linux_dsm_epyc7002/include
Takashi Iwai 88452da92b ALSA: hda: Use standard waitqueue for RIRB wakeup
The HD-audio CORB/RIRB communication was programmed in a way that was
documented in the reference in decades ago, which is essentially a
polling in the waiter side.  It's working fine but costs CPU cycles on
some platforms that support only slow communications.  Also, for some
platforms that had unreliable communications, we put longer wait time
(2 ms), which accumulate quite long time if you execute many verbs in
a shot (e.g. at the initialization or resume phase).

This patch attempts to improve the situation by introducing the
standard waitqueue in the RIRB waiter side instead of polling.  The
test results on my machine show significant improvements.  The time
spent for "cat /proc/asound/card*/codec#*" were changed like:

* Intel SKL + Realtek codec
  before the patch:
   0.00user 0.04system 0:00.10elapsed 40.0%CPU
  after the patch:
   0.00user 0.01system 0:00.10elapsed 10.0%CPU

* Nvidia GP107GL + Nvidia HDMI codec
  before the patch:
   0.00user 0.00system 0:02.76elapsed 0.0%CPU
  after the patch:
   0.00user 0.00system 0:00.01elapsed 17.0%CPU

So, for Intel chips, the total time is same, while the total time is
greatly reduced (from 2.76 to 0.01s) for Nvidia chips.
The only negative data here is the increase of CPU time for Nvidia,
but this is the unavoidable cost for faster wakeups, supposedly.

Link: https://lore.kernel.org/r/20191210145727.22054-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2019-12-10 18:22:46 +01:00
..
acpi Merge branches 'acpi-utils', 'acpi-platform', 'acpi-video' and 'acpi-doc' 2019-11-26 10:30:49 +01:00
asm-generic powerpc updates for 5.5 #2 2019-12-06 13:36:31 -08:00
clocksource
crypto
drm mm + drm coherent memory support for vmwgfx 2019-11-30 09:38:11 -08:00
dt-bindings ARM: Device-tree updates 2019-12-05 12:09:47 -08:00
keys powerpc updates for 5.5 2019-11-30 14:35:43 -08:00
kunit
kvm
linux Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-08 13:28:11 -08:00
math-emu
media drm main pull for 5.5-rc1 2019-11-27 17:45:48 -08:00
misc
net inet: protect against too small mtu values. 2019-12-07 11:55:11 -08:00
pcmcia
ras
rdma hmm related patches for 5.5 2019-11-30 10:33:14 -08:00
scsi
soc drm msm + fixes for 5.5-rc1 2019-12-06 10:28:09 -08:00
sound ALSA: hda: Use standard waitqueue for RIRB wakeup 2019-12-10 18:22:46 +01:00
target
trace This is a relatively quiet cycle for nfsd, mainly various bugfixes. 2019-12-07 16:56:00 -08:00
uapi Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2019-12-07 18:33:01 -08:00
vdso
video
xen dma-mapping updates for 5.5-rc1 2019-11-28 11:16:43 -08:00