arch/powerpc/oprofile/cell/spu_profiler.c

   1 /*
   2  * Cell Broadband Engine OProfile Support
   3  *
   4  * (C) Copyright IBM Corporation 2006
   5  *
   6  * Authors: Maynard Johnson <maynardj@us.ibm.com>
   7  *          Carl Love <carll@us.ibm.com>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation; either version
  12  * 2 of the License, or (at your option) any later version.
  13  */
  14
  15 #include <linux/hrtimer.h>
  16 #include <linux/smp.h>
  17 #include <linux/slab.h>
  18 #include <asm/cell-pmu.h>
  19 #include <asm/time.h>
  20 #include "pr_util.h"
  21
  22 #define SCALE_SHIFT 14
  23
  24 static u32 *samples;
  25
  26 /* spu_prof_running is a flag used to indicate if spu profiling is enabled
  27  * or not.  It is set by the routines start_spu_profiling_cycles() and
  28  * start_spu_profiling_events().  The flag is cleared by the routines
  29  * stop_spu_profiling_cycles() and stop_spu_profiling_events().  These
  30  * routines are called via global_start() and global_stop() which are called in
  31  * op_powerpc_start() and op_powerpc_stop().  These routines are called once
  32  * per system as a result of the user starting/stopping oprofile.  Hence, only
  33  * one CPU per user at a time will be changing  the value of spu_prof_running.
  34  * In general, OProfile does not protect against multiple users trying to run
  35  * OProfile at a time.
  36  */
  37 int spu_prof_running;
  38 static unsigned int profiling_interval;
  39
  40 #define NUM_SPU_BITS_TRBUF 16
  41 #define SPUS_PER_TB_ENTRY   4
  42
  43 #define SPU_PC_MASK          0xFFFF
  44
  45 DEFINE_SPINLOCK(oprof_spu_smpl_arry_lck);
  46 static unsigned long oprof_spu_smpl_arry_lck_flags;
  47
  48 void set_spu_profiling_frequency(unsigned int freq_khz, unsigned int cycles_reset)
  49 {
  50         unsigned long ns_per_cyc;
  51
  52         if (!freq_khz)
  53                 freq_khz = ppc_proc_freq/1000;
  54
  55         /* To calculate a timeout in nanoseconds, the basic
  56          * formula is ns = cycles_reset * (NSEC_PER_SEC / cpu frequency).
  57          * To avoid floating point math, we use the scale math
  58          * technique as described in linux/jiffies.h.  We use
  59          * a scale factor of SCALE_SHIFT, which provides 4 decimal places
  60          * of precision.  This is close enough for the purpose at hand.
  61          *
  62          * The value of the timeout should be small enough that the hw
  63          * trace buffer will not get more than about 1/3 full for the
  64          * maximum user specified (the LFSR value) hw sampling frequency.
  65          * This is to ensure the trace buffer will never fill even if the
  66          * kernel thread scheduling varies under a heavy system load.
  67          */
  68
  69         ns_per_cyc = (USEC_PER_SEC << SCALE_SHIFT)/freq_khz;
  70         profiling_interval = (ns_per_cyc * cycles_reset) >> SCALE_SHIFT;
  71
  72 }
  73
  74 /*
  75  * Extract SPU PC from trace buffer entry
  76  */
  77 static void spu_pc_extract(int cpu, int entry)
  78 {
  79         /* the trace buffer is 128 bits */
  80         u64 trace_buffer[2];
  81         u64 spu_mask;
  82         int spu;
  83
  84         spu_mask = SPU_PC_MASK;
  85
  86         /* Each SPU PC is 16 bits; hence, four spus in each of
  87          * the two 64-bit buffer entries that make up the
  88          * 128-bit trace_buffer entry.  Process two 64-bit values
  89          * simultaneously.
  90          * trace[0] SPU PC contents are: 0 1 2 3
  91          * trace[1] SPU PC contents are: 4 5 6 7
  92          */
  93
  94         cbe_read_trace_buffer(cpu, trace_buffer);
  95
  96         for (spu = SPUS_PER_TB_ENTRY-1; spu >= 0; spu--) {
  97                 /* spu PC trace entry is upper 16 bits of the
  98                  * 18 bit SPU program counter
  99                  */
 100                 samples[spu * TRACE_ARRAY_SIZE + entry]
 101                         = (spu_mask & trace_buffer[0]) << 2;
 102                 samples[(spu + SPUS_PER_TB_ENTRY) * TRACE_ARRAY_SIZE + entry]
 103                         = (spu_mask & trace_buffer[1]) << 2;
 104
 105                 trace_buffer[0] = trace_buffer[0] >> NUM_SPU_BITS_TRBUF;
 106                 trace_buffer[1] = trace_buffer[1] >> NUM_SPU_BITS_TRBUF;
 107         }
 108 }
 109
 110 static int cell_spu_pc_collection(int cpu)
 111 {
 112         u32 trace_addr;
 113         int entry;
 114
 115         /* process the collected SPU PC for the node */
 116
 117         entry = 0;
 118
 119         trace_addr = cbe_read_pm(cpu, trace_address);
 120         while (!(trace_addr & CBE_PM_TRACE_BUF_EMPTY)) {
 121                 /* there is data in the trace buffer to process */
 122                 spu_pc_extract(cpu, entry);
 123
 124                 entry++;
 125
 126                 if (entry >= TRACE_ARRAY_SIZE)
 127                         /* spu_samples is full */
 128                         break;
 129
 130                 trace_addr = cbe_read_pm(cpu, trace_address);
 131         }
 132
 133         return entry;
 134 }
 135
 136
 137 static enum hrtimer_restart profile_spus(struct hrtimer *timer)
 138 {
 139         ktime_t kt;
 140         int cpu, node, k, num_samples, spu_num;
 141
 142         if (!spu_prof_running)
 143                 goto stop;
 144
 145         for_each_online_cpu(cpu) {
 146                 if (cbe_get_hw_thread_id(cpu))
 147                         continue;
 148
 149                 node = cbe_cpu_to_node(cpu);
 150
 151                 /* There should only be one kernel thread at a time processing
 152                  * the samples.  In the very unlikely case that the processing
 153                  * is taking a very long time and multiple kernel threads are
 154                  * started to process the samples.  Make sure only one kernel
 155                  * thread is working on the samples array at a time.  The
 156                  * sample array must be loaded and then processed for a given
 157                  * cpu.  The sample array is not per cpu.
 158                  */
 159                 spin_lock_irqsave(&oprof_spu_smpl_arry_lck,
 160                                   oprof_spu_smpl_arry_lck_flags);
 161                 num_samples = cell_spu_pc_collection(cpu);
 162
 163                 if (num_samples == 0) {
 164                         spin_unlock_irqrestore(&oprof_spu_smpl_arry_lck,
 165                                                oprof_spu_smpl_arry_lck_flags);
 166                         continue;
 167                 }
 168
 169                 for (k = 0; k < SPUS_PER_NODE; k++) {
 170                         spu_num = k + (node * SPUS_PER_NODE);
 171                         spu_sync_buffer(spu_num,
 172                                         samples + (k * TRACE_ARRAY_SIZE),
 173                                         num_samples);
 174                 }
 175
 176                 spin_unlock_irqrestore(&oprof_spu_smpl_arry_lck,
 177                                        oprof_spu_smpl_arry_lck_flags);
 178
 179         }
 180         smp_wmb();      /* insure spu event buffer updates are written */
 181                         /* don't want events intermingled... */
 182
 183         kt = ktime_set(0, profiling_interval);
 184         if (!spu_prof_running)
 185                 goto stop;
 186         hrtimer_forward(timer, timer->base->get_time(), kt);
 187         return HRTIMER_RESTART;
 188
 189  stop:
 190         printk(KERN_INFO "SPU_PROF: spu-prof timer ending\n");
 191         return HRTIMER_NORESTART;
 192 }
 193
 194 static struct hrtimer timer;
 195 /*
 196  * Entry point for SPU cycle profiling.
 197  * NOTE:  SPU profiling is done system-wide, not per-CPU.
 198  *
 199  * cycles_reset is the count value specified by the user when
 200  * setting up OProfile to count SPU_CYCLES.
 201  */
 202 int start_spu_profiling_cycles(unsigned int cycles_reset)
 203 {
 204         ktime_t kt;
 205
 206         pr_debug("timer resolution: %lu\n", TICK_NSEC);
 207         kt = ktime_set(0, profiling_interval);
 208         hrtimer_init(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 209         hrtimer_set_expires(&timer, kt);
 210         timer.function = profile_spus;
 211
 212         /* Allocate arrays for collecting SPU PC samples */
 213         samples = kzalloc(SPUS_PER_NODE *
 214                           TRACE_ARRAY_SIZE * sizeof(u32), GFP_KERNEL);
 215
 216         if (!samples)
 217                 return -ENOMEM;
 218
 219         spu_prof_running = 1;
 220         hrtimer_start(&timer, kt, HRTIMER_MODE_REL);
 221         schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
 222
 223         return 0;
 224 }
 225
 226 /*
 227  * Entry point for SPU event profiling.
 228  * NOTE:  SPU profiling is done system-wide, not per-CPU.
 229  *
 230  * cycles_reset is the count value specified by the user when
 231  * setting up OProfile to count SPU_CYCLES.
 232  */
 233 void start_spu_profiling_events(void)
 234 {
 235         spu_prof_running = 1;
 236         schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
 237
 238         return;
 239 }
 240
 241 void stop_spu_profiling_cycles(void)
 242 {
 243         spu_prof_running = 0;
 244         hrtimer_cancel(&timer);
 245         kfree(samples);
 246         pr_debug("SPU_PROF: stop_spu_profiling_cycles issued\n");
 247 }
 248
 249 void stop_spu_profiling_events(void)
 250 {
 251         spu_prof_running = 0;
 252 }