[to-be-updated] delaytop-add-delay-max-for-delaytop.patch removed from -mm tree
Andrew Morton <[email protected]> Mon, 03 Aug 2026 20:12:37 -0700
| Newsgroups | org.kernel.vger.mm-commits |
|---|---|
| Message-ID | <[email protected]> |
The quilt patch titled
Subject: delaytop: add delay max for delaytop
has been removed from the -mm tree. Its filename was
delaytop-add-delay-max-for-delaytop.patch
This patch was dropped because an updated version will be issued
------------------------------------------------------
From: Wang Yaxin <[email protected]>
Subject: delaytop: add delay max for delaytop
Date: Thu, 2 Jul 2026 20:58:15 +0800 (CST)
Patch series "delaytop: add delay max, timestamp and sorting for top
latency analysis".
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.
This patch (of 3):
Previously delaytop only showed average delays. Add delay_max fields to
track the maximum delay value for each delay type (cpu, blkio, irq,
swapin, freepages, thrashing, compact, wpcopy) per task.
This provides a global view of all tasks' delay spikes, which is essential
for identifying processes that experienced brief but significant latency
events that would be hidden by average-only metrics.
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
Link: https://lore.kernel.org/[email protected]
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]>
Signed-off-by: Andrew Morton <[email protected]>
---
tools/accounting/delaytop.c | 165 ++++++++++++++++++++++++++--------
1 file changed, 131 insertions(+), 34 deletions(-)
--- a/tools/accounting/delaytop.c~delaytop-add-delay-max-for-delaytop
+++ a/tools/accounting/delaytop.c
@@ -75,13 +75,21 @@
{#name, #cmd, \
offsetof(struct task_info, name##_delay_total), \
offsetof(struct task_info, name##_count), \
+ offsetof(struct task_info, name##_delay_max), \
modes}
-#define END_FIELD {NULL, 0, 0}
+#define SORT_FIELD_NO_MAX(name, cmd, modes) \
+ {#name, #cmd, \
+ offsetof(struct task_info, name##_delay_total), \
+ offsetof(struct task_info, name##_count), \
+ 0, \
+ modes}
+#define END_FIELD {NULL, 0, 0, 0, 0, 0}
/* Display mode types */
#define MODE_TYPE_ALL (0xFFFFFFFF)
#define MODE_DEFAULT (1 << 0)
#define MODE_MEMVERBOSE (1 << 1)
+#define MODE_TYPE (1 << 2) /* Display specific type with avg/max */
/* PSI statistics structure */
struct psi_stats {
@@ -108,20 +116,28 @@ struct task_info {
char command[TASK_COMM_LEN];
unsigned long long cpu_count;
unsigned long long cpu_delay_total;
+ unsigned long long cpu_delay_max;
unsigned long long blkio_count;
unsigned long long blkio_delay_total;
+ unsigned long long blkio_delay_max;
unsigned long long swapin_count;
unsigned long long swapin_delay_total;
+ unsigned long long swapin_delay_max;
unsigned long long freepages_count;
unsigned long long freepages_delay_total;
+ unsigned long long freepages_delay_max;
unsigned long long thrashing_count;
unsigned long long thrashing_delay_total;
+ unsigned long long thrashing_delay_max;
unsigned long long compact_count;
unsigned long long compact_delay_total;
+ unsigned long long compact_delay_max;
unsigned long long wpcopy_count;
unsigned long long wpcopy_delay_total;
+ unsigned long long wpcopy_delay_max;
unsigned long long irq_count;
unsigned long long irq_delay_total;
+ unsigned long long irq_delay_max;
unsigned long long mem_count;
unsigned long long mem_delay_total;
};
@@ -141,6 +157,7 @@ struct field_desc {
const char *cmd_char; /* Interactive command */
unsigned long total_offset; /* Offset of total delay in task_info */
unsigned long count_offset; /* Offset of count in task_info */
+ unsigned long max_offset; /* Offset of max delay in task_info */
size_t supported_modes; /* Supported display modes */
};
@@ -153,6 +170,7 @@ struct config {
int monitor_pid; /* Monitor specific PID */
char *container_path; /* Path to container cgroup */
const struct field_desc *sort_field; /* Current sort field */
+ const struct field_desc *type_field; /* Type field for -t option */
size_t display_mode; /* Current display mode */
};
@@ -164,15 +182,15 @@ static int task_count;
static int running = 1;
static struct container_stats container_stats;
static const struct field_desc sort_fields[] = {
- SORT_FIELD(cpu, c, MODE_DEFAULT),
- SORT_FIELD(blkio, i, MODE_DEFAULT),
- SORT_FIELD(irq, q, MODE_DEFAULT),
- SORT_FIELD(mem, m, MODE_DEFAULT | MODE_MEMVERBOSE),
- SORT_FIELD(swapin, s, MODE_MEMVERBOSE),
- SORT_FIELD(freepages, r, MODE_MEMVERBOSE),
- SORT_FIELD(thrashing, t, MODE_MEMVERBOSE),
- SORT_FIELD(compact, p, MODE_MEMVERBOSE),
- SORT_FIELD(wpcopy, w, MODE_MEMVERBOSE),
+ SORT_FIELD(cpu, c, MODE_DEFAULT | MODE_TYPE),
+ SORT_FIELD(blkio, i, MODE_DEFAULT | MODE_TYPE),
+ SORT_FIELD(irq, q, MODE_DEFAULT | MODE_TYPE),
+ SORT_FIELD_NO_MAX(mem, m, MODE_DEFAULT | MODE_MEMVERBOSE),
+ SORT_FIELD(swapin, s, MODE_MEMVERBOSE | MODE_TYPE),
+ SORT_FIELD(freepages, r, MODE_MEMVERBOSE | MODE_TYPE),
+ SORT_FIELD(thrashing, t, MODE_MEMVERBOSE | MODE_TYPE),
+ SORT_FIELD(compact, p, MODE_MEMVERBOSE | MODE_TYPE),
+ SORT_FIELD(wpcopy, w, MODE_MEMVERBOSE | MODE_TYPE),
END_FIELD
};
static int sort_selected;
@@ -265,6 +283,7 @@ static void usage(void)
" -p, --pid=PID Monitor only the specified PID\n"
" -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\n"
" -M, --memverbose Display memory detailed information\n");
exit(0);
}
@@ -283,6 +302,7 @@ static void parse_args(int argc, char **
{"processes", required_argument, 0, 'P'},
{"sort", required_argument, 0, 's'},
{"container", required_argument, 0, 'C'},
+ {"type", required_argument, 0, 't'},
{"memverbose", no_argument, 0, 'M'},
{0, 0, 0, 0}
};
@@ -292,6 +312,7 @@ static void parse_args(int argc, char **
cfg.iterations = 0;
cfg.max_processes = 20;
cfg.sort_field = &sort_fields[0]; /* Default sorted by CPU delay */
+ cfg.type_field = NULL; /* No type field by default */
cfg.output_one_time = 0;
cfg.monitor_pid = 0; /* 0 means monitor all PIDs */
cfg.container_path = NULL;
@@ -300,7 +321,7 @@ static void parse_args(int argc, char **
while (1) {
int option_index = 0;
- c = getopt_long(argc, argv, "hd:n:p:oP:C:s:M", long_options, &option_index);
+ c = getopt_long(argc, argv, "hd:n:p:oP:C:s:t:M", long_options, &option_index);
if (c == -1)
break;
@@ -363,9 +384,32 @@ static void parse_args(int argc, char **
cfg.sort_field = field;
break;
+ case 't':
+ if (strlen(optarg) == 0) {
+ fprintf(stderr, "Error: empty type field\n");
+ exit(1);
+ }
+
+ field = get_field_by_name(optarg);
+ /* Show available fields if invalid option provided */
+ if (!field || !(field->supported_modes & MODE_TYPE)) {
+ fprintf(stderr, "Error: invalid type field '%s'\n", optarg);
+ display_available_fields(MODE_TYPE);
+ exit(1);
+ }
+
+ cfg.type_field = field;
+ cfg.display_mode = MODE_TYPE;
+ break;
case 'M':
cfg.display_mode = MODE_MEMVERBOSE;
- cfg.sort_field = get_field_by_name("mem");
+ /* Find first field supporting MODE_MEMVERBOSE for sorting */
+ for (field = sort_fields; field->name != NULL; field++) {
+ if (field->supported_modes & MODE_MEMVERBOSE) {
+ cfg.sort_field = field;
+ break;
+ }
+ }
break;
default:
fprintf(stderr, "Try 'delaytop --help' for more information.\n");
@@ -690,7 +734,12 @@ static void fetch_and_fill_task_info(int
nested_len = NLA_PAYLOAD(na->nla_len);
while (nested_len > 0) {
if (nested->nla_type == TASKSTATS_TYPE_STATS) {
- memcpy(&stats, NLA_DATA(nested), sizeof(stats));
+ size_t payload_len = NLA_PAYLOAD(nested->nla_len);
+
+ memset(&stats, 0, sizeof(stats));
+ if (payload_len > sizeof(stats))
+ payload_len = sizeof(stats);
+ memcpy(&stats, NLA_DATA(nested), payload_len);
if (task_count < MAX_TASKS) {
tasks[task_count].pid = pid;
tasks[task_count].tgid = pid;
@@ -699,20 +748,28 @@ static void fetch_and_fill_task_info(int
tasks[task_count].command[TASK_COMM_LEN - 1] = '\0';
SET_TASK_STAT(task_count, cpu_count);
SET_TASK_STAT(task_count, cpu_delay_total);
+ SET_TASK_STAT(task_count, cpu_delay_max);
SET_TASK_STAT(task_count, blkio_count);
SET_TASK_STAT(task_count, blkio_delay_total);
+ SET_TASK_STAT(task_count, blkio_delay_max);
SET_TASK_STAT(task_count, swapin_count);
SET_TASK_STAT(task_count, swapin_delay_total);
+ SET_TASK_STAT(task_count, swapin_delay_max);
SET_TASK_STAT(task_count, freepages_count);
SET_TASK_STAT(task_count, freepages_delay_total);
+ SET_TASK_STAT(task_count, freepages_delay_max);
SET_TASK_STAT(task_count, thrashing_count);
SET_TASK_STAT(task_count, thrashing_delay_total);
+ SET_TASK_STAT(task_count, thrashing_delay_max);
SET_TASK_STAT(task_count, compact_count);
SET_TASK_STAT(task_count, compact_delay_total);
+ SET_TASK_STAT(task_count, compact_delay_max);
SET_TASK_STAT(task_count, wpcopy_count);
SET_TASK_STAT(task_count, wpcopy_delay_total);
+ SET_TASK_STAT(task_count, wpcopy_delay_max);
SET_TASK_STAT(task_count, irq_count);
SET_TASK_STAT(task_count, irq_delay_total);
+ SET_TASK_STAT(task_count, irq_delay_max);
set_mem_count(&tasks[task_count]);
set_mem_delay_total(&tasks[task_count]);
task_count++;
@@ -777,14 +834,14 @@ static int compare_tasks(const void *a,
const struct task_info *t2 = (const struct task_info *)b;
unsigned long long total1;
unsigned long long total2;
- unsigned long count1;
- unsigned long count2;
+ unsigned long long count1;
+ unsigned long long count2;
double avg1, avg2;
total1 = *(unsigned long long *)((char *)t1 + cfg.sort_field->total_offset);
total2 = *(unsigned long long *)((char *)t2 + cfg.sort_field->total_offset);
- count1 = *(unsigned long *)((char *)t1 + cfg.sort_field->count_offset);
- count2 = *(unsigned long *)((char *)t2 + cfg.sort_field->count_offset);
+ count1 = *(unsigned long long *)((char *)t1 + cfg.sort_field->count_offset);
+ count2 = *(unsigned long long *)((char *)t2 + cfg.sort_field->count_offset);
avg1 = average_ms(total1, count1);
avg2 = average_ms(total2, count2);
@@ -794,6 +851,26 @@ static int compare_tasks(const void *a,
return 0;
}
+/* 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)
+{
+ unsigned long long total, count, max;
+
+ if (!field || !field->max_offset) {
+ *avg_ms = 0;
+ *max_ms = 0;
+ return;
+ }
+
+ total = *(unsigned long long *)((char *)task + field->total_offset);
+ count = *(unsigned long long *)((char *)task + field->count_offset);
+ *avg_ms = average_ms(total, count);
+
+ max = *(unsigned long long *)((char *)task + field->max_offset);
+ *max_ms = (double)max / 1000000.0; /* Convert nanoseconds to milliseconds */
+}
+
/* Sort tasks by selected field */
static void sort_tasks(void)
{
@@ -847,7 +924,12 @@ static void get_container_stats(void)
while (nl_len > 0) {
if (na->nla_type == CGROUPSTATS_TYPE_CGROUP_STATS) {
/* Get the cgroupstats structure */
- memcpy(&stats, NLA_DATA(na), sizeof(stats));
+ size_t payload_len = NLA_PAYLOAD(na->nla_len);
+
+ memset(&stats, 0, sizeof(stats));
+ if (payload_len > sizeof(stats))
+ payload_len = sizeof(stats);
+ memcpy(&stats, NLA_DATA(na), payload_len);
/* Fill container stats */
container_stats.nr_sleeping = stats.nr_sleeping;
@@ -950,29 +1032,44 @@ static void display_results(int psi_ret)
suc &= BOOL_FPRINT(out, "Top %d processes (sorted by %s delay):\n",
cfg.max_processes, get_name_by_field(cfg.sort_field));
- suc &= BOOL_FPRINT(out, "%8s %8s %-17s", "PID", "TGID", "COMMAND");
- if (cfg.display_mode == MODE_MEMVERBOSE) {
- suc &= BOOL_FPRINT(out, "%8s %8s %8s %8s %8s %8s\n",
- "MEM(ms)", "SWAP(ms)", "RCL(ms)",
- "THR(ms)", "CMP(ms)", "WP(ms)");
- suc &= BOOL_FPRINT(out, "-----------------------");
- suc &= BOOL_FPRINT(out, "-----------------------");
- suc &= BOOL_FPRINT(out, "-----------------------");
- suc &= BOOL_FPRINT(out, "---------------------\n");
+ if (cfg.display_mode == MODE_TYPE && cfg.type_field) {
+ /* Display mode for -t option: show only specified type with avg/max */
+ suc &= BOOL_FPRINT(out, "%8s %8s %-17s %12s %12s\n",
+ "PID", "TGID", "COMMAND",
+ "AVG(ms)", "MAX(ms)");
+ suc &= BOOL_FPRINT(out, "----------------------------------------------------\n");
} else {
- suc &= BOOL_FPRINT(out, "%8s %8s %8s %8s\n",
- "CPU(ms)", "IO(ms)", "IRQ(ms)", "MEM(ms)");
- suc &= BOOL_FPRINT(out, "-----------------------");
- suc &= BOOL_FPRINT(out, "-----------------------");
- suc &= BOOL_FPRINT(out, "--------------------------\n");
+ suc &= BOOL_FPRINT(out, "%8s %8s %-17s", "PID", "TGID", "COMMAND");
+ if (cfg.display_mode == MODE_MEMVERBOSE) {
+ suc &= BOOL_FPRINT(out, "%8s %8s %8s %8s %8s %8s\n",
+ "MEM(ms)", "SWAP(ms)", "RCL(ms)",
+ "THR(ms)", "CMP(ms)", "WP(ms)");
+ suc &= BOOL_FPRINT(out, "-----------------------");
+ suc &= BOOL_FPRINT(out, "-----------------------");
+ suc &= BOOL_FPRINT(out, "-----------------------");
+ suc &= BOOL_FPRINT(out, "---------------------\n");
+ } else {
+ suc &= BOOL_FPRINT(out, "%8s %8s %8s %8s\n",
+ "CPU(ms)", "IO(ms)", "IRQ(ms)", "MEM(ms)");
+ suc &= BOOL_FPRINT(out, "-----------------------");
+ suc &= BOOL_FPRINT(out, "-----------------------");
+ suc &= BOOL_FPRINT(out, "--------------------------\n");
+ }
}
count = task_count < cfg.max_processes ? task_count : cfg.max_processes;
for (i = 0; i < count; i++) {
- suc &= BOOL_FPRINT(out, "%8d %8d %-15s",
+ suc &= BOOL_FPRINT(out, "%8d %8d %-17s",
tasks[i].pid, tasks[i].tgid, tasks[i].command);
- if (cfg.display_mode == MODE_MEMVERBOSE) {
+ if (cfg.display_mode == MODE_TYPE && cfg.type_field) {
+ double avg_ms, max_ms;
+
+ get_field_delay_values(&tasks[i], cfg.type_field, &avg_ms, &max_ms);
+
+ suc &= BOOL_FPRINT(out, "%12.2f %12.2f\n",
+ avg_ms, max_ms);
+ } else if (cfg.display_mode == MODE_MEMVERBOSE) {
suc &= BOOL_FPRINT(out, DELAY_FMT_MEMVERBOSE,
TASK_AVG(tasks[i], mem),
TASK_AVG(tasks[i], swapin),
_
Patches currently in -mm which might be from [email protected] are
delaytop-add-timestamp-of-delay-max.patch
delaytop-sort-by-max-delay-to-highlight-top-latency-processes.patch