Add a flush of the current PMC log buffer before displaying the next top.

As the underlying block is 4KB if the PMC throughput is low the measurement
will be reported on the next tick. pmcstat(8) use the modified flush API to
reclaim current buffer before displaying next top.

MFC after:	1 month

2 files changed, 61 insertions, 18 deletions

diff --git a/sys/dev/hwpmc/hwpmc_logging.c b/sys/dev/hwpmc/hwpmc_logging.c
index c0f8b0d..5f5cd90 100644
--- a/sys/dev/hwpmc/hwpmc_logging.c
+++ b/sys/dev/hwpmc/hwpmc_logging.c
@@ -238,7 +238,7 @@ pmclog_get_buffer(struct pmc_owner *po)
 static void
 pmclog_loop(void *arg)
 {
-	int error, last_buffer;
+	int error;
 	struct pmc_owner *po;
 	struct pmclog_buffer *lb;
 	struct proc *p;
@@ -253,7 +253,6 @@ pmclog_loop(void *arg)
 	p = po->po_owner;
 	td = curthread;
 	mycred = td->td_ucred;
-	last_buffer = 0;
 
 	PROC_LOCK(p);
 	ownercred = crhold(p->p_ucred);
@@ -286,14 +285,22 @@ pmclog_loop(void *arg)
 			if ((lb = TAILQ_FIRST(&po->po_logbuffers)) == NULL) {
 				mtx_unlock_spin(&po->po_mtx);
 
+				if (po->po_flags & PMC_PO_SHUTDOWN) {
+					mtx_unlock(&pmc_kthread_mtx);
+					/*
+			 		 * Close the file to get PMCLOG_EOF
+					 * error in pmclog(3).
+					 */
+					fo_close(po->po_file, curthread);
+					mtx_lock(&pmc_kthread_mtx);
+				}
+
 				(void) msleep(po, &pmc_kthread_mtx, PWAIT,
 				    "pmcloop", 0);
 				continue;
 			}
 
 			TAILQ_REMOVE(&po->po_logbuffers, lb, plb_next);
-			if (po->po_flags & PMC_PO_SHUTDOWN)
-				last_buffer = TAILQ_EMPTY(&po->po_logbuffers);
 			mtx_unlock_spin(&po->po_mtx);
 		}
 
@@ -336,14 +343,6 @@ pmclog_loop(void *arg)
 			break;
 		}
 
-		if (last_buffer) {
-			/*
-			 * Close the file to get PMCLOG_EOF error
-			 * in pmclog(3).
-			 */
-			fo_close(po->po_file, curthread);
-		}
-
 		mtx_lock(&pmc_kthread_mtx);
 
 		/* put the used buffer back into the global pool */
@@ -693,6 +692,7 @@ int
 pmclog_flush(struct pmc_owner *po)
 {
 	int error;
+	struct pmclog_buffer *lb;
 
 	PMCDBG(LOG,FLS,1, "po=%p", po);
 
@@ -715,11 +715,38 @@ pmclog_flush(struct pmc_owner *po)
 	}
 
 	/*
-	 * Schedule the current buffer if any.
+	 * Schedule the current buffer if any and not empty.
+	 */
+	mtx_lock_spin(&po->po_mtx);
+	lb = po->po_curbuf;
+	if (lb && lb->plb_ptr != lb->plb_base) {
+		pmclog_schedule_io(po);
+	} else
+		error = ENOBUFS;
+	mtx_unlock_spin(&po->po_mtx);
+
+ error:
+	mtx_unlock(&pmc_kthread_mtx);
+
+	return (error);
+}
+
+int
+pmclog_close(struct pmc_owner *po)
+{
+
+	PMCDBG(LOG,CLO,1, "po=%p", po);
+
+	mtx_lock(&pmc_kthread_mtx);
+
+	/*
+	 * Schedule the current buffer.
 	 */
 	mtx_lock_spin(&po->po_mtx);
 	if (po->po_curbuf)
 		pmclog_schedule_io(po);
+	else
+		wakeup_one(po);
 	mtx_unlock_spin(&po->po_mtx);
 
 	/*
@@ -728,13 +755,11 @@ pmclog_flush(struct pmc_owner *po)
 	 */
 	po->po_flags |= PMC_PO_SHUTDOWN;
 
- error:
 	mtx_unlock(&pmc_kthread_mtx);
 
-	return (error);
+	return (0);
 }
 
-
 void
 pmclog_process_callchain(struct pmc *pm, struct pmc_sample *ps)
 {
diff --git a/sys/dev/hwpmc/hwpmc_mod.c b/sys/dev/hwpmc/hwpmc_mod.c
index fc82908..7ca7a47 100644
--- a/sys/dev/hwpmc/hwpmc_mod.c
+++ b/sys/dev/hwpmc/hwpmc_mod.c
@@ -2891,7 +2891,7 @@ pmc_syscall_handler(struct thread *td, void *syscall_args)
 			error = pmclog_configure_log(md, po, cl.pm_logfd);
 		} else if (po->po_flags & PMC_PO_OWNS_LOGFILE) {
 			pmclog_process_closelog(po);
-			error = pmclog_flush(po);
+			error = pmclog_close(po);
 			if (error == 0) {
 				LIST_FOREACH(pm, &po->po_pmcs, pm_next)
 				    if (pm->pm_flags & PMC_F_NEEDS_LOGFILE &&
@@ -2907,7 +2907,6 @@ pmc_syscall_handler(struct thread *td, void *syscall_args)
 	}
 	break;
 
-
 	/*
 	 * Flush a log file.
 	 */
@@ -2928,6 +2927,25 @@ pmc_syscall_handler(struct thread *td, void *syscall_args)
 	break;
 
 	/*
+	 * Close a log file.
+	 */
+
+	case PMC_OP_CLOSELOG:
+	{
+		struct pmc_owner *po;
+
+		sx_assert(&pmc_sx, SX_XLOCKED);
+
+		if ((po = pmc_find_owner_descriptor(td->td_proc)) == NULL) {
+			error = EINVAL;
+			break;
+		}
+
+		error = pmclog_close(po);
+	}
+	break;
+
+	/*
 	 * Retrieve hardware configuration.
 	 */