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MINOR: tasklet: support an optional set of wakeup flags to tasklet_wakeup_on()

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tasklet_wakeup_on() and its derivates (tasklet_wakeup_after() and
tasklet_wakeup()) do not support passing a wakeup cause like
task_wakeup(). This is essentially due to an API limitation cause by
the fact that for a very long time the only reason for waking up was
to process pending I/O. But with the growing complexity of mux tasks,
it is becoming important to be able to skip certain heavy processing
when not strictly needed.

One possibility is to permit the caller of tasklet_wakeup() to pass
flags like task_wakeup(). Instead of going with a complex naming scheme,
let's simply make the flags optional and be zero when not specified. This
means that tasklet_wakeup_on() now takes either 2 or 3 args, and that the
third one is the optional flags to be passed to the callee. Eligible flags
are essentially the non-persistent ones (TASK_F_UEVT* and TASK_WOKEN_*)
which are cleared when the tasklet is executed. This way the handler
will find them in its <state> argument and will be able to distinguish
various causes for the call.
This commit is contained in:
Willy Tarreau
2024-11-19 15:56:59 +01:00
parent 0334cb28a9
commit 12fcd65468
2 changed files with 33 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
doc/internals/api/scheduler.txt
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@@ -98,12 +98,14 @@ void task_set_thread(t, id)
indicate "any thread". It's ignored and replaced by zero when threads
are disabled.
void tasklet_wakeup(tl)
void tasklet_wakeup(tl, [flags])
Make sure that tasklet <tl> will wake up, that is, will execute at
least once. The tasklet will run on its assigned thread, or on any
thread if its TID is negative.
thread if its TID is negative. An optional <flags> value may be passed
to set a wakeup cause on the tasklet's flags, typically TASK_WOKEN_* or
TASK_F_UEVT*. When not set, 0 is passed (i.e. no flags are changed).
struct list *tasklet_wakeup_after(head, tl)
struct list *tasklet_wakeup_after(head, tl, [flags])
Schedule tasklet <tl> to run immediately the current one if <head> is
NULL, or after the last queued one if <head> is non-null. The new head
is returned, to be passed to the next call. The purpose here is to
@@ -113,15 +115,20 @@ struct list *tasklet_wakeup_after(head, tl)
already queued tasklets. This may induce extra latencies for pending
jobs and must only be used extremely carefully when it's certain that
the processing will benefit from using fresh data from the L1 cache.
An optional <flags> value may be passed to set a wakeup cause on the
tasklet's flags, typically TASK_WOKEN_* or TASK_F_UEVT*. When not set,
0 is passed (i.e. no flags are changed).
void tasklet_wakeup_on(tl, thr)
void tasklet_wakeup_on(tl, thr, [flags])
Make sure that tasklet <tl> will wake up on thread <thr>, that is, will
execute at least once. The designated thread may only differ from the
calling one if the tasklet is already configured to run on another
thread, and it is not permitted to self-assign a tasklet if its tid is
negative, as it may already be scheduled to run somewhere else. Just in
case, only use tasklet_wakeup() which will pick the tasklet's assigned
thread ID.
thread ID. An optional <flags> value may be passed to set a wakeup
cause on the tasklet's flags, typically TASK_WOKEN_* or TASK_F_UEVT*.
When not set, 0 is passed (i.e. no flags are changed).
struct tasklet *tasklet_new()
Allocate a new tasklet and set it to run by default on the calling