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
..
accounting	delayacct: add timestamp of delay max	2026-01-31 16:16:06 -08:00
arch	tools headers: Sync arm64 headers with kernel sources	2025-12-24 11:43:12 -08:00
bootconfig
bpf	bpftool: Fix build warnings due to MS extensions	2025-12-09 23:21:33 -08:00
build	tools build: Fix the common set of features test wrt libopenssl	2025-12-27 20:26:44 -08:00
certs
cgroup
counter
crypto
debugging	kernel-chktaint: add reporting for tainted modules	2026-01-26 19:07:15 -08:00
dma	dma-mapping updates for Linux 6.19:	2025-12-06 09:25:05 -08:00
docs	docs: makefile: move rustdoc check to the build wrapper	2025-11-29 08:42:53 -07:00
firewire
firmware
gpio
hv
iio	iio: add power and energy measurement modifiers	2025-09-13 13:47:19 +01:00
include	treewide: Update email address	2026-01-11 06:09:11 -10:00
kvm/kvm_stat
laptop
leds
lib	bpf-fixes	2025-12-17 15:54:58 +12:00
memory-model
mm	tools/mm/page_owner_sort: fix timestamp comparison for stable sorting	2025-12-23 11:23:14 -08:00
net	tools: ynl: render event op docs correctly	2026-01-13 11:56:36 -08:00
objtool	objtool: fix build failure due to missing libopcodes check	2026-01-13 11:37:51 +01:00
pcmcia
perf	treewide: Update email address	2026-01-11 06:09:11 -10:00
power	platform-drivers-x86 for v6.19-1	2025-12-10 06:38:17 +09:00
rcu
sched
sched_ext	tools/sched_ext: update scx_show_state.py for scx_aborting change	2025-12-28 06:11:26 -10:00
scripts	tools headers: Sync syscall table with kernel sources	2025-12-24 11:43:36 -08:00
sound
spi
testing	watchdog: softlockup: panic when lockup duration exceeds N thresholds	2026-01-20 19:44:20 -08:00
thermal	tools/thermal/thermal-engine: Fix format string bug in thermal-engine	2025-11-25 11:00:28 +01:00
time
tracing	rtla updaets for v6.19:	2025-12-05 09:34:01 -08:00
usb
verification
virtio	tools/virtio: add device, device_driver stubs	2025-12-24 08:02:56 -05:00
wmi
workqueue
writeback
Makefile	tools/dma: move dma_map_benchmark from selftests to tools/dma	2025-10-29 09:41:40 +01:00