vcs.maemo.org Git - kernel-bfs/blob - kernel-bfs-2.6.28/debian/patches/bfs-357-to-360.patch

   1 Don't unnecessarily preempt for a task on the wrong CPU.
   2
   3 Cope with worker threads trying to wake themselves up due to shifting CPUs on
   4 suspend by reactivating it, instead of hitting the BUG_ON
   5
   6 Wrap timer jiffies at 10 seconds instead of 5 minutes since 32 bit load
   7 averages don't work until the first timer wrap.
   8
   9 Remove the last_task logic as it wasn't providing any significant performance
  10 advantage.
  11
  12 Change the locality logic to try to reschedule on the exact same logical core
  13 instead of assuming scheduling on a sibling core or sibling thread is
  14 equivalent. This allows CPUs with a "turbo" mode (such as i7) to use that more
  15 often by using one CPU more than spreading out, and allows ondemand cpu
  16 frequency scaling to ramp up more easily when a task stays on the same CPU. It
  17 increases throughput on threaded CPUs when lightly loaded, and may offer both
  18 performance and power saving advantages on all SMP topologies with cpu
  19 frequency scaling.
  20
  21 -ck
  22
  23 ---
  24  include/linux/jiffies.h |    2 -
  25  include/linux/sched.h   |    2 -
  26  kernel/sched_bfs.c      |   89 ++++++++++++++++++++++--------------------------
  27  3 files changed, 43 insertions(+), 50 deletions(-)
  28
  29 Index: linux-2.6.28/include/linux/jiffies.h
  30 ===================================================================
  31 --- linux-2.6.28.orig/include/linux/jiffies.h   2010-12-14 22:13:10.975304692 +1100
  32 +++ linux-2.6.28/include/linux/jiffies.h        2010-12-14 22:14:03.530569735 +1100
  33 @@ -154,7 +154,7 @@ static inline u64 get_jiffies_64(void)
  34   * Have the 32 bit jiffies value wrap 5 minutes after boot
  35   * so jiffies wrap bugs show up earlier.
  36   */
  37 -#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))
  38 +#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-10*HZ))
  39
  40  /*
  41   * Change timeval to jiffies, trying to avoid the
  42 Index: linux-2.6.28/include/linux/sched.h
  43 ===================================================================
  44 --- linux-2.6.28.orig/include/linux/sched.h     2010-12-14 22:13:10.965304640 +1100
  45 +++ linux-2.6.28/include/linux/sched.h  2010-12-14 22:14:03.524569704 +1100
  46 @@ -1426,7 +1426,7 @@ static inline void tsk_cpus_current(stru
  47
  48  static inline void print_scheduler_version(void)
  49  {
  50 -       printk(KERN_INFO"BFS CPU scheduler v0.357 by Con Kolivas.\n");
  51 +       printk(KERN_INFO"BFS CPU scheduler v0.360 by Con Kolivas.\n");
  52  }
  53
  54  static inline int iso_task(struct task_struct *p)
  55 Index: linux-2.6.28/kernel/sched_bfs.c
  56 ===================================================================
  57 --- linux-2.6.28.orig/kernel/sched_bfs.c        2010-12-14 22:13:10.983304734 +1100
  58 +++ linux-2.6.28/kernel/sched_bfs.c     2010-12-14 22:14:54.061814177 +1100
  59 @@ -204,7 +204,6 @@ struct rq {
  60  #ifdef CONFIG_NO_HZ
  61         unsigned char in_nohz_recently;
  62  #endif
  63 -       struct task_struct *last_task;
  64  #endif
  65
  66         struct task_struct *curr, *idle;
  67 @@ -733,19 +732,12 @@ static int suitable_idle_cpus(struct tas
  68
  69  static void resched_task(struct task_struct *p);
  70
  71 -/*
  72 - * last_task stores the last non-idle task scheduled on the local rq for
  73 - * cache warmth testing.
  74 - */
  75 -static inline void set_last_task(struct rq *rq, struct task_struct *p)
  76 -{
  77 -       rq->last_task = p;
  78 -}
  79 -
  80 -#define CPUIDLE_CACHE_BUSY     (1)
  81 -#define CPUIDLE_DIFF_CPU       (2)
  82 -#define CPUIDLE_THREAD_BUSY    (4)
  83 -#define CPUIDLE_DIFF_NODE      (8)
  84 +#define CPUIDLE_DIFF_THREAD    (1)
  85 +#define CPUIDLE_DIFF_CORE      (2)
  86 +#define CPUIDLE_CACHE_BUSY     (4)
  87 +#define CPUIDLE_DIFF_CPU       (8)
  88 +#define CPUIDLE_THREAD_BUSY    (16)
  89 +#define CPUIDLE_DIFF_NODE      (32)
  90
  91  /*
  92   * The best idle CPU is chosen according to the CPUIDLE ranking above where the
  93 @@ -798,27 +790,28 @@ static void resched_best_idle(struct tas
  94                 }
  95                 tmp_rq = cpu_rq(cpu_tmp);
  96
  97 -               if (rq->cpu_locality[cpu_tmp]) {
  98 -                       /* Check rq->last_task hasn't been dereferenced */
  99 -                       if (rq->last_task && p != rq->last_task) {
 100  #ifdef CONFIG_NUMA
 101 -                               if (rq->cpu_locality[cpu_tmp] > 1)
 102 -                                       ranking |= CPUIDLE_DIFF_NODE;
 103 +               if (rq->cpu_locality[cpu_tmp] > 3)
 104 +                       ranking |= CPUIDLE_DIFF_NODE;
 105 +               else
 106  #endif
 107 -                               ranking |= CPUIDLE_DIFF_CPU;
 108 -                       }
 109 -               }
 110 +               if (rq->cpu_locality[cpu_tmp] > 2)
 111 +                       ranking |= CPUIDLE_DIFF_CPU;
 112  #ifdef CONFIG_SCHED_MC
 113 +               if (rq->cpu_locality[cpu_tmp] == 2)
 114 +                       ranking |= CPUIDLE_DIFF_CORE;
 115                 if (!(tmp_rq->cache_idle(cpu_tmp)))
 116                         ranking |= CPUIDLE_CACHE_BUSY;
 117  #endif
 118  #ifdef CONFIG_SCHED_SMT
 119 +               if (rq->cpu_locality[cpu_tmp] == 1)
 120 +                       ranking |= CPUIDLE_DIFF_THREAD;
 121                 if (!(tmp_rq->siblings_idle(cpu_tmp)))
 122                         ranking |= CPUIDLE_THREAD_BUSY;
 123  #endif
 124                 if (ranking < best_ranking) {
 125                         best_cpu = cpu_tmp;
 126 -                       if (ranking <= 1)
 127 +                       if (ranking == 0)
 128                                 break;
 129                         best_ranking = ranking;
 130                 }
 131 @@ -835,11 +828,11 @@ static inline void resched_suitable_idle
 132
 133  /*
 134   * The cpu cache locality difference between CPUs is used to determine how far
 135 - * to offset the virtual deadline. "One" difference in locality means that one
 136 + * to offset the virtual deadline. <2 difference in locality means that one
 137   * timeslice difference is allowed longer for the cpu local tasks. This is
 138   * enough in the common case when tasks are up to 2* number of CPUs to keep
 139   * tasks within their shared cache CPUs only. CPUs on different nodes or not
 140 - * even in this domain (NUMA) have "3" difference, allowing 4 times longer
 141 + * even in this domain (NUMA) have "4" difference, allowing 4 times longer
 142   * deadlines before being taken onto another cpu, allowing for 2* the double
 143   * seen by separate CPUs above.
 144   * Simple summary: Virtual deadlines are equal on shared cache CPUs, double
 145 @@ -848,12 +841,11 @@ static inline void resched_suitable_idle
 146  static inline int
 147  cache_distance(struct rq *task_rq, struct rq *rq, struct task_struct *p)
 148  {
 149 -       /* Check rq->last_task hasn't been dereferenced */
 150 -       if (likely(rq->last_task)) {
 151 -               if (rq->last_task == p)
 152 -                       return 0;
 153 -       }
 154 -       return rq->cpu_locality[cpu_of(task_rq)] * task_timeslice(p);
 155 +       int locality = rq->cpu_locality[cpu_of(task_rq)] - 2;
 156 +
 157 +       if (locality > 0)
 158 +               return task_timeslice(p) << locality;
 159 +       return 0;
 160  }
 161  #else /* CONFIG_SMP */
 162  static inline void inc_qnr(void)
 163 @@ -892,10 +884,6 @@ cache_distance(struct rq *task_rq, struc
 164  {
 165         return 0;
 166  }
 167 -
 168 -static inline void set_last_task(struct rq *rq, struct task_struct *p)
 169 -{
 170 -}
 171  #endif /* CONFIG_SMP */
 172
 173  /*
 174 @@ -1287,10 +1275,10 @@ static void try_preempt(struct task_stru
 175                 return;
 176         }
 177
 178 -       if (online_cpus(p))
 179 +       if (likely(online_cpus(p)))
 180                 cpus_and(tmp, cpu_online_map, p->cpus_allowed);
 181         else
 182 -               (cpumask_copy(&tmp, &cpu_online_map));
 183 +               return;
 184
 185         latest_deadline = 0;
 186         highest_prio = -1;
 187 @@ -2597,7 +2585,7 @@ need_resched_nonpreemptible:
 188                 prev->last_ran = rq->clock;
 189
 190                 /* Task changed affinity off this CPU */
 191 -               if (needs_other_cpu(prev, cpu))
 192 +               if (unlikely(!cpu_isset(cpu, prev->cpus_allowed)))
 193                         resched_suitable_idle(prev);
 194                 else if (!deactivate) {
 195                         if (!queued_notrunning()) {
 196 @@ -2639,8 +2627,6 @@ need_resched_nonpreemptible:
 197         if (likely(prev != next)) {
 198                 sched_info_switch(prev, next);
 199
 200 -               if (prev != idle)
 201 -                       set_last_task(rq, prev);
 202                 set_rq_task(rq, next);
 203                 grq.nr_switches++;
 204                 prev->oncpu = 0;
 205 @@ -6054,10 +6040,12 @@ void __init sched_init_smp(void)
 206                                         cpu_set(other_cpu, rq->cache_siblings);
 207                         }
 208  #endif
 209 -                       if (sd->level <= SD_LV_MC)
 210 -                               locality = 0;
 211 -                       else if (sd->level <= SD_LV_NODE)
 212 +                       if (sd->level <= SD_LV_SIBLING)
 213                                 locality = 1;
 214 +                       else if (sd->level <= SD_LV_MC)
 215 +                               locality = 2;
 216 +                       else if (sd->level <= SD_LV_NODE)
 217 +                               locality = 3;
 218                         else
 219                                 continue;
 220
 221 @@ -6160,7 +6148,7 @@ void __init sched_init(void)
 222                         if (i == j)
 223                                 rq->cpu_locality[j] = 0;
 224                         else
 225 -                               rq->cpu_locality[j] = 3;
 226 +                               rq->cpu_locality[j] = 4;
 227                 }
 228         }
 229  #endif