From e64ba55dd29fe8ff5cd38fa614ad1a1b36effa87 Mon Sep 17 00:00:00 2001
From: "Jonathan T. Looney" <jtl@FreeBSD.org>
Date: Mon, 16 Nov 2015 15:16:09 +0000
Subject: [PATCH] Change the driver stats to what they really are: unsigned
 values.

When pmcstat exits after some samples were dropped, give the user an
idea of how many were lost. (Granted, these are global numbers, but
they may still help quantify the scope of the loss.)

Differential Revision:	https://reviews.freebsd.org/D4123
Approved by:	gnn (mentor)
MFC after:	1 month
Sponsored by:	Juniper Networks
---
 lib/libpmc/pmc.h           | 17 +++++++++--------
 sys/sys/pmc.h              | 17 +++++++++--------
 usr.sbin/pmcstat/pmcstat.c | 18 ++++++++++++++----
 3 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/lib/libpmc/pmc.h b/lib/libpmc/pmc.h
index 81672d21d56c..f237285121f4 100644
--- a/lib/libpmc/pmc.h
+++ b/lib/libpmc/pmc.h
@@ -37,14 +37,15 @@
  * Driver statistics.
  */
 struct pmc_driverstats {
-	int	pm_intr_ignored;	/* #interrupts ignored */
-	int	pm_intr_processed;	/* #interrupts processed */
-	int	pm_intr_bufferfull;	/* #interrupts with ENOSPC */
-	int	pm_syscalls;		/* #syscalls */
-	int	pm_syscall_errors;	/* #syscalls with errors */
-	int	pm_buffer_requests;	/* #buffer requests */
-	int	pm_buffer_requests_failed; /* #failed buffer requests */
-	int	pm_log_sweeps;		/* #sample buffer processing passes */
+	unsigned int	pm_intr_ignored;	/* #interrupts ignored */
+	unsigned int	pm_intr_processed;	/* #interrupts processed */
+	unsigned int	pm_intr_bufferfull;	/* #interrupts with ENOSPC */
+	unsigned int	pm_syscalls;		/* #syscalls */
+	unsigned int	pm_syscall_errors;	/* #syscalls with errors */
+	unsigned int	pm_buffer_requests;	/* #buffer requests */
+	unsigned int	pm_buffer_requests_failed; /* #failed buffer requests */
+	unsigned int	pm_log_sweeps;		/* #sample buffer processing
+						   passes */
 };
 
 /*
diff --git a/sys/sys/pmc.h b/sys/sys/pmc.h
index 6ed909bf143f..47662fab48d7 100644
--- a/sys/sys/pmc.h
+++ b/sys/sys/pmc.h
@@ -550,14 +550,15 @@ struct pmc_op_configurelog {
  */
 
 struct pmc_op_getdriverstats {
-	int	pm_intr_ignored;	/* #interrupts ignored */
-	int	pm_intr_processed;	/* #interrupts processed */
-	int	pm_intr_bufferfull;	/* #interrupts with ENOSPC */
-	int	pm_syscalls;		/* #syscalls */
-	int	pm_syscall_errors;	/* #syscalls with errors */
-	int	pm_buffer_requests;	/* #buffer requests */
-	int	pm_buffer_requests_failed; /* #failed buffer requests */
-	int	pm_log_sweeps;		/* #sample buffer processing passes */
+	unsigned int	pm_intr_ignored;	/* #interrupts ignored */
+	unsigned int	pm_intr_processed;	/* #interrupts processed */
+	unsigned int	pm_intr_bufferfull;	/* #interrupts with ENOSPC */
+	unsigned int	pm_syscalls;		/* #syscalls */
+	unsigned int	pm_syscall_errors;	/* #syscalls with errors */
+	unsigned int	pm_buffer_requests;	/* #buffer requests */
+	unsigned int	pm_buffer_requests_failed; /* #failed buffer requests */
+	unsigned int	pm_log_sweeps;		/* #sample buffer processing
+						   passes */
 };
 
 /*
diff --git a/usr.sbin/pmcstat/pmcstat.c b/usr.sbin/pmcstat/pmcstat.c
index 914fc17d1f8e..e75b93782a06 100644
--- a/usr.sbin/pmcstat/pmcstat.c
+++ b/usr.sbin/pmcstat/pmcstat.c
@@ -1500,14 +1500,24 @@ main(int argc, char **argv)
 			    "ERROR: Cannot retrieve driver statistics");
 		if (ds_start.pm_intr_bufferfull != ds_end.pm_intr_bufferfull &&
 		    args.pa_verbosity > 0)
-			warnx("WARNING: some samples were dropped.\n"
-"Please consider tuning the \"kern.hwpmc.nsamples\" tunable."
+			warnx(
+"WARNING: sampling was paused at least %u time%s.\n"
+"Please consider tuning the \"kern.hwpmc.nsamples\" tunable.",
+			    ds_end.pm_intr_bufferfull -
+			    ds_start.pm_intr_bufferfull,
+			    ((ds_end.pm_intr_bufferfull -
+			    ds_start.pm_intr_bufferfull) != 1) ? "s" : ""
 			    );
 		if (ds_start.pm_buffer_requests_failed !=
 		    ds_end.pm_buffer_requests_failed &&
 		    args.pa_verbosity > 0)
-			warnx("WARNING: some events were discarded.\n"
-"Please consider tuning the \"kern.hwpmc.nbuffers\" tunable."
+			warnx(
+"WARNING: at least %u event%s were discarded while running.\n"
+"Please consider tuning the \"kern.hwpmc.nbuffers\" tunable.",
+	 		    ds_end.pm_buffer_requests_failed -
+			    ds_start.pm_buffer_requests_failed,
+			    ((ds_end.pm_buffer_requests_failed -
+			    ds_start.pm_buffer_requests_failed) != 1) ? "s" : ""
 			    );
 	}