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MINOR: activity: collect time spent with a lock held for each task

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When DEBUG_THREAD > 0 and task profiling enabled, we'll now measure the
time spent with at least one lock held for each task. The time is
collected by locking operations when locks are taken raising the level
to one, or released resetting the level. An accumulator is updated in
the thread_ctx struct that is collected by the scheduler when the task
returns, and updated in the sched_activity entry of the related task.

This allows to observe figures like this one:

  Tasks activity over 259.516 sec till 0.000 sec ago:
    function                      calls   cpu_tot   cpu_avg   lkw_avg   lkd_avg   lat_avg
    h1_io_cb                   15466589   2.574m    9.984us      -         -      33.45us <- sock_conn_iocb@src/sock.c:1099 tasklet_wakeup
    sc_conn_io_cb               8047994   8.325s    1.034us      -         -      870.1us <- sc_app_chk_rcv_conn@src/stconn.c:844 tasklet_wakeup
    process_stream              7734689   4.356m    33.79us   1.990us   1.641us   1.554ms <- sc_notify@src/stconn.c:1206 task_wakeup
    process_stream              7734292   46.74m    362.6us   278.3us   132.2us   972.0us <- stream_new@src/stream.c:585 task_wakeup
    sc_conn_io_cb               7733158   46.88s    6.061us      -         -      68.78us <- h1_wake_stream_for_recv@src/mux_h1.c:3633 tasklet_wakeup
    task_process_applet         6603593   4.484m    40.74us   16.69us   34.00us   96.47us <- sc_app_chk_snd_applet@src/stconn.c:1043 appctx_wakeup
    task_process_applet         4761796   3.420m    43.09us   18.79us   39.28us   138.2us <- __process_running_peer_sync@src/peers.c:3579 appctx_wakeup
    process_table_expire        4710662   4.880m    62.16us   9.648us   53.95us   158.6us <- run_tasks_from_lists@src/task.c:671 task_queue
    stktable_add_pend_updates   4171868   6.786s    1.626us      -      1.487us   47.94us <- stktable_add_pend_updates@src/stick_table.c:869 tasklet_wakeup
    h1_io_cb                    2871683   1.198s    417.0ns   70.00ns   69.00ns   1.005ms <- h1_takeover@src/mux_h1.c:5659 tasklet_wakeup
    process_peer_sync           2304957   5.368s    2.328us      -      1.156us   68.54us <- stktable_add_pend_updates@src/stick_table.c:873 task_wakeup
    process_peer_sync           1388141   3.174s    2.286us      -      1.130us   52.31us <- run_tasks_from_lists@src/task.c:671 task_queue
    stktable_add_pend_updates    463488   3.530s    7.615us   2.000ns   7.134us   771.2us <- stktable_touch_with_exp@src/stick_table.c:654 tasklet_wakeup

Here we see that almost the entirety of stktable_add_pend_updates() is
spent under a lock, that 1/3 of the execution time of process_stream()
was performed under a lock and that 2/3 of it was spent waiting for a
lock (this is related to the 10 track-sc present in this config), and
that the locking time in process_peer_sync() has now significantly
reduced. This is more visible with "show profiling tasks aggr":

  Tasks activity over 475.354 sec till 0.000 sec ago:
    function                      calls   cpu_tot   cpu_avg   lkw_avg   lkd_avg   lat_avg
    h1_io_cb                   25742539   3.699m    8.622us   11.00ns   10.00ns   188.0us
    sc_conn_io_cb              22565666   1.475m    3.920us      -         -      473.9us
    process_stream             21665212   1.195h    198.6us   140.6us   67.08us   1.266ms
    task_process_applet        16352495   11.31m    41.51us   17.98us   36.55us   112.3us
    process_peer_sync           7831923   17.15s    2.189us      -      1.107us   41.27us
    process_table_expire        6878569   6.866m    59.89us   9.359us   51.91us   151.8us
    stktable_add_pend_updates   6602502   14.77s    2.236us      -      2.060us   119.8us
    h1_timeout_task                 801   703.4us   878.0ns      -         -      185.7us
    srv_cleanup_toremove_conns      347   12.43ms   35.82us   240.0ns   70.00ns   1.924ms
    accept_queue_process            142   1.384ms   9.743us      -         -      340.6us
    srv_cleanup_idle_conns           74   475.0us   6.418us   896.0ns   5.667us   114.6us
This commit is contained in:
Willy Tarreau 2025-09-11 11:26:40 +02:00
parent 95433f224e
commit 98cc815e3e
3 changed files with 23 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
include/haproxy/thread.h
View File

@ -368,17 +368,31 @@ static inline unsigned long thread_isolated()
lock_start = now_mono_time(); \
} \
(void)(expr); \
if (_LK_ == _LK_UN) \
if (_LK_ == _LK_UN) { \
th_ctx->lock_level += bal; \
else if (unlikely(lock_start)) \
th_ctx->lock_wait_total += now_mono_time() - lock_start; \
if (th_ctx->lock_level == 0 && unlikely(th_ctx->flags & TH_FL_TASK_PROFILING)) \
th_ctx->locked_total += now_mono_time() - th_ctx->lock_start_date; \
} else if (unlikely(th_ctx->flags & TH_FL_TASK_PROFILING)) { \
uint64_t now = now_mono_time(); \
if (lock_start) \
th_ctx->lock_wait_total += now - lock_start; \
if (th_ctx->lock_level == 1) \
th_ctx->lock_start_date = now; \
} \
if (lbl != OTHER_LOCK) \
_lock_wait_common(_LK_, lbl); \
} while (0)
#define _lock_cond(_LK_, bal, lbl, expr) ({ \
typeof(expr) _expr = (expr); \
if (_expr == 0) \
if (_expr == 0) { \
th_ctx->lock_level += bal; \
if (unlikely(th_ctx->flags & TH_FL_TASK_PROFILING)) { \
if (_LK_ == _LK_UN && th_ctx->lock_level == 0) \
th_ctx->locked_total += now_mono_time() - th_ctx->lock_start_date; \
else if (_LK_ != _LK_UN && th_ctx->lock_level == 1) \
th_ctx->lock_start_date = now_mono_time(); \
} \
} \
if (lbl != OTHER_LOCK && !_expr) \
_lock_wait_common(_LK_, lbl); \
_expr; \

2
include/haproxy/tinfo-t.h
View File

@ -161,6 +161,8 @@ struct thread_ctx {
uint32_t sched_wake_date; /* current task/tasklet's wake date in 32-bit ns or 0 if not supported */
uint64_t sched_call_date; /* current task/tasklet's call date in ns */
uint64_t lock_wait_total; /* total time in ns spent waiting for a lock (task prof) */
uint64_t lock_start_date; /* date when first locked was obtained (task prof) */
uint64_t locked_total; /* total time in ns spent with at least one lock held (task prof) */
uint64_t prev_mono_time; /* previous system wide monotonic time (leaving poll) */
uint64_t curr_mono_time; /* latest system wide monotonic time (leaving poll) */

3
src/task.c
View File

@ -570,6 +570,7 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
t->calls++;
th_ctx->lock_wait_total = 0;
th_ctx->locked_total = 0;
th_ctx->sched_wake_date = t->wake_date;
if (th_ctx->sched_wake_date || (t->state & TASK_F_WANTS_TIME)) {
/* take the most accurate clock we have, either
@ -683,6 +684,8 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
HA_ATOMIC_ADD(&profile_entry->cpu_time, (uint32_t)(now_mono_time() - th_ctx->sched_call_date));
if (th_ctx->lock_wait_total)
HA_ATOMIC_ADD(&profile_entry->lkw_time, th_ctx->lock_wait_total);
if (th_ctx->locked_total)
HA_ATOMIC_ADD(&profile_entry->lkd_time, th_ctx->locked_total);
}
}
th_ctx->current_queue = -1;