[to-be-updated] delaytop-sort-by-max-delay-to-highlight-top-latency-processes.patch removed from -mm tree
Andrew Morton <[email protected]> Mon, 03 Aug 2026 20:12:39 -0700
| Newsgroups | org.kernel.vger.mm-commits |
|---|---|
| Message-ID | <[email protected]> |
The quilt patch titled
Subject: delaytop: sort by max delay to highlight top latency processes
has been removed from the -mm tree. Its filename was
delaytop-sort-by-max-delay-to-highlight-top-latency-processes.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Wang Yaxin <[email protected]>
Subject: delaytop: sort by max delay to highlight top latency processes
Date: Thu, 2 Jul 2026 21:00:00 +0800 (CST)
When using -t/--type option, sort tasks by the maximum delay value of the
selected type in descending order (largest delay first).
This enables quickly identifying the top N processes with the highest
delay spikes, which is essential for diagnosing latency problems by
pinpointing which processes contributed most to system delays.
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Wang Yaxin <[email protected]>
Cc: Fan Yu <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: xu xin <[email protected]>
Cc: Yang Yang <[email protected]>
Cc: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
Documentation/accounting/delay-accounting.rst | 43 +++++++++
tools/accounting/delaytop.c | 71 +++++++++++++---
tools/accounting/getdelays.c | 5 +
3 files changed, 108 insertions(+), 11 deletions(-)
--- a/Documentation/accounting/delay-accounting.rst~delaytop-sort-by-max-delay-to-highlight-top-latency-processes
+++ a/Documentation/accounting/delay-accounting.rst
@@ -212,3 +212,46 @@ Advanced usage examples::
# ./delaytop -d secs
Specify refresh interval as secs
+
+ # ./delaytop -t type
+ Display only specified delay type with avg/max/timestamp
+ (rows sorted by MAX for that type, largest first)
+
+
+
+delaytop add delay_max fields to track the maximum delay value for each delay type
+(cpu, blkio, irq, swapin, freepages, thrashing, compact, wpcopy) per task.
+
+ bash# ./delaytop -t cpu
+ System Pressure Information: (avg10/avg60/avg300/total)
+ CPU some: 0.4%/ 0.2%/ 0.1%/ 220(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%/ 12(ms)
+ IO some: 0.0%/ 0.0%/ 0.0%/ 13(ms)
+ IRQ full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
+ [q]quit
+ Top 20 processes (sorted by cpu MAX delay, largest first):
+ PID TGID COMMAND AVG(ms) MAX(ms) MAX_TIMESTAMP
+ ------------------------------------------------------------------------
+ 9 9 kworker/0:0-eve 0.59 16.87 2026-05-27T13:32:39
+ 30 30 kworker/2:0H-kb 2.87 11.36 2026-05-27T13:32:36
+ 27 27 migration/2 1.05 9.51 2026-05-27T13:32:37
+ 50 50 kworker/2:1-eve 0.50 9.13 2026-05-27T13:32:37
+ 15 15 rcu_preempt 0.11 8.98 2026-05-27T13:32:37
+ 1 1 init 0.17 7.12 2026-05-27T13:32:38
+ 67 67 scsi_eh_0 1.20 4.23 2026-05-27T13:32:37
+ 23 23 ksoftirqd/1 1.12 3.77 2026-05-27T13:32:36
+ 3 3 pool_workqueue_ 0.72 3.55 2026-05-27T13:32:38
+ 62 62 kworker/u20:2-a 0.49 3.03 2026-05-27T13:32:37
+ 2 2 kthreadd 0.18 2.82 2026-05-27T13:32:37
+ 11 11 kworker/0:1 1.42 2.76 2026-05-27T13:32:36
+ 39 39 kworker/u20:0-a 0.10 2.71 2026-05-27T13:32:38
+ 17 17 rcu_exp_gp_kthr 0.25 2.65 2026-05-27T13:32:37
+ 66 66 kworker/u20:3-e 0.38 2.55 2026-05-27T13:32:37
+ 20 20 cpuhp/0 0.53 2.51 2026-05-27T13:32:37
+ 28 28 ksoftirqd/2 0.59 2.48 2026-05-27T13:32:37
+ 55 55 kworker/u19:1 0.88 2.42 2026-05-27T13:32:37
+ 13 13 kworker/R-mm_pe 1.18 2.35 2026-05-27T13:32:36
+ 54 54 kworker/3:1-eve 0.14 2.20 2026-05-27T13:32:38
--- a/tools/accounting/delaytop.c~delaytop-sort-by-max-delay-to-highlight-top-latency-processes
+++ a/tools/accounting/delaytop.c
@@ -295,6 +295,7 @@ static void usage(void)
" -C, --container=PATH Monitor the container at specified cgroup path\n"
" -s, --sort=FIELD Sort by delay field (default: cpu)\n"
" -t, --type=FIELD Display only specified delay type with avg/max/timestamp\n"
+ " (rows sorted by MAX for that type, largest first)\n"
" -M, --memverbose Display memory detailed information\n");
exit(0);
}
@@ -838,6 +839,15 @@ static void get_task_delays(void)
closedir(dir);
}
+static void field_delay_max_and_ts(const struct task_info *task,
+ const struct field_desc *field,
+ unsigned long long *max_ns,
+ struct __kernel_timespec *max_ts);
+static void get_field_delay_values(const struct task_info *task,
+ const struct field_desc *field,
+ double *avg_ms, double *max_ms,
+ struct __kernel_timespec *max_ts);
+
/* Calculate average delay in milliseconds */
static double average_ms(unsigned long long total, unsigned long long count)
{
@@ -850,7 +860,7 @@ static double average_ms(unsigned long l
* Format __kernel_timespec to human readable string (YYYY-MM-DDTHH:MM:SS)
* Returns formatted string or "N/A" if timestamp is zero
*/
-static const char *format_timespec64(struct __kernel_timespec *ts)
+static const char *format_kernel_timespec(struct __kernel_timespec *ts)
{
static char buffer[32];
time_t time_sec;
@@ -891,6 +901,16 @@ static int compare_tasks(const void *a,
unsigned long long count1;
unsigned long long count2;
double avg1, avg2;
+ unsigned long long max1, max2;
+
+ /* -t/--type: default sort by MAX column for the selected type (descending) */
+ if (cfg.display_mode == MODE_TYPE && cfg.type_field) {
+ field_delay_max_and_ts(t1, cfg.type_field, &max1, NULL);
+ field_delay_max_and_ts(t2, cfg.type_field, &max2, NULL);
+ if (max1 != max2)
+ return max2 > max1 ? 1 : -1;
+ return 0;
+ }
total1 = *(unsigned long long *)((char *)t1 + cfg.sort_field->total_offset);
total2 = *(unsigned long long *)((char *)t2 + cfg.sort_field->total_offset);
@@ -905,6 +925,28 @@ static int compare_tasks(const void *a,
return 0;
}
+/* Max delay (ns) and timestamp for field (shared by display and sort) */
+static void field_delay_max_and_ts(const struct task_info *task, const struct field_desc *field,
+ unsigned long long *max_ns, struct __kernel_timespec *max_ts)
+{
+ if (!field || !field->max_offset) {
+ *max_ns = 0;
+ if (max_ts)
+ memset(max_ts, 0, sizeof(*max_ts));
+ return;
+ }
+
+ *max_ns = *(unsigned long long *)((char *)task + field->max_offset);
+
+ if (max_ts) {
+ if (field->max_ts_offset)
+ *max_ts = *(struct __kernel_timespec *)((char *)task +
+ field->max_ts_offset);
+ else
+ memset(max_ts, 0, sizeof(*max_ts));
+ }
+}
+
/* Get delay values for a specific field */
static void get_field_delay_values(const struct task_info *task, const struct field_desc *field,
double *avg_ms, double *max_ms,
@@ -923,13 +965,8 @@ static void get_field_delay_values(const
count = *(unsigned long long *)((char *)task + field->count_offset);
*avg_ms = average_ms(total, count);
- max = *(unsigned long long *)((char *)task + field->max_offset);
+ field_delay_max_and_ts(task, field, &max, max_ts);
*max_ms = (double)max / 1000000.0; /* Convert nanoseconds to milliseconds */
-
- if (field->max_ts_offset)
- *max_ts = *(struct __kernel_timespec *)((char *)task + field->max_ts_offset);
- else
- memset(max_ts, 0, sizeof(*max_ts));
}
/* Sort tasks by selected field */
@@ -1079,7 +1116,10 @@ static void display_results(int psi_ret)
}
/* Interacive command */
- suc &= BOOL_FPRINT(out, "[o]sort [M]memverbose [q]quit\n");
+ if (cfg.display_mode == MODE_TYPE && cfg.type_field)
+ suc &= BOOL_FPRINT(out, "[q]quit\n");
+ else
+ suc &= BOOL_FPRINT(out, "[o]sort [M]memverbose [q]quit\n");
if (sort_selected) {
if (cfg.display_mode == MODE_MEMVERBOSE)
suc &= BOOL_FPRINT(out,
@@ -1090,8 +1130,13 @@ static void display_results(int psi_ret)
}
/* Task delay output */
- suc &= BOOL_FPRINT(out, "Top %d processes (sorted by %s delay):\n",
- cfg.max_processes, get_name_by_field(cfg.sort_field));
+ if (cfg.display_mode == MODE_TYPE && cfg.type_field)
+ suc &= BOOL_FPRINT(out,
+ "Top %d processes (sorted by %s MAX delay, largest first):\n",
+ cfg.max_processes, get_name_by_field(cfg.type_field));
+ else
+ suc &= BOOL_FPRINT(out, "Top %d processes (sorted by %s delay):\n",
+ cfg.max_processes, get_name_by_field(cfg.sort_field));
if (cfg.display_mode == MODE_TYPE && cfg.type_field) {
/* Display mode for -t option: show only specified type with avg/max/timestamp */
@@ -1132,7 +1177,7 @@ static void display_results(int psi_ret)
&max_ms, &max_ts);
suc &= BOOL_FPRINT(out, "%12.2f %12.2f %20s\n",
- avg_ms, max_ms, format_timespec64(&max_ts));
+ avg_ms, max_ms, format_kernel_timespec(&max_ts));
} else if (cfg.display_mode == MODE_MEMVERBOSE) {
suc &= BOOL_FPRINT(out, DELAY_FMT_MEMVERBOSE,
TASK_AVG(tasks[i], mem),
@@ -1201,9 +1246,13 @@ static void handle_keypress(char ch, int
} else {
switch (ch) {
case 'o':
+ if (cfg.display_mode == MODE_TYPE)
+ break;
sort_selected = 1;
break;
case 'M':
+ if (cfg.display_mode == MODE_TYPE)
+ break;
toggle_display_mode();
for (field = sort_fields; field->name != NULL; field++) {
if (field->supported_modes & cfg.display_mode) {
--- a/tools/accounting/getdelays.c~delaytop-sort-by-max-delay-to-highlight-top-latency-processes
+++ a/tools/accounting/getdelays.c
@@ -235,6 +235,11 @@ static const char *format_timespec(struc
if (ts->tv_sec == 0 && ts->tv_nsec == 0)
return "N/A";
+ /* Avoid Y2038 truncation on 32-bit platforms */
+ if (sizeof(time_sec) < sizeof(ts->tv_sec) &&
+ ts->tv_sec > (__u64)((1ULL << (sizeof(time_sec) * 8 - 1)) - 1))
+ return "N/A";
+
time_sec = ts->tv_sec;
/* Use thread-safe localtime_r */
_
Patches currently in -mm which might be from [email protected] are