diff options
| -rw-r--r-- | include/linux/perf_counter.h | 12 | ||||
| -rw-r--r-- | kernel/perf_counter.c | 109 | ||||
| -rw-r--r-- | kernel/sched.c | 2 |
3 files changed, 107 insertions, 16 deletions
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index 071309005468..4cae01a50450 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -513,6 +513,7 @@ struct perf_counter_context { struct list_head event_list; int nr_counters; int nr_active; + int nr_enabled; int is_active; atomic_t refcount; struct task_struct *task; @@ -522,6 +523,14 @@ struct perf_counter_context { */ u64 time; u64 timestamp; + + /* + * These fields let us detect when two contexts have both + * been cloned (inherited) from a common ancestor. + */ + struct perf_counter_context *parent_ctx; + u32 parent_gen; + u32 generation; }; /** @@ -552,7 +561,8 @@ extern int perf_max_counters; extern const struct pmu *hw_perf_counter_init(struct perf_counter *counter); extern void perf_counter_task_sched_in(struct task_struct *task, int cpu); -extern void perf_counter_task_sched_out(struct task_struct *task, int cpu); +extern void perf_counter_task_sched_out(struct task_struct *task, + struct task_struct *next, int cpu); extern void perf_counter_task_tick(struct task_struct *task, int cpu); extern void perf_counter_init_task(struct task_struct *child); extern void perf_counter_exit_task(struct task_struct *child); diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 06ea3eae886e..c10055416dea 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -104,8 +104,11 @@ static void get_ctx(struct perf_counter_context *ctx) static void put_ctx(struct perf_counter_context *ctx) { - if (atomic_dec_and_test(&ctx->refcount)) + if (atomic_dec_and_test(&ctx->refcount)) { + if (ctx->parent_ctx) + put_ctx(ctx->parent_ctx); kfree(ctx); + } } static void @@ -127,6 +130,8 @@ list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx) list_add_rcu(&counter->event_entry, &ctx->event_list); ctx->nr_counters++; + if (counter->state >= PERF_COUNTER_STATE_INACTIVE) + ctx->nr_enabled++; } /* @@ -141,6 +146,8 @@ list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx) if (list_empty(&counter->list_entry)) return; ctx->nr_counters--; + if (counter->state >= PERF_COUNTER_STATE_INACTIVE) + ctx->nr_enabled--; list_del_init(&counter->list_entry); list_del_rcu(&counter->event_entry); @@ -204,6 +211,22 @@ group_sched_out(struct perf_counter *group_counter, } /* + * Mark this context as not being a clone of another. + * Called when counters are added to or removed from this context. + * We also increment our generation number so that anything that + * was cloned from this context before this will not match anything + * cloned from this context after this. + */ +static void unclone_ctx(struct perf_counter_context *ctx) +{ + ++ctx->generation; + if (!ctx->parent_ctx) + return; + put_ctx(ctx->parent_ctx); + ctx->parent_ctx = NULL; +} + +/* * Cross CPU call to remove a performance counter * * We disable the counter on the hardware level first. After that we @@ -263,6 +286,7 @@ static void perf_counter_remove_from_context(struct perf_counter *counter) struct perf_counter_context *ctx = counter->ctx; struct task_struct *task = ctx->task; + unclone_ctx(ctx); if (!task) { /* * Per cpu counters are removed via an smp call and @@ -378,6 +402,7 @@ static void __perf_counter_disable(void *info) else counter_sched_out(counter, cpuctx, ctx); counter->state = PERF_COUNTER_STATE_OFF; + ctx->nr_enabled--; } spin_unlock_irqrestore(&ctx->lock, flags); @@ -419,6 +444,7 @@ static void perf_counter_disable(struct perf_counter *counter) if (counter->state == PERF_COUNTER_STATE_INACTIVE) { update_counter_times(counter); counter->state = PERF_COUNTER_STATE_OFF; + ctx->nr_enabled--; } spin_unlock_irq(&ctx->lock); @@ -727,6 +753,7 @@ static void __perf_counter_enable(void *info) goto unlock; counter->state = PERF_COUNTER_STATE_INACTIVE; counter->tstamp_enabled = ctx->time - counter->total_time_enabled; + ctx->nr_enabled++; /* * If the counter is in a group and isn't the group leader, @@ -817,6 +844,7 @@ static void perf_counter_enable(struct perf_counter *counter) counter->state = PERF_COUNTER_STATE_INACTIVE; counter->tstamp_enabled = ctx->time - counter->total_time_enabled; + ctx->nr_enabled++; } out: spin_unlock_irq(&ctx->lock); @@ -862,6 +890,25 @@ void __perf_counter_sched_out(struct perf_counter_context *ctx, } /* + * Test whether two contexts are equivalent, i.e. whether they + * have both been cloned from the same version of the same context + * and they both have the same number of enabled counters. + * If the number of enabled counters is the same, then the set + * of enabled counters should be the same, because these are both + * inherited contexts, therefore we can't access individual counters + * in them directly with an fd; we can only enable/disable all + * counters via prctl, or enable/disable all counters in a family + * via ioctl, which will have the same effect on both contexts. + */ +static int context_equiv(struct perf_counter_context *ctx1, + struct perf_counter_context *ctx2) +{ + return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx + && ctx1->parent_gen == ctx2->parent_gen + && ctx1->nr_enabled == ctx2->nr_enabled; +} + +/* * Called from scheduler to remove the counters of the current task, * with interrupts disabled. * @@ -872,10 +919,12 @@ void __perf_counter_sched_out(struct perf_counter_context *ctx, * accessing the counter control register. If a NMI hits, then it will * not restart the counter. */ -void perf_counter_task_sched_out(struct task_struct *task, int cpu) +void perf_counter_task_sched_out(struct task_struct *task, + struct task_struct *next, int cpu) { struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu); struct perf_counter_context *ctx = task->perf_counter_ctxp; + struct perf_counter_context *next_ctx; struct pt_regs *regs; if (likely(!ctx || !cpuctx->task_ctx)) @@ -885,6 +934,16 @@ void perf_counter_task_sched_out(struct task_struct *task, int cpu) regs = task_pt_regs(task); perf_swcounter_event(PERF_COUNT_CONTEXT_SWITCHES, 1, 1, regs, 0); + + next_ctx = next->perf_counter_ctxp; + if (next_ctx && context_equiv(ctx, next_ctx)) { + task->perf_counter_ctxp = next_ctx; + next->perf_counter_ctxp = ctx; + ctx->task = next; + next_ctx->task = task; + return; + } + __perf_counter_sched_out(ctx, cpuctx); cpuctx->task_ctx = NULL; @@ -998,6 +1057,8 @@ void perf_counter_task_sched_in(struct task_struct *task, int cpu) if (likely(!ctx)) return; + if (cpuctx->task_ctx == ctx) + return; __perf_counter_sched_in(ctx, cpuctx, cpu); cpuctx->task_ctx = ctx; } @@ -3253,6 +3314,16 @@ inherit_counter(struct perf_counter *parent_counter, return child_counter; /* + * Make the child state follow the state of the parent counter, + * not its hw_event.disabled bit. We hold the parent's mutex, + * so we won't race with perf_counter_{en,dis}able_family. + */ + if (parent_counter->state >= PERF_COUNTER_STATE_INACTIVE) + child_counter->state = PERF_COUNTER_STATE_INACTIVE; + else + child_counter->state = PERF_COUNTER_STATE_OFF; + + /* * Link it up in the child's context: */ add_counter_to_ctx(child_counter, child_ctx); @@ -3277,16 +3348,6 @@ inherit_counter(struct perf_counter *parent_counter, mutex_lock(&parent_counter->mutex); list_add_tail(&child_counter->child_list, &parent_counter->child_list); - /* - * Make the child state follow the state of the parent counter, - * not its hw_event.disabled bit. We hold the parent's mutex, - * so we won't race with perf_counter_{en,dis}able_family. - */ - if (parent_counter->state >= PERF_COUNTER_STATE_INACTIVE) - child_counter->state = PERF_COUNTER_STATE_INACTIVE; - else - child_counter->state = PERF_COUNTER_STATE_OFF; - mutex_unlock(&parent_counter->mutex); return child_counter; @@ -3429,6 +3490,7 @@ void perf_counter_init_task(struct task_struct *child) struct perf_counter_context *child_ctx, *parent_ctx; struct perf_counter *counter; struct task_struct *parent = current; + int inherited_all = 1; child->perf_counter_ctxp = NULL; @@ -3463,12 +3525,31 @@ void perf_counter_init_task(struct task_struct *child) if (counter != counter->group_leader) continue; - if (!counter->hw_event.inherit) + if (!counter->hw_event.inherit) { + inherited_all = 0; continue; + } if (inherit_group(counter, parent, - parent_ctx, child, child_ctx)) + parent_ctx, child, child_ctx)) { + inherited_all = 0; break; + } + } + + if (inherited_all) { + /* + * Mark the child context as a clone of the parent + * context, or of whatever the parent is a clone of. + */ + if (parent_ctx->parent_ctx) { + child_ctx->parent_ctx = parent_ctx->parent_ctx; + child_ctx->parent_gen = parent_ctx->parent_gen; + } else { + child_ctx->parent_ctx = parent_ctx; + child_ctx->parent_gen = parent_ctx->generation; + } + get_ctx(child_ctx->parent_ctx); } mutex_unlock(&parent_ctx->mutex); diff --git a/kernel/sched.c b/kernel/sched.c index 419a39d0988f..4c0d58bce6b2 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -5091,7 +5091,7 @@ need_resched_nonpreemptible: if (likely(prev != next)) { sched_info_switch(prev, next); - perf_counter_task_sched_out(prev, cpu); + perf_counter_task_sched_out(prev, next, cpu); rq->nr_switches++; rq->curr = next; |
