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hw_breakpoint: Introduce "struct bp_cpuinfo"
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This patch simply moves all per-cpu variables into the new
single per-cpu "struct bp_cpuinfo".

To me this looks more logical and clean, but this can also
simplify the further potential changes. In particular, I do not
think this memory should be per-cpu, it is never used "locally".
After this change it is trivial to turn it into, say,
bootmem[nr_cpu_ids].

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20130620155020.GA6350@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Oleg Nesterov authored and Ingo Molnar committed Jun 20, 2013
1 parent e12cbc1 commit bde9603
Showing 1 changed file with 36 additions and 33 deletions.
69 changes: 36 additions & 33 deletions kernel/events/hw_breakpoint.c
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Original file line number Diff line number Diff line change
Expand Up @@ -46,23 +46,26 @@
#include <linux/smp.h>

#include <linux/hw_breakpoint.h>


/*
* Constraints data
*/
struct bp_cpuinfo {
/* Number of pinned cpu breakpoints in a cpu */
unsigned int cpu_pinned;
/* tsk_pinned[n] is the number of tasks having n+1 breakpoints */
unsigned int *tsk_pinned;
/* Number of non-pinned cpu/task breakpoints in a cpu */
unsigned int flexible; /* XXX: placeholder, see fetch_this_slot() */
};

/* Number of pinned cpu breakpoints in a cpu */
static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]);

/* Number of pinned task breakpoints in a cpu */
static DEFINE_PER_CPU(unsigned int *, nr_task_bp_pinned[TYPE_MAX]);

/* Number of non-pinned cpu/task breakpoints in a cpu */
static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]);

static DEFINE_PER_CPU(struct bp_cpuinfo, bp_cpuinfo[TYPE_MAX]);
static int nr_slots[TYPE_MAX];

static struct bp_cpuinfo *get_bp_info(int cpu, enum bp_type_idx type)
{
return per_cpu_ptr(bp_cpuinfo + type, cpu);
}

/* Keep track of the breakpoints attached to tasks */
static LIST_HEAD(bp_task_head);

Expand Down Expand Up @@ -96,8 +99,8 @@ static inline enum bp_type_idx find_slot_idx(struct perf_event *bp)
*/
static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type)
{
unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned;
int i;
unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);

for (i = nr_slots[type] - 1; i >= 0; i--) {
if (tsk_pinned[i] > 0)
Expand Down Expand Up @@ -146,8 +149,10 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
int cpu;

for_each_cpu(cpu, cpumask) {
unsigned int nr = per_cpu(nr_cpu_bp_pinned[type], cpu);
struct bp_cpuinfo *info = get_bp_info(cpu, type);
int nr;

nr = info->cpu_pinned;
if (!bp->hw.bp_target)
nr += max_task_bp_pinned(cpu, type);
else
Expand All @@ -156,8 +161,7 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
if (nr > slots->pinned)
slots->pinned = nr;

nr = per_cpu(nr_bp_flexible[type], cpu);

nr = info->flexible;
if (nr > slots->flexible)
slots->flexible = nr;
}
Expand All @@ -180,8 +184,7 @@ fetch_this_slot(struct bp_busy_slots *slots, int weight)
static void toggle_bp_task_slot(struct perf_event *bp, int cpu,
enum bp_type_idx type, int weight)
{
/* tsk_pinned[n-1] is the number of tasks having n>0 breakpoints */
unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned;
int old_idx, new_idx;

old_idx = task_bp_pinned(cpu, bp, type) - 1;
Expand All @@ -208,7 +211,7 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,

/* Pinned counter cpu profiling */
if (!bp->hw.bp_target) {
per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight;
get_bp_info(bp->cpu, type)->cpu_pinned += weight;
return;
}

Expand Down Expand Up @@ -240,8 +243,8 @@ __weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
*
* - If attached to a single cpu, check:
*
* (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu)
* + max(per_cpu(nr_task_bp_pinned, cpu)))) < HBP_NUM
* (per_cpu(info->flexible, cpu) || (per_cpu(info->cpu_pinned, cpu)
* + max(per_cpu(info->tsk_pinned, cpu)))) < HBP_NUM
*
* -> If there are already non-pinned counters in this cpu, it means
* there is already a free slot for them.
Expand All @@ -251,8 +254,8 @@ __weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
*
* - If attached to every cpus, check:
*
* (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *))
* + max(per_cpu(nr_task_bp_pinned, *)))) < HBP_NUM
* (per_cpu(info->flexible, *) || (max(per_cpu(info->cpu_pinned, *))
* + max(per_cpu(info->tsk_pinned, *)))) < HBP_NUM
*
* -> This is roughly the same, except we check the number of per cpu
* bp for every cpu and we keep the max one. Same for the per tasks
Expand All @@ -263,16 +266,16 @@ __weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
*
* - If attached to a single cpu, check:
*
* ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu)
* + max(per_cpu(nr_task_bp_pinned, cpu))) < HBP_NUM
* ((per_cpu(info->flexible, cpu) > 1) + per_cpu(info->cpu_pinned, cpu)
* + max(per_cpu(info->tsk_pinned, cpu))) < HBP_NUM
*
* -> Same checks as before. But now the nr_bp_flexible, if any, must keep
* -> Same checks as before. But now the info->flexible, if any, must keep
* one register at least (or they will never be fed).
*
* - If attached to every cpus, check:
*
* ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *))
* + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM
* ((per_cpu(info->flexible, *) > 1) + max(per_cpu(info->cpu_pinned, *))
* + max(per_cpu(info->tsk_pinned, *))) < HBP_NUM
*/
static int __reserve_bp_slot(struct perf_event *bp)
{
Expand Down Expand Up @@ -622,7 +625,6 @@ static struct pmu perf_breakpoint = {

int __init init_hw_breakpoint(void)
{
unsigned int **task_bp_pinned;
int cpu, err_cpu;
int i;

Expand All @@ -631,10 +633,11 @@ int __init init_hw_breakpoint(void)

for_each_possible_cpu(cpu) {
for (i = 0; i < TYPE_MAX; i++) {
task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu);
*task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i],
GFP_KERNEL);
if (!*task_bp_pinned)
struct bp_cpuinfo *info = get_bp_info(cpu, i);

info->tsk_pinned = kcalloc(nr_slots[i], sizeof(int),
GFP_KERNEL);
if (!info->tsk_pinned)
goto err_alloc;
}
}
Expand All @@ -648,7 +651,7 @@ int __init init_hw_breakpoint(void)
err_alloc:
for_each_possible_cpu(err_cpu) {
for (i = 0; i < TYPE_MAX; i++)
kfree(per_cpu(nr_task_bp_pinned[i], err_cpu));
kfree(get_bp_info(err_cpu, i)->tsk_pinned);
if (err_cpu == cpu)
break;
}
Expand Down

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