Make dyntick work again

Hi all,

Here's a quick patch to make dyntick work on omap again after the clocksource changes. It now uses the Linux common implementation instead of the ARM specific one.

I haven't tested this patch much yet, except:

# grep time /proc/interrupts; sleep 10; grep time /proc/interrupts

Drops the ticks to below 10.

Regards,

Tony

index be7cb8e..1eaec1c 100644
@@ -146,6 +146,14 @@ static inline void omap_32k_timer_ack_irq(void)
 
 #endif
 
+static int omap_32k_timer_set_next_event(unsigned long delta,
+					 struct clock_event_device *dev)
+{
+	omap_32k_timer_start(delta);
+
+	return 0;
+}
+
 static void omap_32k_timer_set_mode(enum clock_event_mode mode,
 				    struct clock_event_device *evt)
 {

@@ -153,9 +161,9 @@ static void omap_32k_timer_set_mode(enum clock_event_mode mode,
 
 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
+	case CLOCK_EVT_MODE_ONESHOT:
 		omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
 		break;
-	case CLOCK_EVT_MODE_ONESHOT:
 	case CLOCK_EVT_MODE_UNUSED:
 	case CLOCK_EVT_MODE_SHUTDOWN:
 		break;

@@ -166,8 +174,9 @@ static void omap_32k_timer_set_mode(enum clock_event_mode mode,
 
 static struct clock_event_device clockevent_32k_timer = {
 	.name		= "32k-timer",
-	.features       = CLOCK_EVT_FEAT_PERIODIC,
+	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 	.shift		= 32,
+	.set_next_event	= omap_32k_timer_set_next_event,
 	.set_mode	= omap_32k_timer_set_mode,
 };
 

Hi,

Umm, there's a problem, I can't boot with timer32k. It halts at here.

<5>Linux version 2.6.23-omap1 (kmpark@party) (gcc version 3.4.4 (release) (Code7
CPU: ARMv6-compatible processor [4107b362] revision 2 (ARMv6TEJ), cr=00c5387f
Machine: OMAP24xx Apollon
Memory policy: ECC disabled, Data cache writeback
<7>On node 0 totalpages: 32768

<7>  DMA zone: 256 pages used for memmap
<7>  DMA zone: 0 pages reserved
<7>  DMA zone: 32512 pages, LIFO batch:7
<7>  Normal zone: 0 pages used for memmap
<7>  Movable zone: 0 pages used for memmap

<6>OMAP24204
<6>SRAM: Mapped pa 0x40200000 to va 0xd0000000 size: 0x100000
CPU0: D VIPT write-back cache
CPU0: I cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets
CPU0: D cache: 32768 bytes, associativity 4, 32 byte lines, 256 sets Built 1 zonelists in Zone order. Total pages: 32512
<5>Kernel command line: root=/dev/nfs rw mem=128M console=ttyS0,115200n8 ip=1922 <6>kernel profiling enabled (shift: 2)
<6>Clocking rate (Crystal/DPLL/MPU): 12.0/660/330 MHz
<6>GPMC revision 2.0
<6>IRQ: Found an INTC at 0xd80fe000 (revision 2.0) with 96 interrupts <6>Total of 96 interrupts on 1 active controller
<6>OMAP242x GPIO hardware version 1.8
PID hash table entries: 512 (order: 9, 2048 bytes)
Console: colour dummy device 80x30
<6>Dentry cache hash table entries: 16384 (order: 4, 65536 bytes) <6>Inode-cache hash table entries: 8192 (order: 3, 32768 bytes) <6>Memory: 128MB = 128MB total
<5>Memory: 124160KB available (2580K code, 303K data, 92K init) <7>Calibrating delay loop... 1.05 BogoMIPS (lpj=4096)
Mount-cache hash table entries: 512
<6>CPU: Testing write buffer coherency:

It's also can't boot 2.6.22, umm I will track this one.

Anyway, I used the mpu timer and here's the dyntick result. (mpu also support the oneshot in the code) Is it the right results?

/ # grep time /proc/interrupts ; sleep 10; grep time /proc/interrupts

 37:        714        INTC  gp timer
 37:        787        INTC  gp timer
/ # grep time /proc/interrupts ; sleep 10; grep time /proc/interrupts
 37:        880        INTC  gp timer
 37:        959        INTC  gp timer

Thank you,
Kyungmin Park

P.S., here's the current kernel configuration (timer 32k) CONFIG_GENERIC_TIME=y CONFIG_GENERIC_CLOCKEVENTS=y CONFIG_OMAP_32K_TIMER=y CONFIG_OMAP_32K_TIMER_HZ=128 CONFIG_OMAP_DM_TIMER=y
# Kernel Features
#
CONFIG_TICK_ONESHOT=y
CONFIG_NO_HZ=y
CONFIG_HIGH_RES_TIMERS=y
CONFIG_PREEMPT=y
CONFIG_HZ=128

On OMAP 5912 OSK I get:

...
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
NET: Registered protocol family 16
MUX: initialized M19_1610_CAM_RSTZ
...
MUX: initialized PWL
OMAP DMA hardware version 1
DMA capabilities: 000c0000:00000000:01ff:003f:007f Initializing OMAP McBSP system omap_dsp_init() done
USB: hmc 16, usb2 alt 0 wires
i2c_omap i2c_omap.1: bus 1 rev2.2 at 100 kHz
tps65010: version 2 May 2005
Time: 32k_counter clocksource has been installed. Switched to high resolution mode on CPU 0
NET: Registered protocol family 2
...

my config:

CONFIG_GENERIC_TIME=y
CONFIG_GENERIC_CLOCKEVENTS=y
# CONFIG_OMAP_MPU_TIMER is not set
CONFIG_OMAP_32K_TIMER=y
CONFIG_OMAP_32K_TIMER_HZ=128
# CONFIG_OMAP_DM_TIMER is not set

#
# Kernel Features
#
CONFIG_TICK_ONESHOT=y
CONFIG_NO_HZ=y
CONFIG_HIGH_RES_TIMERS=y
CONFIG_PREEMPT=y
CONFIG_HZ=128

As the "ok" in "CPU: Testing write buffer coherency: ok" is already missing in your output, maybe it is anything else?

Regards

Dirk

Sounds like it's working on omap1 then :)

Tony

Hi,

<snip>

Hmm, works on n800 which is 2420. Maybe it's some 2430 related issue?

Yes, (959 - 880) / 10 = 7 ticks per second. We should be able to get down to ~2 ticks per second with an idle system already, so sounds like there are some kernel timers running.

Time to try powertop on omap!

Tony

Hi,

Here is powertop running on 3430 using dynamic tick :) It would be nice to format the C state information such that it reports residency. Sometime in the future. It is directly useable for seeing timers. Not so many timers running on a full up NFS mounted system. It used to run fine on OMAP2 from GIT once clocksource came.

--------------------
< Detailed C-state information is only available on Mobile CPUs (laptops) >

Wakeups-from-idle per second : 13.1 interval: 10.0s

Top causes for wakeups:

  38.9% (  4.2)       <interrupt> : 32KHz timer
  29.6% (  3.2)       <interrupt> : eth0
   9.3% (  1.0)     <kernel core> : __netdev_watchdog_up (dev_watchdog)
   4.6% (  0.5)     <kernel core> : queue_delayed_work_on (delayed_work_timer_fn
   2.8% (  0.3)     <kernel core> : irlmp_start_discovery_timer (irlmp_discovery

_timer_expired)

[email protected]:/tst# uname -a
Linux 128.247.75.244 2.6.22.1-omap1 #3 Fri Oct 12 14:53:45 CDT 2007 armv7l GNU/L
inux
[email protected]:/tst# cat /proc/cpuinfo | grep OMAP
Hardware        : OMAP3430 sdp3430 board
[email protected]:/tst#
--------------------

Regards,
Richard W.

Great! Time to push that patch then. I also run a quick timer tests with select and sleep, and they're working just fine.

Tony