ifpps: Always display the least heavy hitter CPU

Along with the topmost heavy hitters, we always display the least heavy
hitter (unless there's only 1 CPU). This is not influenced by the -n
command line parameter, so also display the according additional CPU in
the header line.

Also update the manpage accordingly.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

2 files changed, 44 insertions, 19 deletions

diff --git a/ifpps.8 b/ifpps.8
index a0766f7..6934493 100644
--- a/ifpps.8
+++ b/ifpps.8
@@ -37,8 +37,10 @@ statistics, which are also fairly reliable under high packet load.
 ifpps also periodically displays CPU load, interrupt, software interrupt
 data per sample interval as well as total interrupts, all per CPU. In case
 the number of CPUs exceeds 10 or the number specified by the user with the
-\[lq]\-n\[rq] command line option, ifpps will only display the top heavy
-hitters.
+\[lq]\-n\[rq] command line option, ifpps will only display this number top
+heavy hitters. The topmost heavy hitter CPU will be marked with \[lq]+\[rq].
+The least heavy hitter will always be displayed and is marked with
+\[lq]-\[rq].
 .PP
 .SH OPTIONS
 .PP
diff --git a/ifpps.c b/ifpps.c
index 3a83043..cc659b2 100644
--- a/ifpps.c
+++ b/ifpps.c
@@ -618,6 +618,7 @@ static void screen_header(WINDOW *screen, const char *ifname, int *voff,
 	struct ethtool_drvinfo drvinf;
 	u32 rate = device_bitrate(ifname);
 	int link = ethtool_link(ifname);
+	unsigned int cpus = get_number_cpus();
 
 	memset(&drvinf, 0, sizeof(drvinf));
 	ethtool_drvinf(ifname, &drvinf);
@@ -630,9 +631,10 @@ static void screen_header(WINDOW *screen, const char *ifname, int *voff,
 				link == 0 ? "no" : "yes");
 
 	mvwprintw(screen, (*voff)++, 2,
-		  "Kernel net/sys statistics for %s (%s%s), t=%lums, cpus=%u/%u"
+		  "Kernel net/sys statistics for %s (%s%s), t=%lums, cpus=%u%s/%u"
 		  "               ",
-		  ifname, drvinf.driver, buff, ms_interval, top_cpus, get_number_cpus());
+		  ifname, drvinf.driver, buff, ms_interval, top_cpus,
+		  top_cpus > 0 && top_cpus < cpus ? "+1" : "", cpus);
 }
 
 static void screen_net_dev_rel(WINDOW *screen, const struct ifstat *rel,
@@ -692,29 +694,50 @@ static void screen_sys_mem(WINDOW *screen, const struct ifstat *rel,
 		  abs->procs_run, abs->procs_iow);
 }
 
+static void screen_percpu_states_one(WINDOW *screen, const struct ifstat *rel,
+				     int *voff, unsigned int idx, char *tag)
+{
+	int max_padd = padding_from_num(get_number_cpus());
+	uint64_t all = rel->cpu_user[idx] + rel->cpu_nice[idx] + rel->cpu_sys[idx] +
+		       rel->cpu_idle[idx] + rel->cpu_iow[idx];
+
+	mvwprintw(screen, (*voff)++, 2,
+		  "cpu%*d%s:%s %13.1lf%% usr/t "
+			  "%9.1lf%% sys/t "
+			  "%10.1lf%% idl/t "
+			  "%11.1lf%% iow/t  ", max_padd, idx,
+		  tag, strlen(tag) == 0 ? " " : "",
+		  100.0 * (rel->cpu_user[idx] + rel->cpu_nice[idx]) / all,
+		  100.0 * rel->cpu_sys[idx] / all,
+		  100.0 * rel->cpu_idle[idx] / all,
+		  100.0 * rel->cpu_iow[idx] / all);
+}
+
 static void screen_percpu_states(WINDOW *screen, const struct ifstat *rel,
 				 int top_cpus, int *voff)
 {
 	int i;
-	uint64_t all;
-	int max_padd = padding_from_num(get_number_cpus());
+	int cpus = get_number_cpus();
 
-	for (i = 0; i < top_cpus; ++i) {
-		unsigned int idx = cpu_hits[i].idx;
+	if (top_cpus == 0)
+		return;
 
-		all = rel->cpu_user[idx] + rel->cpu_nice[idx] + rel->cpu_sys[idx] +
-		      rel->cpu_idle[idx] + rel->cpu_iow[idx];
+	/* Display top hitter */
+	screen_percpu_states_one(screen, rel, voff, cpu_hits[0].idx, "+");
 
-		mvwprintw(screen, (*voff)++, 2,
-			  "cpu%*d: %13.1lf%% usr/t "
-				  "%9.1lf%% sys/t "
-				  "%10.1lf%% idl/t "
-				  "%11.1lf%% iow/t  ", max_padd, idx,
-			  100.0 * (rel->cpu_user[idx] + rel->cpu_nice[idx]) / all,
-			  100.0 * rel->cpu_sys[idx] / all,
-			  100.0 * rel->cpu_idle[idx] / all,
-			  100.0 * rel->cpu_iow[idx] / all);
+	/* Make sure we don't display the min. hitter twice */
+	if (top_cpus == cpus)
+		top_cpus--;
+
+	for (i = 1; i < top_cpus; ++i) {
+		unsigned int idx = cpu_hits[i].idx;
+
+		screen_percpu_states_one(screen, rel, voff, idx, "");
 	}
+
+	/* Display minimum hitter */
+	if (cpus != 1)
+		screen_percpu_states_one(screen, rel, voff, cpu_hits[cpus - 1].idx, "-");
 }
 
 static void screen_percpu_irqs_rel(WINDOW *screen, const struct ifstat *rel,