src/patches/suse-2.6.27.31/patches.fixes/cpufreq_ondemand_adjust_sampling_rate_limit.patch

   1 From: Thomas Renninger <trenn@suse.de>
   2 Subject: CPUFREQ: ondemand/conservative: sanitize sampling_rate restrictions
   3 References: bnc#464461
   4 Patch-Mainline: not yet
   5
   6 Limit sampling rate to transition_latency * 100 or kernel limits.
   7 If sampling_rate is tried to be set too low, set the lowest allowed value.
   8
   9 Signed-off-by: Thomas Renninger <trenn@suse.de>
  10
  11 ---
  12  Documentation/cpu-freq/governors.txt   |   14 +++++++++++++-
  13  drivers/cpufreq/cpufreq_conservative.c |   19 ++++++++++++++++---
  14  drivers/cpufreq/cpufreq_ondemand.c     |   19 +++++++++++++++----
  15  3 files changed, 44 insertions(+), 8 deletions(-)
  16
  17 Index: linux-2.6.27/Documentation/cpu-freq/governors.txt
  18 ===================================================================
  19 --- linux-2.6.27.orig/Documentation/cpu-freq/governors.txt
  20 +++ linux-2.6.27/Documentation/cpu-freq/governors.txt
  21 @@ -117,7 +117,19 @@ accessible parameters:
  22  sampling_rate: measured in uS (10^-6 seconds), this is how often you
  23  want the kernel to look at the CPU usage and to make decisions on
  24  what to do about the frequency.  Typically this is set to values of
  25 -around '10000' or more.
  26 +around '10000' or more. It's default value is (cmp. with users-guide.txt):
  27 +transition_latency * 1000
  28 +The lowest value you can set is:
  29 +transition_latency * 100 or it may get restricted to a value where it
  30 +makes not sense for the kernel anymore to poll that often which depends
  31 +on your HZ config variable (HZ=1000: max=20000us, HZ=250: max=5000).
  32 +Be aware that transition latency is in ns and sampling_rate is in us, so you
  33 +get the same sysfs value by default.
  34 +Sampling rate should always get adjusted considering the transition latency
  35 +To set the sampling rate 750 times as high as the transition latency
  36 +in the bash (as said, 1000 is default), do:
  37 +echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) \
  38 +    >ondemand/sampling_rate
  39
  40  show_sampling_rate_(min|max): the minimum and maximum sampling rates
  41  available that you may set 'sampling_rate' to.
  42 Index: linux-2.6.27/drivers/cpufreq/cpufreq_conservative.c
  43 ===================================================================
  44 --- linux-2.6.27.orig/drivers/cpufreq/cpufreq_conservative.c
  45 +++ linux-2.6.27/drivers/cpufreq/cpufreq_conservative.c
  46 @@ -54,7 +54,18 @@ static unsigned int def_sampling_rate;
  47                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
  48  #define MIN_SAMPLING_RATE                      \
  49                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
  50 +/* Above MIN_SAMPLING_RATE will vanish with its sysfs file soon
  51 + * Define the minimal settable sampling rate to the greater of:
  52 + *   - "HW transition latency" * 100 (same as default sampling / 10)
  53 + *   - MIN_STAT_SAMPLING_RATE
  54 + * To avoid that userspace shoots itself.
  55 +*/
  56 +#define MINIMUM_SAMPLING_RATE                  \
  57 +                       ((def_sampling_rate / 10) < MIN_STAT_SAMPLING_RATE \
  58 +                        ? MIN_STAT_SAMPLING_RATE : (def_sampling_rate / 10))
  59 +/* This will also vanish soon with removing sampling_rate_max */
  60  #define MAX_SAMPLING_RATE                      (500 * def_sampling_rate)
  61 +
  62  #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER   (1000)
  63  #define DEF_SAMPLING_DOWN_FACTOR               (1)
  64  #define MAX_SAMPLING_DOWN_FACTOR               (10)
  65 @@ -193,12 +204,14 @@ static ssize_t store_sampling_rate(struc
  66         ret = sscanf (buf, "%u", &input);
  67
  68         mutex_lock(&dbs_mutex);
  69 -       if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
  70 +       if (ret != 1) {
  71                 mutex_unlock(&dbs_mutex);
  72                 return -EINVAL;
  73         }
  74 -
  75 -       dbs_tuners_ins.sampling_rate = input;
  76 +       if  (input < MINIMUM_SAMPLING_RATE)
  77 +               dbs_tuners_ins.sampling_rate = MINIMUM_SAMPLING_RATE;
  78 +       else
  79 +               dbs_tuners_ins.sampling_rate = input;
  80         mutex_unlock(&dbs_mutex);
  81
  82         return count;
  83 Index: linux-2.6.27/drivers/cpufreq/cpufreq_ondemand.c
  84 ===================================================================
  85 --- linux-2.6.27.orig/drivers/cpufreq/cpufreq_ondemand.c
  86 +++ linux-2.6.27/drivers/cpufreq/cpufreq_ondemand.c
  87 @@ -45,6 +45,16 @@ static unsigned int def_sampling_rate;
  88                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
  89  #define MIN_SAMPLING_RATE                      \
  90                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
  91 +/* Above MIN_SAMPLING_RATE will vanish with its sysfs file soon
  92 + * Define the minimal settable sampling rate to the greater of:
  93 + *   - "HW transition latency" * 100 (same as default sampling / 10)
  94 + *   - MIN_STAT_SAMPLING_RATE
  95 + * To avoid that userspace shoots itself.
  96 +*/
  97 +#define MINIMUM_SAMPLING_RATE                  \
  98 +                       ((def_sampling_rate / 10) < MIN_STAT_SAMPLING_RATE \
  99 +                        ? MIN_STAT_SAMPLING_RATE : (def_sampling_rate / 10))
 100 +/* This will also vanish soon with removing sampling_rate_max */
 101  #define MAX_SAMPLING_RATE                      (500 * def_sampling_rate)
 102  #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER   (1000)
 103  #define TRANSITION_LATENCY_LIMIT               (10 * 1000 * 1000)
 104 @@ -219,13 +229,14 @@ static ssize_t store_sampling_rate(struc
 105         ret = sscanf(buf, "%u", &input);
 106
 107         mutex_lock(&dbs_mutex);
 108 -       if (ret != 1 || input > MAX_SAMPLING_RATE
 109 -                    || input < MIN_SAMPLING_RATE) {
 110 +       if (ret != 1) {
 111                 mutex_unlock(&dbs_mutex);
 112                 return -EINVAL;
 113         }
 114 -
 115 -       dbs_tuners_ins.sampling_rate = input;
 116 +       if  (input < MINIMUM_SAMPLING_RATE)
 117 +               dbs_tuners_ins.sampling_rate = MINIMUM_SAMPLING_RATE;
 118 +       else
 119 +               dbs_tuners_ins.sampling_rate = input;
 120         mutex_unlock(&dbs_mutex);
 121
 122         return count;