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Message-ID: <202507281628341752gMXCMN7S-Vz_LHYHum9r@zte.com.cn>
Date: Mon, 28 Jul 2025 16:28:34 +0800 (CST)
From: <fan.yu9@....com.cn>
To: <akpm@...ux-foundation.org>, <wang.yaxin@....com.cn>, <corbet@....net>,
<yang.yang29@....com.cn>
Cc: <linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<fan.yu9@....com.cn>, <xu.xin16@....com.cn>
Subject: [PATCH linux-next] delaytop: Enhance error logging and add PSI feature description
This patch improves error diagnostics and documentation for delaytop:
1) Enhanced error logging:
- Added explicit error messages in critical failure paths
- Implemented BOOL_FPRINT macro for robust output handling
2) PSI feature documentation:
- Updated header comment to reflect PSI monitoring capability
- Improved output formatting for PSI information
System Pressure Information: (avg10/avg60/avg300/total)
CPU some: 0.0%/ 0.0%/ 0.0%/ 345(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%/ 65(ms)
IO some: 0.0%/ 0.0%/ 0.0%/ 79(ms)
IRQ full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
Signed-off-by: Fan Yu <fan.yu9@....com.cn>
Signed-off-by: Wang Yaxin <wang.yaxin@....com.cn>
---
Documentation/accounting/delay-accounting.rst | 61 ++++---
tools/accounting/delaytop.c | 162 ++++++++++++------
2 files changed, 143 insertions(+), 80 deletions(-)
diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst
index 664950328fb7..8ccc5af5ea1e 100644
--- a/Documentation/accounting/delay-accounting.rst
+++ b/Documentation/accounting/delay-accounting.rst
@@ -132,38 +132,47 @@ Get IO accounting for pid 1, it works only with -p::
The above command can be used with -v to get more debug information.
-After the system starts, use `delaytop` to get the Top-N high-latency tasks.
-this tool supports sorting by CPU latency in descending order by default,
+After the system starts, use `delaytop` to get the system-wide delay information,
+which includes system-wide PSI information and Top-N high-latency tasks.
+
+`delaytop` supports sorting by CPU latency in descending order by default,
displays the top 20 high-latency tasks by default, and refreshes the latency
data every 2 seconds by default.
-Get Top-N tasks delay, since system boot::
+Get PSI information and Top-N tasks delay, since system boot::
bash# ./delaytop
+ System Pressure Information: (avg10/avg60/avg300/total)
+ CPU some: 0.0%/ 0.0%/ 0.0%/ 345(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%/ 65(ms)
+ IO some: 0.0%/ 0.0%/ 0.0%/ 79(ms)
+ IRQ full: 0.0%/ 0.0%/ 0.0%/ 0(ms)
Top 20 processes (sorted by CPU delay):
-
- PID TGID COMMAND CPU(ms) IO(ms) SWAP(ms) RCL(ms) THR(ms) CMP(ms) WP(ms) IRQ(ms)
- ---------------------------------------------------------------------------------------------
- 32 32 kworker/2:0H-sy 23.65 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 497 497 kworker/R-scsi_ 1.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 495 495 kworker/R-scsi_ 1.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 494 494 scsi_eh_0 1.12 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 485 485 kworker/R-ata_s 0.90 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 574 574 kworker/R-kdmfl 0.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 34 34 idle_inject/3 0.33 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1123 1123 nde-netfilter 0.28 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 60 60 ksoftirqd/7 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 114 114 kworker/0:2-cgr 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 496 496 scsi_eh_1 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 51 51 cpuhp/6 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1667 1667 atd 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 45 45 cpuhp/5 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1102 1102 nde-backupservi 0.22 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1098 1098 systemsettings 0.21 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1100 1100 audit-monitor 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 53 53 migration/6 0.20 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 1482 1482 sshd 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00
- 39 39 cpuhp/4 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ PID TGID COMMAND CPU(ms) IO(ms) SWAP(ms) RCL(ms) THR(ms) CMP(ms) WP(ms) IRQ(ms)
+ ----------------------------------------------------------------------------------------------
+ 161 161 zombie_memcg_re 1.40 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 130 130 blkcg_punt_bio 1.37 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 444 444 scsi_tmf_0 0.73 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 1280 1280 rsyslogd 0.53 0.04 0.00 0.00 0.00 0.00 0.00 0.00
+ 12 12 ksoftirqd/0 0.47 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 1277 1277 nbd-server 0.44 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 308 308 kworker/2:2-sys 0.41 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 55 55 netns 0.36 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 1187 1187 acpid 0.31 0.03 0.00 0.00 0.00 0.00 0.00 0.00
+ 6184 6184 kworker/1:2-sys 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 186 186 kaluad 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 18 18 ksoftirqd/1 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 185 185 kmpath_rdacd 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 190 190 kstrp 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 2759 2759 agetty 0.20 0.03 0.00 0.00 0.00 0.00 0.00 0.00
+ 1190 1190 kworker/0:3-sys 0.19 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 1272 1272 sshd 0.15 0.04 0.00 0.00 0.00 0.00 0.00 0.00
+ 1156 1156 license 0.15 0.11 0.00 0.00 0.00 0.00 0.00 0.00
+ 134 134 md 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00
+ 6142 6142 kworker/3:2-xfs 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Dynamic interactive interface of delaytop::
diff --git a/tools/accounting/delaytop.c b/tools/accounting/delaytop.c
index cd848af9a856..9afb1ffc00ba 100644
--- a/tools/accounting/delaytop.c
+++ b/tools/accounting/delaytop.c
@@ -1,16 +1,16 @@
// SPDX-License-Identifier: GPL-2.0
/*
- * delaytop.c - task delay monitoring tool.
+ * delaytop.c - system-wide delay monitoring tool.
*
* This tool provides real-time monitoring and statistics of
* system, container, and task-level delays, including CPU,
- * memory, IO, and IRQ and delay accounting. It supports both
- * interactive (top-like), and can output delay information
- * for the whole system, specific containers (cgroups), or
- * individual tasks (PIDs).
+ * memory, IO, and IRQ. It supports both interactive (top-like),
+ * and can output delay information for the whole system, specific
+ * containers (cgroups), or individual tasks (PIDs).
*
* Key features:
* - Collects per-task delay accounting statistics via taskstats.
+ * - Collects system-wide PSI information.
* - Supports sorting, filtering.
* - Supports both interactive (screen refresh).
*
@@ -32,6 +32,7 @@
#include <time.h>
#include <dirent.h>
#include <ctype.h>
+#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
@@ -41,7 +42,6 @@
#include <linux/genetlink.h>
#include <linux/taskstats.h>
#include <linux/cgroupstats.h>
-#include <ncurses.h>
#define PSI_CPU_SOME "/proc/pressure/cpu"
#define PSI_CPU_FULL "/proc/pressure/cpu"
@@ -62,6 +62,12 @@
#define MAX_MSG_SIZE 1024
#define MAX_TASKS 1000
#define SET_TASK_STAT(task_count, field) tasks[task_count].field = stats.field
+#define BOOL_FPRINT(stream, fmt, ...) \
+({ \
+ int ret = fprintf(stream, fmt, ##__VA_ARGS__); \
+ ret >= 0; \
+})
+#define PSI_LINE_FORMAT "%-12s %6.1f%%/%6.1f%%/%6.1f%%/%8llu(ms)\n"
/* Program settings structure */
struct config {
@@ -262,6 +268,7 @@ static int create_nl_socket(void)
local.nl_family = AF_NETLINK;
if (bind(fd, (struct sockaddr *) &local, sizeof(local)) < 0) {
+ fprintf(stderr, "Failed to bind socket when create nl_socket\n");
close(fd);
return -1;
}
@@ -332,13 +339,17 @@ static int get_family_id(int sd)
rc = send_cmd(sd, GENL_ID_CTRL, getpid(), CTRL_CMD_GETFAMILY,
CTRL_ATTR_FAMILY_NAME, (void *)name,
strlen(TASKSTATS_GENL_NAME)+1);
- if (rc < 0)
+ if (rc < 0) {
+ fprintf(stderr, "Failed to send cmd for family id\n");
return 0;
+ }
rep_len = recv(sd, &ans, sizeof(ans), 0);
if (ans.n.nlmsg_type == NLMSG_ERROR ||
- (rep_len < 0) || !NLMSG_OK((&ans.n), rep_len))
+ (rep_len < 0) || !NLMSG_OK((&ans.n), rep_len)) {
+ fprintf(stderr, "Failed to receive response for family id\n");
return 0;
+ }
na = (struct nlattr *) GENLMSG_DATA(&ans);
na = (struct nlattr *) ((char *) na + NLA_ALIGN(na->nla_len));
@@ -433,26 +444,30 @@ static void read_psi_stats(void)
static int read_comm(int pid, char *comm_buf, size_t buf_size)
{
char path[64];
+ int ret = -1;
size_t len;
FILE *fp;
snprintf(path, sizeof(path), "/proc/%d/comm", pid);
fp = fopen(path, "r");
- if (!fp)
- return -1;
+ if (!fp) {
+ fprintf(stderr, "Failed to open comm file /proc/%d/comm\n", pid);
+ return ret;
+ }
+
if (fgets(comm_buf, buf_size, fp)) {
len = strlen(comm_buf);
if (len > 0 && comm_buf[len - 1] == '\n')
comm_buf[len - 1] = '\0';
- } else {
- fclose(fp);
- return -1;
+ ret = 0;
}
+
fclose(fp);
- return 0;
+
+ return ret;
}
-static int fetch_and_fill_task_info(int pid, const char *comm)
+static void fetch_and_fill_task_info(int pid, const char *comm)
{
struct {
struct nlmsghdr n;
@@ -466,13 +481,21 @@ static int fetch_and_fill_task_info(int pid, const char *comm)
int nl_len;
int rc;
+ /* Send request for task stats */
if (send_cmd(nl_sd, family_id, getpid(), TASKSTATS_CMD_GET,
TASKSTATS_CMD_ATTR_PID, &pid, sizeof(pid)) < 0) {
- return -1;
+ fprintf(stderr, "Failed to send request for task stats\n");
+ return;
}
+
+ /* Receive response */
rc = recv(nl_sd, &resp, sizeof(resp), 0);
- if (rc < 0 || resp.n.nlmsg_type == NLMSG_ERROR)
- return -1;
+ if (rc < 0 || resp.n.nlmsg_type == NLMSG_ERROR) {
+ fprintf(stderr, "Failed to receive response for task stats\n");
+ return;
+ }
+
+ /* Parse response */
nl_len = GENLMSG_PAYLOAD(&resp.n);
na = (struct nlattr *) GENLMSG_DATA(&resp);
while (nl_len > 0) {
@@ -515,7 +538,7 @@ static int fetch_and_fill_task_info(int pid, const char *comm)
nl_len -= NLA_ALIGN(na->nla_len);
na = NLA_NEXT(na);
}
- return 0;
+ return;
}
static void get_task_delays(void)
@@ -654,54 +677,82 @@ static void display_results(void)
{
time_t now = time(NULL);
struct tm *tm_now = localtime(&now);
+ FILE *out = stdout;
char timestamp[32];
+ bool suc = true;
int i, count;
- FILE *out = stdout;
- fprintf(out, "\033[H\033[J");
+ /* Clear terminal screen */
+ suc &= BOOL_FPRINT(out, "\033[H\033[J");
+
/* PSI output (one-line, no cat style) */
- fprintf(out, "System Pressure Information: ");
- fprintf(out, "(avg10/avg60/avg300/total)\n");
- fprintf(out, "CPU:");
- fprintf(out, " full: %6.1f%%/%6.1f%%/%6.1f%%/%-10llu", psi.cpu_full_avg10,
- psi.cpu_full_avg60, psi.cpu_full_avg300, psi.cpu_full_total);
- fprintf(out, " some: %6.1f%%/%6.1f%%/%6.1f%%/%-10llu\n", psi.cpu_some_avg10,
- psi.cpu_some_avg60, psi.cpu_some_avg300, psi.cpu_some_total);
-
- fprintf(out, "Memory:");
- fprintf(out, " full: %6.1f%%/%6.1f%%/%6.1f%%/%-10llu", psi.memory_full_avg10,
- psi.memory_full_avg60, psi.memory_full_avg300, psi.memory_full_total);
- fprintf(out, " some: %6.1f%%/%6.1f%%/%6.1f%%/%-10llu\n", psi.memory_some_avg10,
- psi.memory_some_avg60, psi.memory_some_avg300, psi.memory_some_total);
-
- fprintf(out, "IO:");
- fprintf(out, " full: %6.1f%%/%6.1f%%/%6.1f%%/%-10llu", psi.io_full_avg10,
- psi.io_full_avg60, psi.io_full_avg300, psi.io_full_total);
- fprintf(out, " some: %6.1f%%/%6.1f%%/%6.1f%%/%-10llu\n", psi.io_some_avg10,
- psi.io_some_avg60, psi.io_some_avg300, psi.io_some_total);
- fprintf(out, "IRQ:");
- fprintf(out, " full: %6.1f%%/%6.1f%%/%6.1f%%/%-10llu\n\n", psi.irq_full_avg10,
- psi.irq_full_avg60, psi.irq_full_avg300, psi.irq_full_total);
+ suc &= BOOL_FPRINT(out, "System Pressure Information: (avg10/avg60/avg300/total)\n");
+ suc &= BOOL_FPRINT(out, PSI_LINE_FORMAT,
+ "CPU some:",
+ psi.cpu_some_avg10,
+ psi.cpu_some_avg60,
+ psi.cpu_some_avg300,
+ psi.cpu_some_total / 1000);
+ suc &= BOOL_FPRINT(out, PSI_LINE_FORMAT,
+ "CPU full:",
+ psi.cpu_full_avg10,
+ psi.cpu_full_avg60,
+ psi.cpu_full_avg300,
+ psi.cpu_full_total / 1000);
+ suc &= BOOL_FPRINT(out, PSI_LINE_FORMAT,
+ "Memory full:",
+ psi.memory_full_avg10,
+ psi.memory_full_avg60,
+ psi.memory_full_avg300,
+ psi.memory_full_total / 1000);
+ suc &= BOOL_FPRINT(out, PSI_LINE_FORMAT,
+ "Memory some:",
+ psi.memory_some_avg10,
+ psi.memory_some_avg60,
+ psi.memory_some_avg300,
+ psi.memory_some_total / 1000);
+ suc &= BOOL_FPRINT(out, PSI_LINE_FORMAT,
+ "IO full:",
+ psi.io_full_avg10,
+ psi.io_full_avg60,
+ psi.io_full_avg300,
+ psi.io_full_total / 1000);
+ suc &= BOOL_FPRINT(out, PSI_LINE_FORMAT,
+ "IO some:",
+ psi.io_some_avg10,
+ psi.io_some_avg60,
+ psi.io_some_avg300,
+ psi.io_some_total / 1000);
+ suc &= BOOL_FPRINT(out, PSI_LINE_FORMAT,
+ "IRQ full:",
+ psi.irq_full_avg10,
+ psi.irq_full_avg60,
+ psi.irq_full_avg300,
+ psi.irq_full_total / 1000);
+
if (cfg.container_path) {
- fprintf(out, "Container Information (%s):\n", cfg.container_path);
- fprintf(out, "Processes: running=%d, sleeping=%d, ",
+ suc &= BOOL_FPRINT(out, "Container Information (%s):\n", cfg.container_path);
+ suc &= BOOL_FPRINT(out, "Processes: running=%d, sleeping=%d, ",
container_stats.nr_running, container_stats.nr_sleeping);
- fprintf(out, "stopped=%d, uninterruptible=%d, io_wait=%d\n\n",
+ suc &= BOOL_FPRINT(out, "stopped=%d, uninterruptible=%d, io_wait=%d\n\n",
container_stats.nr_stopped, container_stats.nr_uninterruptible,
container_stats.nr_io_wait);
}
- fprintf(out, "Top %d processes (sorted by CPU delay):\n\n",
+ suc &= BOOL_FPRINT(out, "Top %d processes (sorted by CPU delay):\n",
cfg.max_processes);
- fprintf(out, " PID TGID COMMAND CPU(ms) IO(ms) ");
- fprintf(out, "SWAP(ms) RCL(ms) THR(ms) CMP(ms) WP(ms) IRQ(ms)\n");
- fprintf(out, "-----------------------------------------------");
- fprintf(out, "----------------------------------------------\n");
+ suc &= BOOL_FPRINT(out, "%5s %5s %-17s", "PID", "TGID", "COMMAND");
+ suc &= BOOL_FPRINT(out, "%7s %7s %7s %7s %7s %7s %7s %7s\n",
+ "CPU(ms)", "IO(ms)", "SWAP(ms)", "RCL(ms)",
+ "THR(ms)", "CMP(ms)", "WP(ms)", "IRQ(ms)");
+
+ 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++) {
- fprintf(out, "%5d %5d %-15s ",
+ suc &= BOOL_FPRINT(out, "%5d %5d %-15s",
tasks[i].pid, tasks[i].tgid, tasks[i].command);
- fprintf(out, "%7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f\n",
+ suc &= BOOL_FPRINT(out, "%7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f\n",
average_ms(tasks[i].cpu_delay_total, tasks[i].cpu_count),
average_ms(tasks[i].blkio_delay_total, tasks[i].blkio_count),
average_ms(tasks[i].swapin_delay_total, tasks[i].swapin_count),
@@ -712,7 +763,10 @@ static void display_results(void)
average_ms(tasks[i].irq_delay_total, tasks[i].irq_count));
}
- fprintf(out, "\n");
+ suc &= BOOL_FPRINT(out, "\n");
+
+ if (!suc)
+ perror("Error writing to output");
}
/* Main function */
--
2.25.1
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