Re: 2.6.16-mm1 grub oddness

From: Mike Galbraith
Date: Sun Mar 26 2006 - 12:03:12 EST

On Sun, 2006-03-26 at 11:10 +0200, Mike Galbraith wrote:
> On Sat, 2006-03-25 at 13:44 +0100, Mike Galbraith wrote:
> > On Sat, 2006-03-25 at 06:14 +0100, Mike Galbraith wrote:
> > > On Fri, 2006-03-24 at 20:53 -0800, Andrew Morton wrote:
> > > >
> > > > Did you try disabling fbdev?
> > > >
> > >
> > > No, but I will.
> >
> > No dice, I just had another dead reboot. Nobody else seems to be seeing
> > this, so maybe my box is going south. A single bit error the other day,
> > and now this. Maybe it's not the kernel, just a coincidence that I've
> > only seen it with 2.6.16-mm1. Maybe I've got dust crawling into memory
> > sockets or whatnot. Memtest86 time.
>
> It's apparently not my hardware btw. If I find out what it is that's
> causing this, I'll holler.

The tentative winner for my reboot (and boot) problems appears to be
frequency scaling changes between 2.6.16-rc6-mm2, which worked fine,
and 2.6.16-mm1. Disabling frequency scaling appears to fix my troubles.
Caveat emptor: intermittent.

(Difficult for me to believe that having this compiled in could do a
number on my p4. Reverting the hotplug thingie gave me suspend back and
nothing more [as expected]. Color me befuddled.)

diff -urN linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
--- linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c 2006-03-26 12:13:21.000000000 +0200
+++ linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c 2006-03-23 14:58:44.000000000 +0100
@@ -225,9 +225,11 @@
freqs.old = data->freq_table[cur_state].frequency;
freqs.new = data->freq_table[next_state].frequency;

-#ifdef CONFIG_SMP
+#ifdef CONFIG_HOTPLUG_CPU
/* cpufreq holds the hotplug lock, so we are safe from here on */
cpus_and(online_policy_cpus, cpu_online_map, policy->cpus);
+#else
+ online_policy_cpus = policy->cpus;
#endif

for_each_cpu_mask(j, online_policy_cpus) {
diff -urN linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/powernow-k8.c linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/powernow-k8.c
--- linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/powernow-k8.c 2006-03-26 12:13:21.000000000 +0200
+++ linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/powernow-k8.c 2006-03-23 14:58:44.000000000 +0100
@@ -55,7 +55,7 @@
static struct powernow_k8_data *powernow_data[NR_CPUS];

#ifndef CONFIG_SMP
-static cpumask_t cpu_core_map[1];
+static cpumask_t cpu_core_map[1] = { CPU_MASK_ALL };
#endif

/* Return a frequency in MHz, given an input fid */
@@ -977,7 +977,7 @@
{
struct powernow_k8_data *data;
cpumask_t oldmask = CPU_MASK_ALL;
- int rc;
+ int rc, i;

if (!cpu_online(pol->cpu))
return -ENODEV;
@@ -1063,7 +1063,8 @@
printk("cpu_init done, current fid 0x%x, vid 0x%x\n",
data->currfid, data->currvid);

- powernow_data[pol->cpu] = data;
+ for_each_cpu_mask(i, cpu_core_map[pol->cpu])
+ powernow_data[i] = data;

return 0;

diff -urN linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/powernow-k8.h linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/powernow-k8.h
--- linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/powernow-k8.h 2006-03-26 12:13:21.000000000 +0200
+++ linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/powernow-k8.h 2006-03-23 14:58:44.000000000 +0100
@@ -182,10 +182,6 @@

static void powernow_k8_acpi_pst_values(struct powernow_k8_data *data, unsigned int index);

-#ifndef for_each_cpu_mask
-#define for_each_cpu_mask(i,mask) for (i=0;i<1;i++)
-#endif
-
#ifdef CONFIG_SMP
static inline void define_siblings(int cpu, cpumask_t cpu_sharedcore_mask[])
{
diff -urN linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
--- linux-2.6.16-rc6-mm2/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c 2006-03-26 12:13:21.000000000 +0200
+++ linux-2.6.16-mm1/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c 2006-03-23 14:58:44.000000000 +0100
@@ -652,9 +652,11 @@
return -EINVAL;
}

-#ifdef CONFIG_SMP
+#ifdef CONFIG_HOTPLUG_CPU
/* cpufreq holds the hotplug lock, so we are safe from here on */
cpus_and(online_policy_cpus, cpu_online_map, policy->cpus);
+#else
+ online_policy_cpus = policy->cpus;
#endif

saved_mask = current->cpus_allowed;
diff -urN linux-2.6.16-rc6-mm2/drivers/cpufreq/cpufreq_conservative.c linux-2.6.16-mm1/drivers/cpufreq/cpufreq_conservative.c
--- linux-2.6.16-rc6-mm2/drivers/cpufreq/cpufreq_conservative.c 2006-03-26 12:13:02.000000000 +0200
+++ linux-2.6.16-mm1/drivers/cpufreq/cpufreq_conservative.c 2006-03-23 14:58:45.000000000 +0100
@@ -35,12 +35,7 @@
*/

#define DEF_FREQUENCY_UP_THRESHOLD (80)
-#define MIN_FREQUENCY_UP_THRESHOLD (0)
-#define MAX_FREQUENCY_UP_THRESHOLD (100)
-
#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
-#define MIN_FREQUENCY_DOWN_THRESHOLD (0)
-#define MAX_FREQUENCY_DOWN_THRESHOLD (100)

/*
* The polling frequency of this governor depends on the capability of
@@ -53,10 +48,14 @@
* All times here are in uS.
*/
static unsigned int def_sampling_rate;
-#define MIN_SAMPLING_RATE (def_sampling_rate / 2)
+#define MIN_SAMPLING_RATE_RATIO (2)
+/* for correct statistics, we need at least 10 ticks between each measure */
+#define MIN_STAT_SAMPLING_RATE (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
+#define MIN_SAMPLING_RATE (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
-#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (100000)
-#define DEF_SAMPLING_DOWN_FACTOR (5)
+#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
+#define DEF_SAMPLING_DOWN_FACTOR (1)
+#define MAX_SAMPLING_DOWN_FACTOR (10)
#define TRANSITION_LATENCY_LIMIT (10 * 1000)

static void do_dbs_timer(void *data);
@@ -66,6 +65,8 @@
unsigned int prev_cpu_idle_up;
unsigned int prev_cpu_idle_down;
unsigned int enable;
+ unsigned int down_skip;
+ unsigned int requested_freq;
};
static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);

@@ -136,7 +137,7 @@
unsigned int input;
int ret;
ret = sscanf (buf, "%u", &input);
- if (ret != 1 )
+ if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
return -EINVAL;

mutex_lock(&dbs_mutex);
@@ -173,8 +174,7 @@
ret = sscanf (buf, "%u", &input);

mutex_lock(&dbs_mutex);
- if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
- input < MIN_FREQUENCY_UP_THRESHOLD ||
+ if (ret != 1 || input > 100 || input < 0 ||
input <= dbs_tuners_ins.down_threshold) {
mutex_unlock(&dbs_mutex);
return -EINVAL;
@@ -194,8 +194,7 @@
ret = sscanf (buf, "%u", &input);

mutex_lock(&dbs_mutex);
- if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD ||
- input < MIN_FREQUENCY_DOWN_THRESHOLD ||
+ if (ret != 1 || input > 100 || input < 0 ||
input >= dbs_tuners_ins.up_threshold) {
mutex_unlock(&dbs_mutex);
return -EINVAL;
@@ -297,31 +296,17 @@
static void dbs_check_cpu(int cpu)
{
unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
+ unsigned int tmp_idle_ticks, total_idle_ticks;
unsigned int freq_step;
unsigned int freq_down_sampling_rate;
- static int down_skip[NR_CPUS];
- static int requested_freq[NR_CPUS];
- static unsigned short init_flag = 0;
- struct cpu_dbs_info_s *this_dbs_info;
- struct cpu_dbs_info_s *dbs_info;
-
+ struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
struct cpufreq_policy *policy;
- unsigned int j;

- this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
if (!this_dbs_info->enable)
return;

policy = this_dbs_info->cur_policy;

- if ( init_flag == 0 ) {
- for_each_online_cpu(j) {
- dbs_info = &per_cpu(cpu_dbs_info, j);
- requested_freq[j] = dbs_info->cur_policy->cur;
- }
- init_flag = 1;
- }
-
/*
* The default safe range is 20% to 80%
* Every sampling_rate, we check
@@ -337,39 +322,29 @@
*/

/* Check for frequency increase */
-
idle_ticks = UINT_MAX;
- for_each_cpu_mask(j, policy->cpus) {
- unsigned int tmp_idle_ticks, total_idle_ticks;
- struct cpu_dbs_info_s *j_dbs_info;

- j_dbs_info = &per_cpu(cpu_dbs_info, j);
- /* Check for frequency increase */
- total_idle_ticks = get_cpu_idle_time(j);
- tmp_idle_ticks = total_idle_ticks -
- j_dbs_info->prev_cpu_idle_up;
- j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
+ /* Check for frequency increase */
+ total_idle_ticks = get_cpu_idle_time(cpu);
+ tmp_idle_ticks = total_idle_ticks -
+ this_dbs_info->prev_cpu_idle_up;
+ this_dbs_info->prev_cpu_idle_up = total_idle_ticks;

- if (tmp_idle_ticks < idle_ticks)
- idle_ticks = tmp_idle_ticks;
- }
+ if (tmp_idle_ticks < idle_ticks)
+ idle_ticks = tmp_idle_ticks;

/* Scale idle ticks by 100 and compare with up and down ticks */
idle_ticks *= 100;
up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
- usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+ usecs_to_jiffies(dbs_tuners_ins.sampling_rate);

if (idle_ticks < up_idle_ticks) {
- down_skip[cpu] = 0;
- for_each_cpu_mask(j, policy->cpus) {
- struct cpu_dbs_info_s *j_dbs_info;
+ this_dbs_info->down_skip = 0;
+ this_dbs_info->prev_cpu_idle_down =
+ this_dbs_info->prev_cpu_idle_up;

- j_dbs_info = &per_cpu(cpu_dbs_info, j);
- j_dbs_info->prev_cpu_idle_down =
- j_dbs_info->prev_cpu_idle_up;
- }
/* if we are already at full speed then break out early */
- if (requested_freq[cpu] == policy->max)
+ if (this_dbs_info->requested_freq == policy->max)
return;

freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
@@ -378,49 +353,45 @@
if (unlikely(freq_step == 0))
freq_step = 5;

- requested_freq[cpu] += freq_step;
- if (requested_freq[cpu] > policy->max)
- requested_freq[cpu] = policy->max;
+ this_dbs_info->requested_freq += freq_step;
+ if (this_dbs_info->requested_freq > policy->max)
+ this_dbs_info->requested_freq = policy->max;

- __cpufreq_driver_target(policy, requested_freq[cpu],
+ __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
CPUFREQ_RELATION_H);
return;
}

/* Check for frequency decrease */
- down_skip[cpu]++;
- if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
+ this_dbs_info->down_skip++;
+ if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor)
return;

- idle_ticks = UINT_MAX;
- for_each_cpu_mask(j, policy->cpus) {
- unsigned int tmp_idle_ticks, total_idle_ticks;
- struct cpu_dbs_info_s *j_dbs_info;
-
- j_dbs_info = &per_cpu(cpu_dbs_info, j);
- total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
- tmp_idle_ticks = total_idle_ticks -
- j_dbs_info->prev_cpu_idle_down;
- j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
+ /* Check for frequency decrease */
+ total_idle_ticks = this_dbs_info->prev_cpu_idle_up;
+ tmp_idle_ticks = total_idle_ticks -
+ this_dbs_info->prev_cpu_idle_down;
+ this_dbs_info->prev_cpu_idle_down = total_idle_ticks;

- if (tmp_idle_ticks < idle_ticks)
- idle_ticks = tmp_idle_ticks;
- }
+ if (tmp_idle_ticks < idle_ticks)
+ idle_ticks = tmp_idle_ticks;

/* Scale idle ticks by 100 and compare with up and down ticks */
idle_ticks *= 100;
- down_skip[cpu] = 0;
+ this_dbs_info->down_skip = 0;

freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
dbs_tuners_ins.sampling_down_factor;
down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
- usecs_to_jiffies(freq_down_sampling_rate);
+ usecs_to_jiffies(freq_down_sampling_rate);

if (idle_ticks > down_idle_ticks) {
- /* if we are already at the lowest speed then break out early
+ /*
+ * if we are already at the lowest speed then break out early
* or if we 'cannot' reduce the speed as the user might want
- * freq_step to be zero */
- if (requested_freq[cpu] == policy->min
+ * freq_step to be zero
+ */
+ if (this_dbs_info->requested_freq == policy->min
|| dbs_tuners_ins.freq_step == 0)
return;

@@ -430,13 +401,12 @@
if (unlikely(freq_step == 0))
freq_step = 5;

- requested_freq[cpu] -= freq_step;
- if (requested_freq[cpu] < policy->min)
- requested_freq[cpu] = policy->min;
+ this_dbs_info->requested_freq -= freq_step;
+ if (this_dbs_info->requested_freq < policy->min)
+ this_dbs_info->requested_freq = policy->min;

- __cpufreq_driver_target(policy,
- requested_freq[cpu],
- CPUFREQ_RELATION_H);
+ __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
+ CPUFREQ_RELATION_H);
return;
}
}
@@ -493,11 +463,13 @@
j_dbs_info = &per_cpu(cpu_dbs_info, j);
j_dbs_info->cur_policy = policy;

- j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
+ j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(cpu);
j_dbs_info->prev_cpu_idle_down
= j_dbs_info->prev_cpu_idle_up;
}
this_dbs_info->enable = 1;
+ this_dbs_info->down_skip = 0;
+ this_dbs_info->requested_freq = policy->cur;
sysfs_create_group(&policy->kobj, &dbs_attr_group);
dbs_enable++;
/*
@@ -507,13 +479,16 @@
if (dbs_enable == 1) {
unsigned int latency;
/* policy latency is in nS. Convert it to uS first */
+ latency = policy->cpuinfo.transition_latency / 1000;
+ if (latency == 0)
+ latency = 1;

- latency = policy->cpuinfo.transition_latency;
- if (latency < 1000)
- latency = 1000;
-
- def_sampling_rate = (latency / 1000) *
+ def_sampling_rate = 10 * latency *
DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
+
+ if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
+ def_sampling_rate = MIN_STAT_SAMPLING_RATE;
+
dbs_tuners_ins.sampling_rate = def_sampling_rate;
dbs_tuners_ins.ignore_nice = 0;
dbs_tuners_ins.freq_step = 5;


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