com.cn>
Current Limitations
===================
The current delaytop implementation has two main limitations:
1) Static sorting only by CPU delay
Forcing users to restart with different parameters to analyze
other resource bottlenecks.
2) Memory delay information is always expanded
Causing information overload when only high-level memory pressure
monitoring is needed.
Improvements
============
1) Implemented dynamic sorting capability
- Interactive key 'o' triggers sort mode.
- Supports sorting by CPU/IO/Memory/IRQ delays.
- Memory subcategories available in verbose mode.
* c - CPU delay (default)
* i - IO delay
* m - Total memory delay
* q - IRQ delay
* s/r/t/p/w - Memory subcategories (in verbose mode)
2) Added memory display modes
- Compact view (default): shows aggregated memory delays.
- Verbose view ('M' key): breaks down into memory sub-delays.
* SWAP - swapin delays
* RCL - freepages reclaim delays
* THR - thrashing delays
* CMP - compaction delays
* WP - write-protect copy delays
Practical benefits
==================
1) Dynamic Sorting for Real-Time Bottleneck Detection
System administrators can now dynamically change sorting to identify
different types of resource bottlenecks without restarting.
2) Enhanced Usability with On-Screen Keybindings
More intuitive interactive usage with on-screen keybindings help.
Reduced screen clutter when only memory overview is needed.
Use Case
========
# ./delaytop
System Pressure Information: (avg10/avg60vg300/total)
CPU some: 0.0%/ 0.0%/ 0.0%/ 106817(ms)
CPU full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
Memory full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
Memory some: 0.0%/ 0.0%/ 0.0%/ 0(ms)
IO full: 0.0%/ 0.0%/ 0.0%/ 2245(ms)
IO some: 0.0%/ 0.0%/ 0.0%/ 2791(ms)
IRQ full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
[o]sort [M]memverbose [q]quit
Top 20 processes (sorted by cpu delay):
PID TGID COMMAND CPU(ms) IO(ms) IRQ(ms) MEM(ms)
------------------------------------------------------------------------
110 110 kworker/15:0H-s 27.91 0.00 0.00 0.00
57 57 cpuhp/7 3.18 0.00 0.00 0.00
99 99 cpuhp/14 2.97 0.00 0.00 0.00
51 51 cpuhp/6 0.90 0.00 0.00 0.00
44 44 kworker/4:0H-sy 0.80 0.00 0.00 0.00
76 76 idle_inject/10 0.31 0.00 0.00 0.00
100 100 idle_inject/14 0.30 0.00 0.00 0.00
1309 1309 systemsettings 0.29 0.00 0.00 0.00
60 60 ksoftirqd/7 0.28 0.00 0.00 0.00
45 45 cpuhp/5 0.22 0.00 0.00 0.00
63 63 cpuhp/8 0.20 0.00 0.00 0.00
87 87 cpuhp/12 0.18 0.00 0.00 0.00
93 93 cpuhp/13 0.17 0.00 0.00 0.00
1265 1265 acpid 0.17 0.00 0.00 0.00
1552 1552 sshd 0.17 0.00 0.00 0.00
2584 2584 sddm-helper 0.16 0.00 0.00 0.00
1284 1284 rtkit-daemon 0.15 0.00 0.00 0.00
1326 1326 nde-netfilter 0.14 0.00 0.00 0.00
27 27 cpuhp/2 0.13 0.00 0.00 0.00
631 631 kworker/11:2-rc 0.11 0.00 0.00 0.00
# ./delaytop -M
System Pressure Information: (avg10/avg60vg300/total)
CPU some: 0.0%/ 0.0%/ 0.0%/ 106827(ms)
CPU full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
Memory full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
Memory some: 0.0%/ 0.0%/ 0.0%/ 0(ms)
IO full: 0.0%/ 0.0%/ 0.0%/ 2245(ms)
IO some: 0.0%/ 0.0%/ 0.0%/ 2791(ms)
IRQ full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
[o]sort [M]memverbose [q]quit
Top 20 processes (sorted by mem delay):
PID TGID COMMAND MEM(ms) SWAP(ms) RCL(ms) THR(ms) CMP(ms) WP(ms)
------------------------------------------------------------------------------------------
121732 121732 delaytop 0.01 0.00 0.00 0.00 0.00 0.01
95876 95876 top 0.00 0.00 0.00 0.00 0.00 0.00
121641 121641 systemd-userwor 0.00 0.00 0.00 0.00 0.00 0.00
121693 121693 systemd-userwor 0.00 0.00 0.00 0.00 0.00 0.00
121661 121661 systemd-userwor 0.00 0.00 0.00 0.00 0.00 0.00
1 1 systemd 0.00 0.00 0.00 0.00 0.00 0.00
2 2 kthreadd 0.00 0.00 0.00 0.00 0.00 0.00
3 3 pool_workqueue_ 0.00 0.00 0.00 0.00 0.00 0.00
4 4 kworker/R-rcu_g 0.00 0.00 0.00 0.00 0.00 0.00
5 5 kworker/R-rcu_p 0.00 0.00 0.00 0.00 0.00 0.00
6 6 kworker/R-slub_ 0.00 0.00 0.00 0.00 0.00 0.00
7 7 kworker/R-netns 0.00 0.00 0.00 0.00 0.00 0.00
9 9 kworker/0:0H-sy 0.00 0.00 0.00 0.00 0.00 0.00
11 11 kworker/u32:0-n 0.00 0.00 0.00 0.00 0.00 0.00
12 12 kworker/R-mm_pe 0.00 0.00 0.00 0.00 0.00 0.00
13 13 rcu_tasks_kthre 0.00 0.00 0.00 0.00 0.00 0.00
14 14 rcu_tasks_rude_ 0.00 0.00 0.00 0.00 0.00 0.00
15 15 rcu_tasks_trace 0.00 0.00 0.00 0.00 0.00 0.00
16 16 ksoftirqd/0 0.00 0.00 0.00 0.00 0.00 0.00
17 17 rcu_preempt 0.00 0.00 0.00 0.00 0.00 0.00
When psi is not enabled:
# ./delaytop
System Pressure Information: (avg10/avg60vg300/total)
PSI not found: check if psi=1 enabled in cmdline
v2->v1:
Some fixes according to:
https://lore.kernel.org/all/202509021454480003xS5M8WmAIQT2F_IiSd3p@zte.com.cn/
https://lore.kernel.org/all/202509021138097501cXkw4xiXiYSWRs8thevi@zte.com.cn/
1. Refactored delay sorting and view display logic for better extensibility
2. Optimized memory delay verbose view (exclude CPU/IRQ/IO delays)
3. Added user notice for PSI configuration when not enabled
4. Updated documentation covering all new interactive features
Fan Yu (5):
tools/delaytop: add flexible sorting by delay field
tools/delaytop: add memory verbose mode support
tools/delaytop: add interactive mode with keyboard controls
tools/delaytop: Improve error handling for missing PSI support
docs: update delaytop documentation for new interactive features
Documentation/accounting/delay-accounting.rst | 91 ++-
tools/accounting/delaytop.c | 571 +++++++++++++-----
2 files changed, 485 insertions(+), 177 deletions(-)
--
2.25.1
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