Re: [PATCH] OMAP CPUIDLE: CPU Idle latency measurement

Hi Vishwa,

On 8/28/2010 12:08 AM, vishwanath.sripathy@linaro.org wrote:

From: Vishwanath BSvishwanath.sripathy@linaro.org

This patch has instrumentation code for measuring latencies for various CPUIdle C states for OMAP. Idea here is to capture the timestamp at various phases of CPU Idle and then compute the sw latency for various c states. For OMAP, 32k clock is chosen as reference clock this as is an always on clock. wkup domain memory (scratchpad memory) is used for storing timestamps. One can see the worstcase latencies in below sysfs entries (after enabling CONFIG_CPU_IDLE_PROF in .config). This information can be used to correctly configure cpu idle latencies for various C states after adding HW latencies for each of these sw latencies. /sys/devices/system/cpu/cpu0/cpuidle/state<n>/actual_latency /sys/devices/system/cpu/cpu0/cpuidle/state<n>/sleep_latency /sys/devices/system/cpu/cpu0/cpuidle/state<n>/wkup_latency

FYI, Jean is currently working on using standard Linux probes in order to instrument CPUIdle / CPUfreq. I'm not sure it is doable, but it might better to use standard method to do that instead of purely OMAP3 specific stuff. This code will not scale easily on OMAP4.

Do you have a dump of the latency you measured do far?

THis patch is tested on OMAP ZOOM3 using kevin's pm branch.

Signed-off-by: Vishwanath BSvishwanath.sripathy@linaro.org Cc: linaro-dev@lists.linaro.org

---

arch/arm/mach-omap2/cpuidle34xx.c | 58 ++++++++++++++++-- arch/arm/mach-omap2/pm.h | 5 ++ arch/arm/mach-omap2/sleep34xx.S | 121 +++++++++++++++++++++++++++++++++++++ drivers/cpuidle/Kconfig | 5 ++ drivers/cpuidle/sysfs.c | 16 +++++- include/linux/cpuidle.h | 3 + 6 files changed, 202 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c index 3d3d035..398bef8 --- a/arch/arm/mach-omap2/cpuidle34xx.c +++ b/arch/arm/mach-omap2/cpuidle34xx.c @@ -25,6 +25,7 @@ #include<linux/sched.h> #include<linux/cpuidle.h>

+#include<linux/clk.h> #include<plat/prcm.h> #include<plat/irqs.h> #include<plat/powerdomain.h> @@ -86,6 +87,11 @@ static struct cpuidle_params cpuidle_params_table[] = { {1, 10000, 30000, 300000}, };

+#ifdef CONFIG_CPU_IDLE_PROF

Cannot you use _PROFILING instead? _PROF does not sound very meaningful for my point of view.

+static struct clk *clk_32k; +#define CONVERT_32K_USEC(lat) (lat * (USEC_PER_SEC/clk_get_rate(clk_32k))) +#endif

• static int omap3_idle_bm_check(void) { if (!omap3_can_sleep())

@@ -115,21 +121,28 @@ static int _cpuidle_deny_idle(struct powerdomain *pwrdm,

• Called from the CPUidle framework to program the device to the
• specified target state selected by the governor.

*/

• static int omap3_enter_idle(struct cpuidle_device *dev, struct cpuidle_state *state) { struct omap3_processor_cx *cx = cpuidle_get_statedata(state); struct timespec ts_preidle, ts_postidle, ts_idle; u32 mpu_state = cx->mpu_state, core_state = cx->core_state;

+#ifdef CONFIG_CPU_IDLE_PROF

•   int idle_time, latency;
  

•   long sleep_time, wkup_time, total_sleep_time;
  

•   long preidle_time, postidle_time;
  

+#endif

     current_cx_state = *cx;

•   /* Used to keep track of the total time in idle */
  

•   getnstimeofday(&ts_preidle);
  

•    local_irq_disable();
     local_fiq_disable();
  

•   /* Used to keep track of the total time in idle */
  

•   getnstimeofday(&ts_preidle);
  

+#ifdef CONFIG_CPU_IDLE_PROF

•   preidle_time = omap3_sram_get_32k_tick();
  

+#endif pwrdm_set_next_pwrst(mpu_pd, mpu_state); pwrdm_set_next_pwrst(core_pd, core_state);

@@ -153,9 +166,39 @@ return_sleep_time: getnstimeofday(&ts_postidle); ts_idle = timespec_sub(ts_postidle, ts_preidle);

+#ifdef CONFIG_CPU_IDLE_PROF

•   postidle_time = omap3_sram_get_32k_tick();
  

+#endif local_irq_enable(); local_fiq_enable();

+#ifdef CONFIG_CPU_IDLE_PROF

•   sleep_time = omap3_sram_get_sleep_time();
  

•   wkup_time = omap3_sram_get_wkup_time();
  

•   /* take care of overflow */
  

•   if (postidle_time<  preidle_time)
  

•           postidle_time += (u32) 0xffffffff;
  

•   if (wkup_time<  sleep_time)
  

•           wkup_time += (u32) 0xffffffff;
  

•   idle_time = postidle_time - preidle_time;
  

•   total_sleep_time = wkup_time -  sleep_time;
  

•   latency = idle_time - total_sleep_time;
  

•   sleep_time = omap3_sram_get_sleep_time();
  

•   wkup_time = omap3_sram_get_wkup_time();
  

•   /* calculate average latency after ignoring sprious ones */
  

•   if ((total_sleep_time>  0)&&  (latency>  state->actual_latency)
  

+&& (latency>= 0)) {

•           state->actual_latency = CONVERT_32K_USEC(latency);
  

•           latency = (sleep_time - preidle_time);
  

•           state->sleep_latency = CONVERT_32K_USEC(latency);
  

•           latency = postidle_time - wkup_time;
  

•           state->wkup_latency = CONVERT_32K_USEC(latency);
  

•   }
  

+#endif

•    return ts_idle.tv_nsec / NSEC_PER_USEC + ts_idle.tv_sec * USEC_PER_SEC;
  

  }

@@ -423,7 +466,9 @@ int __init omap3_idle_init(void) struct omap3_processor_cx *cx; struct cpuidle_state *state; struct cpuidle_device *dev;

+#ifdef CONFIG_CPU_IDLE_PROF

•   static struct device dummy_device;
  

+#endif mpu_pd = pwrdm_lookup("mpu_pwrdm"); core_pd = pwrdm_lookup("core_pwrdm");

@@ -456,6 +501,9 @@ int __init omap3_idle_init(void)

     omap3_cpuidle_update_states();

+#ifdef CONFIG_CPU_IDLE_PROF

•   clk_32k = clk_get(&dummy_device, "wkup_32k_fck");
  

+#endif if (cpuidle_register_device(dev)) { printk(KERN_ERR "%s: CPUidle register device failed\n", __func__); diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h index 3de6ece..e62e87d 100644 --- a/arch/arm/mach-omap2/pm.h +++ b/arch/arm/mach-omap2/pm.h @@ -82,4 +82,9 @@ extern unsigned int save_secure_ram_context_sz; extern unsigned int omap24xx_cpu_suspend_sz; extern unsigned int omap34xx_cpu_suspend_sz;

+#ifdef CONFIG_CPU_IDLE_PROF +extern u32 omap3_sram_get_wkup_time(); +extern u32 omap3_sram_get_sleep_time(); +extern u32 omap3_sram_get_32k_tick(); +#endif #endif diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S index d522cd7..8dec5ef 100644 --- a/arch/arm/mach-omap2/sleep34xx.S +++ b/arch/arm/mach-omap2/sleep34xx.S @@ -59,6 +59,20 @@ #define SDRC_DLLA_STATUS_V OMAP34XX_SDRC_REGADDR(SDRC_DLLA_STATUS) #define SDRC_DLLA_CTRL_V OMAP34XX_SDRC_REGADDR(SDRC_DLLA_CTRL)

+#define TIMER_32K_SYNC_P 0x48320010 +#define TIMER_32K_SYNC OMAP2_L4_IO_ADDRESS(TIMER_32K_SYNC_P)

We are trying to get rid of all the direct usage of physical address and hard coded virtual address translation in the code. So please do not access the timer like that.

+#define SCRATCHPAD_SLEEP_TIME_OFFSET 0x9f8 +#define SCRATCHPAD_WKUP_TIME_OFFSET 0x9fc +#define SCRATCHPAD_SLEEP_TIME OMAP343X_CTRL_REGADDR(SCRATCHPAD_SLEEP_TIME_OFFSET) +#define SCRATCHPAD_WKUP_TIME OMAP343X_CTRL_REGADDR(SCRATCHPAD_WKUP_TIME_OFFSET) +#define SCRATCHPAD_WKUP_TIME_P OMAP343X_CTRL_BASE + SCRATCHPAD_WKUP_TIME_OFFSET

+#define CM_ICLKEN_WKUP OMAP34XX_CM_REGADDR(WKUP_MOD, CM_ICLKEN) +#define CM_ICLKEN_WKUP_P OMAP3430_CM_BASE + WKUP_MOD + CM_ICLKEN +#define CM_IDLEST_WKUP OMAP34XX_CM_REGADDR(WKUP_MOD, CM_IDLEST) +#define CM_IDLEST_WKUP_P OMAP3430_CM_BASE + WKUP_MOD + CM_IDLEST

Same issue, do not use any macros based on OMAP2_L4_IO_ADDRESS translation macros.

•     .text
  

  /* Function to aquire the semaphore in scratchpad */ ENTRY(lock_scratchpad_sem)

@@ -183,7 +197,31 @@ api_params: .word 0x4, 0x0, 0x0, 0x1, 0x1 ENTRY(save_secure_ram_context_sz) .word . - save_secure_ram_context +#ifdef CONFIG_CPU_IDLE_PROF +ENTRY(omap3_sram_get_wkup_time)

• stmfd sp!, {lr} @ save registers on stack

Not needed in your case, you are not using lr in your code.

•   ldr r0, wkup_time
  

•   ldr r0, [r0]
  

• ldmfd sp!, {pc} @ restore regs and return

Not needed either.

+ENTRY(omap3_sram_get_wkup_time_sz)

•    .word   . - omap3_sram_get_wkup_time
  

+ENTRY(omap3_sram_get_sleep_time)

• stmfd sp!, {lr} @ save registers on stack

Ditto

•   ldr r0, sleep_time
  

•   ldr r0, [r0]
  

• ldmfd sp!, {pc} @ restore regs and return

Ditto

+ENTRY(omap3_sram_get_sleep_time_sz)

•    .word   . - omap3_sram_get_sleep_time
  
  

+ENTRY(omap3_sram_get_32k_tick)

• stmfd sp!, {lr} @ save registers on stack

Ditto

•   ldr r0, sync_32k_timer
  

•   ldr r0, [r0]
  

• ldmfd sp!, {pc} @ restore regs and return

Ditto

+ENTRY(omap3_sram_get_32k_tick_sz)

•    .word   . - omap3_sram_get_32k_tick
  

+#endif

Why do you need assembly code to do that? Cannot you access directly these variable from the C code?

/*

• Forces OMAP into idle state

@@ -207,6 +245,13 @@ loop: cmp r1, #0x0 /* If context save is required, do that and execute wfi */ bne save_context_wfi

+#ifdef CONFIG_CPU_IDLE_PROF

•   ldr r4, sync_32k_timer
  

•   ldr     r5, [r4]
  

•   ldr r6, sleep_time
  

•   str r5, [r6]
  

+#endif /* Data memory barrier and Data sync barrier */ mov r1, #0 mcr p15, 0, r1, c7, c10, 4 @@ -224,8 +269,25 @@ loop: nop nop nop +#ifdef CONFIG_CPU_IDLE_PROF

•   ldr r4, iclken_wkup
  

•   ldr r5, [r4]
  

•   orr r5, r5, #0x4
  

•   str r5, [r4]
  

•   ldr r4, idlest_wkup
  

+wait_idlest:

•   ldr r5, [r4]
  

•   and     r5, r5, #0x4
  

•   cmp     r5, #0x0
  

•   bne     wait_idlest
  

•   ldr r4, sync_32k_timer
  

•   ldr     r5, [r4]
  

•   ldr r6, wkup_time
  

•   str r5, [r6]
  

+#endif

What are you trying to do exactly in that case? Could you describe that a little bit?

Regards, Benoit

     bl wait_sdrc_ok

•    ldmfd   sp!, {r0-r12, pc}               @ restore regs and return
  

  restore_es3: /*b restore_es3*/ @ Enable to debug restore code

@@ -247,6 +309,23 @@ copy_to_sram: blx r1 restore: /* b restore*/ @ Enable to debug restore code +#ifdef CONFIG_CPU_IDLE_PROF

•   ldr r4, iclken_wkup_p
  

•   ldr r5, [r4]
  

•   orr r5, r5, #0x4
  

•   str r5, [r4]
  

•   ldr r4, idlest_wkup_p
  

+wait_idlest1:

•   ldr r5, [r4]
  

•   and     r5, r5, #0x4
  

•   cmp     r5, #0x0
  

•   bne     wait_idlest1
  

•   ldr r4, sync_32k_timer_p
  

•   ldr r5, [r4]
  

•   ldr r6, wkup_time_p
  

•   str r5, [r6]
  

+#endif

•     /* Check what was the reason for mpu reset and store the reason in r9*/
      /* 1 - Only L1 and logic lost */
      /* 2 - Only L2 lost - In this case, we wont be here */
  

@@ -587,6 +666,12 @@ finished: mcr p15, 2, r10, c0, c0, 0 isb skip_l2_inval: +#ifdef CONFIG_CPU_IDLE_PROF

•   ldr r4, sync_32k_timer
  

•   ldr     r5, [r4]
  

•   ldr r6, sleep_time
  

•   str r5, [r6]
  

+#endif /* Data memory barrier and Data sync barrier */ mov r1, #0 mcr p15, 0, r1, c7, c10, 4 @@ -603,6 +688,22 @@ skip_l2_inval: nop nop nop +#ifdef CONFIG_CPU_IDLE_PROF

•   ldr r4, iclken_wkup
  

•   ldr r5, [r4]
  

•   orr r5, r5, #0x4
  

•   str r5, [r4]
  

•   ldr r4, idlest_wkup
  

+wait_idlest2:

•   ldr r5, [r4]
  

•   and     r5, r5, #0x4
  

•   cmp     r5, #0x0
  

•   bne     wait_idlest2
  

•   ldr r4, sync_32k_timer
  

•   ldr     r5, [r4]
  

•   ldr r6, wkup_time
  

•   str r5, [r6]
  

+#endif bl wait_sdrc_ok /* restore regs and return */ ldmfd sp!, {r0-r12, pc} @@ -668,5 +769,25 @@ cache_pred_disable_mask: .word 0xFFFFE7FB control_stat: .word CONTROL_STAT +#ifdef CONFIG_CPU_IDLE_PROF +sync_32k_timer:

•   .word TIMER_32K_SYNC
  

+sync_32k_timer_p:

•   .word TIMER_32K_SYNC_P
  

+sleep_time:

•   .word SCRATCHPAD_SLEEP_TIME
  

+wkup_time:

•   .word SCRATCHPAD_WKUP_TIME
  

+wkup_time_p:

•   .word SCRATCHPAD_WKUP_TIME_P
  

+iclken_wkup:

•   .word CM_ICLKEN_WKUP
  

+iclken_wkup_p:

•   .word CM_ICLKEN_WKUP_P
  

+idlest_wkup:

•   .word CM_IDLEST_WKUP
  

+idlest_wkup_p:

•   .word CM_IDLEST_WKUP_P
  

+#endif ENTRY(omap34xx_cpu_suspend_sz) .word . - omap34xx_cpu_suspend diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig index 7dbc4a8..147456d 100644 --- a/drivers/cpuidle/Kconfig +++ b/drivers/cpuidle/Kconfig @@ -18,3 +18,8 @@ config CPU_IDLE_GOV_MENU bool depends on CPU_IDLE&& NO_HZ default y

+config CPU_IDLE_PROF

•   bool
  

•   depends on CPU_IDLE
  

•   default n
  

diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c index 0310ffa..a3e9db1 100644 --- a/drivers/cpuidle/sysfs.c +++ b/drivers/cpuidle/sysfs.c @@ -249,6 +249,11 @@ define_show_state_ull_function(usage) define_show_state_ull_function(time) define_show_state_str_function(name) define_show_state_str_function(desc) +#ifdef CONFIG_CPU_IDLE_PROF +define_show_state_function(actual_latency) +define_show_state_function(sleep_latency) +define_show_state_function(wkup_latency) +#endif

define_one_state_ro(name, show_state_name); define_one_state_ro(desc, show_state_desc); @@ -256,7 +261,11 @@ define_one_state_ro(latency, show_state_exit_latency); define_one_state_ro(power, show_state_power_usage); define_one_state_ro(usage, show_state_usage); define_one_state_ro(time, show_state_time);

+#ifdef CONFIG_CPU_IDLE_PROF +define_one_state_ro(actual_latency, show_state_actual_latency); +define_one_state_ro(sleep_latency, show_state_sleep_latency); +define_one_state_ro(wkup_latency, show_state_wkup_latency); +#endif static struct attribute *cpuidle_state_default_attrs[] = { &attr_name.attr, &attr_desc.attr, @@ -264,6 +273,11 @@ static struct attribute *cpuidle_state_default_attrs[] = { &attr_power.attr, &attr_usage.attr, &attr_time.attr, +#ifdef CONFIG_CPU_IDLE_PROF +&attr_actual_latency.attr, +&attr_sleep_latency.attr, +&attr_wkup_latency.attr, +#endif NULL };

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 55215cc..6474f6a 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -43,6 +43,9 @@ struct cpuidle_state {

     int (*enter)    (struct cpuidle_device *dev,
                      struct cpuidle_state *state);

+#ifdef CONFIG_CPU_IDLE_PROF

•   u32 actual_latency, sleep_latency, wkup_latency;
  

+#endif };

/* Idle State Flags */

1.7.0.4

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