docs: update delaytop documentation for new interactive features

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

Link: https://lkml.kernel.org/r/20250907001457696qAqUGGkV1VfEO6OkVMovW@zte.com.cn
Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
Reviewed-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst
index 8ccc5af5ea1eedc2ce6bc9c560948198ca36c434..86d7902a657f3eacb06f88bd4765b2b66e809638 100644 (file)
--- 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