From: Wang Yaxin <wang.yaxin@zte.com.cn>
Previously delaytop only showed average delays. This patch adds:
1. delay_max fields to track the maximum delay value for each delay type
(cpu, blkio, irq, swapin, freepages, thrashing, compact, wpcopy)
per task.
2. The -t/--type option displays only the specified delay type with avg/max
values side by side, allowing focused analysis:
delaytop -t cpu # Show only CPU delay with avg/max
delaytop -t wpcopy # Show Copy-on-Write delay with avg/max
3. Wall-clock timestamp when each maximum delay occurred, displayed in the
MAX_TIMESTAMP column when using -t/--type option. This enables:
- Identifying the time when a process experienced an abnormal delay max
- Correlating delay max across multiple processes at the same timestamp
- Cross-referencing with logs, traces, or other metrics at that time
4. When using -t/--type option, tasks are sorted by maximum delay value in
descending order (largest delay first), enabling quick identification of
top N processes with highest delay spikes.
Signed-off-by: Wang Yaxin <wang.yaxin@zte.com.cn>
v3->v4:
[patch 3/3]
1. Fix ReST syntax errors (indentation, list formatting) that triggered
warnings when running 'make htmldocs'. No content changes are made.
v2->v3:
[patch 1/3]
1. fix get_field_by_name() MODE_TYPE filter breaking --sort for non-type fields
2. zero-init stats struct and cap memcpy size in netlink response parsing
3. fix compare_tasks() count field read as unsigned long long for 32-bit safety
[patch 2/3]
1. fix 32-bit time_t overflow check to use max representable value instead of (time_t)-1
2. fix gmtime() pointer aliasing by assigning timespec64 tv_sec to local time_t
[patch 3/3]
1. fixed Y2038 overflow false negative in format_kernel_timespec()
2. switched to localtime_r() with stack `struct tm` for thread safety.
Wang Yaxin (3):
delaytop: add delay max for delaytop
delaytop: add timestamp of delay max
delaytop: sort by max delay to highlight top latency processes
Documentation/accounting/delay-accounting.rst | 87 ++++--
Documentation/sphinx/maintainers_include.py | 2 +-
tools/accounting/delaytop.c | 286 +++++++++++++++---
tools/accounting/getdelays.c | 5 +
4 files changed, 319 insertions(+), 61 deletions(-)
--
2.47.1