Hello,
Currently the code uses the per-cpu workqueue system_long_wq to schedule
long running works.
Unbound works could benefit from scheduler task placement, to optimize
performance and power consumption. Another good reason to have this unbound,
is the "queue_delayed_work()" function, used to enqueue the work item.
More details on this will follow in the next section.
Recently, a new unbound workqueue specific for long running work has been
added:
c116737e972e ("workqueue: Add system_dfl_long_wq for long unbound works")
~~~ Details about queue_delayed_work ~~~
system_long_wq is a per-cpu workqueue and it is used as a parameter of
queue_delayed_work(). This function schedule an item that it will later
be enqueued (once the timer will fire). __queue_delayed_work() does the job
receiving as "cpu" WORK_CPU_UNBOUND:
if (housekeeping_enabled(HK_TYPE_TIMER)) {
// [....]
} else {
if (likely(cpu == WORK_CPU_UNBOUND))
add_timer_global(timer);
else
add_timer_on(timer, cpu);
}
The timer is global, so can fire everywhere, and the work item will be
enqueued where the timer fired.
Since the workqueue work doesn't rely on per-cpu variables, there is no
obvious reason that justify the use of a per-cpu workqueue. So change the
workqueue with the new system_dfl_long_wq, so that the used workqueue is
now unbound and can benefit from scheduler task placement.
Thanks!
Marco Crivellari (5):
ibmvnic: Move long delayed work on system_dfl_long_wq
net: ti: icssg-stats: Move long delayed work on system_dfl_long_wq
net: thunderbolt: Move long delayed work on system_dfl_long_wq
net: usb: pegasus: Move long delayed work on system_dfl_long_wq
r8152: Move long delayed work on system_dfl_long_wq
drivers/net/ethernet/ibm/ibmvnic.c | 4 ++--
drivers/net/ethernet/ti/icssg/icssg_stats.c | 2 +-
drivers/net/thunderbolt/main.c | 7 ++++---
drivers/net/usb/pegasus.c | 9 +++++----
drivers/net/usb/r8152.c | 7 ++++---
5 files changed, 16 insertions(+), 13 deletions(-)
--
2.54.0