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Message-ID: <484db000.0aec660a.2b01.6499@mx.google.com>
Date: Mon, 09 Jun 2008 15:34:40 -0700 (PDT)
From: eranian@...glemail.com
To: linux-kernel@...r.kernel.org
Subject: [patch 15/21] perfmon2 minimal: attach/detach support
This patch adds the attach and detach functionalities. A perfmon
session can be dynamically attached and detached from a thread.
Signed-off-by: Stephane Eranian <eranian@...il.com>
--
Index: o/perfmon/perfmon_attach.c
===================================================================
--- o.orig/perfmon/perfmon_attach.c 2008-06-09 11:17:31.000000000 +0200
+++ o/perfmon/perfmon_attach.c 2008-06-09 11:19:08.000000000 +0200
@@ -42,6 +42,243 @@
#include "perfmon_priv.h"
/**
+ * __pfm_load_ctx_thread - attach context to a thread
+ * @ctx: context to operate on
+ * @task: thread to attach to
+ *
+ * The function must be called with the context locked and interrupts disabled.
+ */
+static int pfm_load_ctx_thread(struct pfm_context *ctx,
+ struct task_struct *task)
+{
+ struct pfm_event_set *set;
+ struct pfm_context *old;
+ int ret;
+ u16 max;
+
+ PFM_DBG("pid=%d", task->pid);
+
+ /*
+ * per-thread:
+ * - task to attach to is checked in sys_pfm_load_context() to avoid
+ * locking issues. if found, and not self, task refcount was
+ * incremented.
+ */
+ old = cmpxchg(&task->pfm_context, NULL, ctx);
+ if (old) {
+ PFM_DBG("load_pid=%d has a context "
+ "old=%p new=%p cur=%p",
+ task->pid,
+ old,
+ ctx,
+ task->pfm_context);
+ return -EEXIST;
+ }
+
+ /*
+ * initialize sets
+ */
+ set = ctx->active_set;
+
+ max = pfm_pmu_conf->regs.max_intr_pmd;
+
+ /*
+ * cleanup bitvectors
+ */
+ bitmap_zero(cast_ulp(set->povfl_pmds), max);
+
+ set->npend_ovfls = 0;
+
+ /*
+ * we cannot just use plain clear because of arch-specific flags
+ */
+ set->priv_flags &= ~PFM_SETFL_PRIV_MOD_BOTH;
+
+ ctx->task = task;
+
+ /*
+ * perform any architecture specific actions
+ */
+ ret = pfm_arch_load_context(ctx);
+ if (ret)
+ goto error_noload;
+
+ /*
+ * now reserve the session, before we can proceed with
+ * actually accessing the PMU hardware
+ */
+ ret = pfm_session_acquire();
+ if (ret)
+ goto error;
+
+
+ if (ctx->task != current) {
+
+ ctx->flags.is_self = 0;
+
+ /* force a full reload */
+ ctx->last_act = PFM_INVALID_ACTIVATION;
+ ctx->last_cpu = -1;
+ set->priv_flags |= PFM_SETFL_PRIV_MOD_BOTH;
+
+ } else {
+ pfm_check_save_prev_ctx();
+
+ ctx->last_cpu = smp_processor_id();
+ __get_cpu_var(pmu_activation_number)++;
+ ctx->last_act = __get_cpu_var(pmu_activation_number);
+
+ ctx->flags.is_self = 1;
+
+ /*
+ * load PMD from set
+ * load PMC from set
+ */
+ pfm_arch_restore_pmds(ctx, set);
+ pfm_arch_restore_pmcs(ctx, set);
+
+ /*
+ * set new ownership
+ */
+ pfm_set_pmu_owner(ctx->task, ctx);
+ }
+ set_tsk_thread_flag(task, TIF_PERFMON_CTXSW);
+
+ ctx->state = PFM_CTX_LOADED;
+
+ return 0;
+
+error:
+ pfm_arch_unload_context(ctx);
+ ctx->task = NULL;
+error_noload:
+ /*
+ * detach context
+ */
+ task->pfm_context = NULL;
+ return ret;
+}
+
+/**
+ * __pfm_load_context - attach context to a thread
+ * @ctx: context to operate on
+ * @task: thread to attach to
+ */
+int __pfm_load_context(struct pfm_context *ctx, struct task_struct *task)
+{
+ return pfm_load_ctx_thread(ctx, task);
+}
+
+/**
+ * pfm_update_ovfl_pmds - account for pending ovfls on PMDs
+ * @ctx: context to operate on
+ *
+ * This function is always called after pfm_stop has been issued
+ */
+static void pfm_update_ovfl_pmds(struct pfm_context *ctx)
+{
+ struct pfm_event_set *set;
+ u64 *cnt_pmds;
+ u64 ovfl_mask;
+ u16 num_ovfls, i;
+
+ ovfl_mask = pfm_pmu_conf->ovfl_mask;
+ cnt_pmds = pfm_pmu_conf->regs.cnt_pmds;
+ set = ctx->active_set;
+
+ if (!set->npend_ovfls)
+ return;
+
+ num_ovfls = set->npend_ovfls;
+ PFM_DBG("novfls=%u", num_ovfls);
+
+ for (i = 0; num_ovfls; i++) {
+ if (test_bit(i, cast_ulp(set->povfl_pmds))) {
+ /* only correct value for counters */
+ if (test_bit(i, cast_ulp(cnt_pmds)))
+ set->pmds[i].value += 1 + ovfl_mask;
+ num_ovfls--;
+ }
+ PFM_DBG("pmd%u val=0x%llx",
+ i,
+ (unsigned long long)set->pmds[i].value);
+ }
+ /*
+ * we need to clear to prevent a pfm_getinfo_evtsets() from
+ * returning stale data even after the context is unloaded
+ */
+ set->npend_ovfls = 0;
+ bitmap_zero(cast_ulp(set->povfl_pmds),
+ pfm_pmu_conf->regs.max_intr_pmd);
+}
+
+/**
+ * __pfm_unload_context - detach context from CPU or thread
+ * @ctx: context to operate on
+ *
+ * The function must be called with the context locked and interrupts disabled.
+ */
+int __pfm_unload_context(struct pfm_context *ctx)
+{
+ int ret;
+
+ PFM_DBG("ctx_state=%d task [%d]",
+ ctx->state,
+ ctx->task ? ctx->task->pid : -1);
+
+ /*
+ * check unload-able state
+ */
+ if (ctx->state == PFM_CTX_UNLOADED)
+ return -EINVAL;
+
+ /*
+ * stop monitoring
+ */
+ ret = __pfm_stop(ctx);
+ if (ret)
+ return ret;
+
+ ctx->state = PFM_CTX_UNLOADED;
+
+ /*
+ * save active set
+ * UP:
+ * if not current task and due to lazy, state may
+ * still be live
+ * for system-wide, guaranteed to run on correct CPU
+ */
+ if (__get_cpu_var(pmu_ctx) == ctx) {
+ /*
+ * pending overflows have been saved by pfm_stop()
+ */
+ pfm_save_pmds(ctx);
+ pfm_set_pmu_owner(NULL, NULL);
+ PFM_DBG("released ownership");
+ }
+
+ /*
+ * account for pending overflows
+ */
+ pfm_update_ovfl_pmds(ctx);
+
+ /*
+ * arch-specific unload operations
+ */
+ pfm_arch_unload_context(ctx);
+
+ /*
+ * per-thread: disconnect from monitored task
+ */
+ if (ctx->task) {
+ ctx->task->pfm_context = NULL;
+ clear_tsk_thread_flag(ctx->task, TIF_PERFMON_CTXSW);
+ ctx->task = NULL;
+ }
+ return 0;
+}
+
+/**
* __pfm_exit_thread - detach and free context on thread exit
*/
void __pfm_exit_thread(void)
Index: o/perfmon/perfmon_priv.h
===================================================================
--- o.orig/perfmon/perfmon_priv.h 2008-06-09 11:18:31.000000000 +0200
+++ o/perfmon/perfmon_priv.h 2008-06-09 11:19:08.000000000 +0200
@@ -60,6 +60,9 @@
int __pfm_stop(struct pfm_context *ctx);
int __pfm_start(struct pfm_context *ctx);
+int __pfm_load_context(struct pfm_context *ctx, struct task_struct *task);
+int __pfm_unload_context(struct pfm_context *ctx);
+
ssize_t pfm_sysfs_res_show(char *buf, size_t sz, int what);
int pfm_pmu_acquire(void);
--
--
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