tty: Use unbound workqueue for all input workers
authorPeter Hurley <peter@hurleysoftware.com>
Sat, 17 Oct 2015 20:36:24 +0000 (16:36 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 18 Oct 2015 04:32:21 +0000 (21:32 -0700)
commite052c6d15c61cc4caff2f06cbca72b183da9f15e
tree833a650c7a1fa3581416b433adbaa890dbe31962
parente176058f0de53c2346734e5254835e0045364001
tty: Use unbound workqueue for all input workers

The commonly accepted wisdom that scheduling work on the same cpu
that handled interrupt i/o benefits from cache-locality is only
true if the cpu is idle (since bound kworkers are often the highest
vruntime and thus the lowest priority).

Measurements of scheduling via the unbound queue show lowered
worst-case latency responses of up to 5x over bound workqueue, without
increase in average latency or throughput.

pty i/o test measurements show >3x (!) reduced total running time; tests
previously taking ~8s now complete in <2.5s.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/tty_buffer.c