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/*
* Cell Broadband Engine OProfile Support
*
* (C) Copyright IBM Corporation 2006
*
* Authors: Maynard Johnson <maynardj@us.ibm.com>
* Carl Love <carll@us.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/hrtimer.h>
#include <linux/smp.h>
#include <linux/slab.h>
#include <asm/cell-pmu.h>
#include "pr_util.h"
#define TRACE_ARRAY_SIZE 1024
#define SCALE_SHIFT 14
static u32 *samples;
static int spu_prof_running;
static unsigned int profiling_interval;
#define NUM_SPU_BITS_TRBUF 16
#define SPUS_PER_TB_ENTRY 4
#define SPUS_PER_NODE 8
#define SPU_PC_MASK 0xFFFF
static DEFINE_SPINLOCK(sample_array_lock);
unsigned long sample_array_lock_flags;
void set_spu_profiling_frequency(unsigned int freq_khz, unsigned int cycles_reset)
{
unsigned long ns_per_cyc;
if (!freq_khz)
freq_khz = ppc_proc_freq/1000;
/* To calculate a timeout in nanoseconds, the basic
* formula is ns = cycles_reset * (NSEC_PER_SEC / cpu frequency).
* To avoid floating point math, we use the scale math
* technique as described in linux/jiffies.h. We use
* a scale factor of SCALE_SHIFT, which provides 4 decimal places
* of precision. This is close enough for the purpose at hand.
*
* The value of the timeout should be small enough that the hw
* trace buffer will not get more then about 1/3 full for the
* maximum user specified (the LFSR value) hw sampling frequency.
* This is to ensure the trace buffer will never fill even if the
* kernel thread scheduling varies under a heavy system load.
*/
ns_per_cyc = (USEC_PER_SEC << SCALE_SHIFT)/freq_khz;
profiling_interval = (ns_per_cyc * cycles_reset) >> SCALE_SHIFT;
}
/*
* Extract SPU PC from trace buffer entry
*/
static void spu_pc_extract(int cpu, int entry)
{
/* the trace buffer is 128 bits */
u64 trace_buffer[2];
u64 spu_mask;
int spu;
spu_mask = SPU_PC_MASK;
/* Each SPU PC is 16 bits; hence, four spus in each of
* the two 64-bit buffer entries that make up the
* 128-bit trace_buffer entry. Process two 64-bit values
* simultaneously.
* trace[0] SPU PC contents are: 0 1 2 3
* trace[1] SPU PC contents are: 4 5 6 7
*/
cbe_read_trace_buffer(cpu, trace_buffer);
for (spu = SPUS_PER_TB_ENTRY-1; spu >= 0; spu--) {
/* spu PC trace entry is upper 16 bits of the
* 18 bit SPU program counter
*/
samples[spu * TRACE_ARRAY_SIZE + entry]
= (spu_mask & trace_buffer[0]) << 2;
samples[(spu + SPUS_PER_TB_ENTRY) * TRACE_ARRAY_SIZE + entry]
= (spu_mask & trace_buffer[1]) << 2;
trace_buffer[0] = trace_buffer[0] >> NUM_SPU_BITS_TRBUF;
trace_buffer[1] = trace_buffer[1] >> NUM_SPU_BITS_TRBUF;
}
}
static int cell_spu_pc_collection(int cpu)
{
u32 trace_addr;
int entry;
/* process the collected SPU PC for the node */
entry = 0;
trace_addr = cbe_read_pm(cpu, trace_address);
while (!(trace_addr & CBE_PM_TRACE_BUF_EMPTY)) {
/* there is data in the trace buffer to process */
spu_pc_extract(cpu, entry);
entry++;
if (entry >= TRACE_ARRAY_SIZE)
/* spu_samples is full */
break;
trace_addr = cbe_read_pm(cpu, trace_address);
}
return entry;
}
static enum hrtimer_restart profile_spus(struct hrtimer *timer)
{
ktime_t kt;
int cpu, node, k, num_samples, spu_num;
if (!spu_prof_running)
goto stop;
for_each_online_cpu(cpu) {
if (cbe_get_hw_thread_id(cpu))
continue;
node = cbe_cpu_to_node(cpu);
/* There should only be one kernel thread at a time processing
* the samples. In the very unlikely case that the processing
* is taking a very long time and multiple kernel threads are
* started to process the samples. Make sure only one kernel
* thread is working on the samples array at a time. The
* sample array must be loaded and then processed for a given
* cpu. The sample array is not per cpu.
*/
spin_lock_irqsave(&sample_array_lock,
sample_array_lock_flags);
num_samples = cell_spu_pc_collection(cpu);
if (num_samples == 0) {
spin_unlock_irqrestore(&sample_array_lock,
sample_array_lock_flags);
continue;
}
for (k = 0; k < SPUS_PER_NODE; k++) {
spu_num = k + (node * SPUS_PER_NODE);
spu_sync_buffer(spu_num,
samples + (k * TRACE_ARRAY_SIZE),
num_samples);
}
spin_unlock_irqrestore(&sample_array_lock,
sample_array_lock_flags);
}
smp_wmb(); /* insure spu event buffer updates are written */
/* don't want events intermingled... */
kt = ktime_set(0, profiling_interval);
if (!spu_prof_running)
goto stop;
hrtimer_forward(timer, timer->base->get_time(), kt);
return HRTIMER_RESTART;
stop:
printk(KERN_INFO "SPU_PROF: spu-prof timer ending\n");
return HRTIMER_NORESTART;
}
static struct hrtimer timer;
/*
* Entry point for SPU profiling.
* NOTE: SPU profiling is done system-wide, not per-CPU.
*
* cycles_reset is the count value specified by the user when
* setting up OProfile to count SPU_CYCLES.
*/
int start_spu_profiling(unsigned int cycles_reset)
{
ktime_t kt;
pr_debug("timer resolution: %lu\n", TICK_NSEC);
kt = ktime_set(0, profiling_interval);
hrtimer_init(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer_set_expires(&timer, kt);
timer.function = profile_spus;
/* Allocate arrays for collecting SPU PC samples */
samples = kzalloc(SPUS_PER_NODE *
TRACE_ARRAY_SIZE * sizeof(u32), GFP_KERNEL);
if (!samples)
return -ENOMEM;
spu_prof_running = 1;
hrtimer_start(&timer, kt, HRTIMER_MODE_REL);
return 0;
}
void stop_spu_profiling(void)
{
spu_prof_running = 0;
hrtimer_cancel(&timer);
kfree(samples);
pr_debug("SPU_PROF: stop_spu_profiling issued\n");
}
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