Wang Yaxin 503efe850c delayacct: add timestamp of delay max ... Problem ======= Commit 658eb5ab91 ("delayacct: add delay max to record delay peak") introduced the delay max for getdelays, which records abnormal latency peaks and helps us understand the magnitude of such delays. However, the peak latency value alone is insufficient for effective root cause analysis. Without the precise timestamp of when the peak occurred, we still lack the critical context needed to correlate it with other system events. Solution ======== To address this, we need to additionally record a precise timestamp when the maximum latency occurs. By correlating this timestamp with system logs and monitoring metrics, we can identify processes with abnormal resource usage at the same moment, which can help us to pinpoint root causes. Use Case ======== bash-4.4# ./getdelays -d -t 227 print delayacct stats ON TGID 227 CPU count real total virtual total delay total delay average delay max delay min delay max timestamp 46 188000000 192348334 4098012 0.089ms 0.429260ms 0.051205ms 2026-01-15T15:06:58 IO count delay total delay average delay max delay min delay max timestamp 0 0 0.000ms 0.000000ms 0.000000ms N/A SWAP count delay total delay average delay max delay min delay max timestamp 0 0 0.000ms 0.000000ms 0.000000ms N/A RECLAIM count delay total delay average delay max delay min delay max timestamp 0 0 0.000ms 0.000000ms 0.000000ms N/A THRAS HING count delay total delay average delay max delay min delay max timestamp 0 0 0.000ms 0.000000ms 0.000000ms N/A COMPACT count delay total delay average delay max delay min delay max timestamp 0 0 0.000ms 0.000000ms 0.000000ms N/A WPCOPY count delay total delay average delay max delay min delay max timestamp 182 19413338 0.107ms 0.547353ms 0.022462ms 2026-01-15T15:05:24 IRQ count delay total delay average delay max delay min delay max timestamp 0 0 0.000ms 0.000000ms 0.000000ms N/A Link: https://lkml.kernel.org/r/20260119100241520gWubW8-5QfhSf9gjqcc_E@zte.com.cn Signed-off-by: Wang Yaxin <wang.yaxin@zte.com.cn> Cc: Fan Yu <fan.yu9@zte.com.cn> Cc: Jonathan Corbet <corbet@lwn.net> Cc: xu xin <xu.xin16@zte.com.cn> Cc: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>		2026-01-31 16:16:06 -08:00
..
cgroupstats.rst	Documentation: Replace lkml.org links with lore	2021-01-11 12:47:38 -07:00
delay-accounting.rst	delayacct: add timestamp of delay max	2026-01-31 16:16:06 -08:00
index.rst	docs: add some documentation dirs to the driver-api book	2019-07-15 11:03:02 -03:00
psi.rst	docs: psi: use correct config name	2023-07-31 09:54:17 -06:00
taskstats-struct.rst	Documentation/accounting: Fix typo in taskstats-struct.rst	2024-12-13 08:44:29 -07:00
taskstats.rst	Documentation: taskstats: Reindent payload kinds list	2025-11-10 12:52:12 -07:00