This is a note to let you know that I've just added the patch titled
ALSA: HDA: Lessen CPU usage when waiting for chip to respond
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
alsa-hda-lessen-cpu-usage-when-waiting-for-chip-to-respond.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 32cf4023e689ad5b3a81a749d8cc99d7f184cb99 Mon Sep 17 00:00:00 2001
From: David Henningsson <[email protected]>
Date: Fri, 4 May 2012 11:05:55 +0200
Subject: ALSA: HDA: Lessen CPU usage when waiting for chip to respond
From: David Henningsson <[email protected]>
commit 32cf4023e689ad5b3a81a749d8cc99d7f184cb99 upstream.
When an IRQ for some reason gets lost, we wait up to a second using
udelay, which is CPU intensive. This patch improves the situation by
waiting about 30 ms in the CPU intensive mode, then stepping down to
using msleep(2) instead. In essence, we trade some granularity in
exchange for less CPU consumption when the waiting time is a bit longer.
As a result, PulseAudio should no longer be killed by the kernel
for taking up to much RT-prio CPU time. At least not for *this* reason.
Signed-off-by: David Henningsson <[email protected]>
Tested-by: Arun Raghavan <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
sound/pci/hda/hda_intel.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -702,11 +702,13 @@ static unsigned int azx_rirb_get_respons
{
struct azx *chip = bus->private_data;
unsigned long timeout;
+ unsigned long loopcounter;
int do_poll = 0;
again:
timeout = jiffies + msecs_to_jiffies(1000);
- for (;;) {
+
+ for (loopcounter = 0;; loopcounter++) {
if (chip->polling_mode || do_poll) {
spin_lock_irq(&chip->reg_lock);
azx_update_rirb(chip);
@@ -722,7 +724,7 @@ static unsigned int azx_rirb_get_respons
}
if (time_after(jiffies, timeout))
break;
- if (bus->needs_damn_long_delay)
+ if (bus->needs_damn_long_delay || loopcounter > 3000)
msleep(2); /* temporary workaround */
else {
udelay(10);
Patches currently in stable-queue which might be from
[email protected] are
queue-3.0/alsa-hda-lessen-cpu-usage-when-waiting-for-chip-to-respond.patch
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