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Message-ID: <20250907001457696qAqUGGkV1VfEO6OkVMovW@zte.com.cn>
Date: Sun, 7 Sep 2025 00:14:57 +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>,
<xu.xin16@....com.cn>, <yang.yang29@....com.cn>
Subject: [PATCHv2 linux-next 5/5] docs: update delaytop documentation for new interactive features
From: Fan Yu <fan.yu9@....com.cn>
This commit updates the delaytop documentation to reflect the newly
added features:
1) Added comprehensive description of interactive keyboard controls
2) Documented all available sort fields
3) Added examples for advanced usage scenarios
4) Included PSI availability note
Signed-off-by: Fan Yu <fan.yu9@....com.cn>
---
Documentation/accounting/delay-accounting.rst | 91 ++++++++++++-------
1 file changed, 58 insertions(+), 33 deletions(-)
diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst
index 8ccc5af5ea1e..7cca536d2c4c 100644
--- a/Documentation/accounting/delay-accounting.rst
+++ b/Documentation/accounting/delay-accounting.rst
@@ -134,47 +134,72 @@ The above command can be used with -v to get more debug information.
After the system starts, use `delaytop` to get the system-wide delay information,
which includes system-wide PSI information and Top-N high-latency tasks.
+Note: PSI support requires `CONFIG_PSI=y` and `psi=1` for full functionality.
-`delaytop` 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.
+`delaytop` is an interactive tool for monitoring system pressure and task delays.
+It supports multiple sorting options, display modes, and real-time keyboard controls.
-Get PSI information and Top-N tasks delay, since system boot::
+Basic usage with default settings (sorts by CPU delay, shows top 20 tasks, refreshes every 2 seconds)::
bash# ./delaytop
- System Pressure Information: (avg10/avg60/avg300/total)
- CPU some: 0.0%/ 0.0%/ 0.0%/ 345(ms)
+ System Pressure Information: (avg10/avg60vg300/total)
+ CPU some: 0.0%/ 0.0%/ 0.0%/ 106137(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%/ 65(ms)
- IO some: 0.0%/ 0.0%/ 0.0%/ 79(ms)
+ IO full: 0.0%/ 0.0%/ 0.0%/ 2240(ms)
+ IO some: 0.0%/ 0.0%/ 0.0%/ 2783(ms)
IRQ full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
- 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)
- ----------------------------------------------------------------------------------------------
- 161 161 zombie_memcg_re 1.40 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 130 130 blkcg_punt_bio 1.37 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 444 444 scsi_tmf_0 0.73 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1280 1280 rsyslogd 0.53 0.04 0.00 0.00 0.00 0.00 0.00 0.00
- 12 12 ksoftirqd/0 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1277 1277 nbd-server 0.44 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 308 308 kworker/2:2-sys 0.41 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 55 55 netns 0.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1187 1187 acpid 0.31 0.03 0.00 0.00 0.00 0.00 0.00 0.00
- 6184 6184 kworker/1:2-sys 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 186 186 kaluad 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 18 18 ksoftirqd/1 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 185 185 kmpath_rdacd 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 190 190 kstrp 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 2759 2759 agetty 0.20 0.03 0.00 0.00 0.00 0.00 0.00 0.00
- 1190 1190 kworker/0:3-sys 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1272 1272 sshd 0.15 0.04 0.00 0.00 0.00 0.00 0.00 0.00
- 1156 1156 license 0.15 0.11 0.00 0.00 0.00 0.00 0.00 0.00
- 134 134 md 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 6142 6142 kworker/3:2-xfs 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00
-
-Dynamic interactive interface of delaytop::
+ [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
+ 60 60 ksoftirqd/7 0.74 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
+ 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
+
+Interactive keyboard controls during runtime::
+
+ o - Select sort field (CPU, IO, IRQ, Memory, etc.)
+ M - Toggle display mode (Default/Memory Verbose)
+ q - Quit
+
+Available sort fields(use -s/--sort or interactive command)::
+
+ cpu(c) - CPU delay
+ blkio(i) - I/O delay
+ irq(q) - IRQ delay
+ mem(m) - Total memory delay
+ swapin(s) - Swapin delay (memory verbose mode only)
+ freepages(r) - Freepages reclaim delay (memory verbose mode only)
+ thrashing(t) - Thrashing delay (memory verbose mode only)
+ compact(p) - Compaction delay (memory verbose mode only)
+ wpcopy(w) - Write page copy delay (memory verbose mode only)
+
+Advanced usage examples::
+
+ # ./delaytop -s blkio
+ Sorted by IO delay
+
+ # ./delaytop -s mem -M
+ Sorted by memory delay in memory verbose mode
# ./delaytop -p pid
Print delayacct stats
--
2.25.1
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