On 6/3/2011 8:14 AM, Menon, Nishanth wrote:
On Thu, Jun 2, 2011 at 09:51, Santosh Shilimkar
<santosh.shilimkar@xxxxxx> wrote:
Current OMAP2PLUS CPUfreq tagret() functions returns when all
the CPU's are not online. This will break DVFS when secondary
CPUs are offlined.
The intention of that check was just avoid CPU frequency change
during the window when CPU becomes online but it's cpufreq_init is
not done yet.
is it this requirement a boot requirement or a necessity for
cpufreq_driver.init being called for online cpus? Since we maintain
just a single freq_table... why do we care about multiple cpu_inits?
I put a comment after ---
After some thinking, I realised
there is no need of that since this is just a counter which
maintains the count for online_cpus = cpufreq_init_cpus.
And we need inits on all CPUs to ensure the CPU relation is
set. It's not all about _one_ table.
Anyways, tried testing this and .config with CONFIG_SMP_ON_UP and
USERSPACE. it works with one cpu and does not scale 2 cpus :(
You mean userspace governor? I don't think why that can happen.
Vishwa tested this and it did worked. We will test this again.
After applying this patch on kevin's cpufreq branch, I added some
prints for logging:
[..]
/* FIXME: what's the actual transition time? */
@@ -212,6 +220,8 @@ static int omap_cpu_exit(struct cpufreq_policy *policy)
if (is_smp()) {
cpus_initialized--;
smp_wmb();
+ pr_err("%s: cpu %d cpus_initialized = %d online=%d\n", __func__,
+ policy->cpu, cpus_initialized, num_online_cpus());
}
return 0;
}
on boot, this is what I see:
[ 0.421020] omap_cpu_init: cpu 0 cpus_initialized = 1 online=2
[ 0.421264] omap_target: cpu 0 not ready to go to 1008000 (inits=1
vs online=2)
[ 0.421630] omap_cpu_init: cpu 1 cpus_initialized = 2 online=2
[ 0.421691] omap_cpu_exit: cpu 1 cpus_initialized = 1 online=2
This must be becasue hot-plug governor is kicking in here which
is taking CPU1 in and OUT.
...
snip
...
[ 2.044128] omap_target: cpu 0 not ready to go to 1008000 (inits=1
vs online=2)
[ 2.051849] omap_target: cpu 0 not ready to go to 1008000 (inits=1
vs online=2)
This is expected as well because CPU1 has not really offline yet. And
the code is doing right thing.
... snip..
...boots up to busybox shell..
/ # head /sys/devices/system/cpu/cpu1/online /sys/devices/system/cpu/cpu0/online
==> /sys/devices/system/cpu/cpu1/online<==
1
==> /sys/devices/system/cpu/cpu0/online<==
1
/ # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
300000 600000 800000 1008000
/ # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
1008000
/ # echo -n "300000">/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
[ 130.257385] omap_target: cpu 0 not ready to go to 300000 (inits=1
vs online=2)
/ # echo -n "0"> /sys/devices/system/cpu/cpu1/online
[ 144.749877] CPU1: shutdown
/ # head /sys/devices/system/cpu/cpu1/online /sys/devices/system/cpu/cpu0/online
==> /sys/devices/system/cpu/cpu1/online<==
0
==> /sys/devices/system/cpu/cpu0/online<==
1
/ # echo -n "350000"> /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
[ 165.881927] omap_target: cpu 0 ready to go to 350000 (inits=1 vs online=1)
[ 165.889526] cpufreq-omap: transition: 1008000 --> 0
/ #
/ # echo -n "1"> /sys/devices/system/cpu/cpu1/online
[ 176.469360] CPU1: Booted secondary processor
[ 176.469421] CPU1: Unknown IPI message 0x1
[ 176.475280] Switched to NOHz mode on CPU #1
[ 176.600891] omap_cpu_init: cpu 1 cpus_initialized = 2 online=2
[ 176.620178] omap_cpu_exit: cpu 1 cpus_initialized = 1 online=2
[ 176.626373] omap_target: cpu 0 not ready to go to 350000 (inits=1
vs online=2)
All the logs look normal to me. There is nothing wrong here.
regards
Santosh
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