Add a new line to top that provides a brief summary of the ZFS ARC memory

usage on hosts using ZFS.  The new line displays the total amount of RAM
used by the ARC along with the size of MFU, MRU, anonymous (in flight),
headers, and other (miscellaneous) sub-categories.  The line is not
displayed on systems that are not using ZFS.

Reviewed by:	avg, fs@
MFC after:	3 days

2 files changed, 84 insertions, 21 deletions

diff --git a/usr.bin/top/machine.c b/usr.bin/top/machine.c
index 59f663d..1d6b907 100644
--- a/usr.bin/top/machine.c
+++ b/usr.bin/top/machine.c
@@ -176,6 +176,12 @@ char *memorynames[] = {
 	"K Free", NULL
 };
 
+int arc_stats[7];
+char *arcnames[] = {
+	"K Total, ", "K MRU, ", "K MFU, ", "K Anon, ", "K Header, ", "K Other",
+	NULL
+};
+
 int swap_stats[7];
 char *swapnames[] = {
 	"K Total, ", "K Used, ", "K Free, ", "% Inuse, ", "K In, ", "K Out",
@@ -194,6 +200,7 @@ static struct kinfo_proc *previous_procs;
 static struct kinfo_proc **previous_pref;
 static int previous_proc_count = 0;
 static int previous_proc_count_max = 0;
+static int arc_enabled;
 
 /* total number of io operations */
 static long total_inblock;
@@ -239,6 +246,7 @@ static int compare_tid(const void *a, const void *b);
 static const char *format_nice(const struct kinfo_proc *pp);
 static void getsysctl(const char *name, void *ptr, size_t len);
 static int swapmode(int *retavail, int *retfree);
+static void update_layout(void);
 
 void
 toggle_pcpustats(void)
@@ -246,24 +254,30 @@ toggle_pcpustats(void)
 
 	if (ncpus == 1)
 		return;
+	update_layout();
+}
+
+/* Adjust display based on ncpus and the ARC state. */
+static void
+update_layout(void)
+{
+
+	y_mem = 3;
+	y_swap = 4 + arc_enabled;
+	y_idlecursor = 5 + arc_enabled;
+	y_message = 5 + arc_enabled;
+	y_header = 6 + arc_enabled;
+	y_procs = 7 + arc_enabled;
+	Header_lines = 7 + arc_enabled;
 
-	/* Adjust display based on ncpus */
 	if (pcpu_stats) {
-		y_mem += ncpus - 1;	/* 3 */
-		y_swap += ncpus - 1;	/* 4 */
-		y_idlecursor += ncpus - 1; /* 5 */
-		y_message += ncpus - 1;	/* 5 */
-		y_header += ncpus - 1;	/* 6 */
-		y_procs += ncpus - 1;	/* 7 */
-		Header_lines += ncpus - 1; /* 7 */
-	} else {
-		y_mem = 3;
-		y_swap = 4;
-		y_idlecursor = 5;
-		y_message = 5;
-		y_header = 6;
-		y_procs = 7;
-		Header_lines = 7;
+		y_mem = ncpus - 1;
+		y_swap += ncpus - 1;
+		y_idlecursor += ncpus - 1;
+		y_message += ncpus - 1;
+		y_header += ncpus - 1;
+		y_procs += ncpus - 1;
+		Header_lines += ncpus - 1;
 	}
 }
 
@@ -271,6 +285,7 @@ int
 machine_init(struct statics *statics, char do_unames)
 {
 	int i, j, empty, pagesize;
+	uint64_t arc_size;
 	size_t size;
 	struct passwd *pw;
 
@@ -282,6 +297,11 @@ machine_init(struct statics *statics, char do_unames)
 	    size != sizeof(smpmode))
 		smpmode = 0;
 
+	size = sizeof(arc_size);
+	if (sysctlbyname("kstat.zfs.misc.arcstats.size", &arc_size, &size,
+	    NULL, 0) == 0 && arc_size != 0)
+		arc_enabled = 1;
+
 	if (do_unames) {
 	    while ((pw = getpwent()) != NULL) {
 		if (strlen(pw->pw_name) > namelength)
@@ -322,6 +342,10 @@ machine_init(struct statics *statics, char do_unames)
 	statics->procstate_names = procstatenames;
 	statics->cpustate_names = cpustatenames;
 	statics->memory_names = memorynames;
+	if (arc_enabled)
+		statics->arc_names = arcnames;
+	else
+		statics->arc_names = NULL;
 	statics->swap_names = swapnames;
 #ifdef ORDER
 	statics->order_names = ordernames;
@@ -356,8 +380,7 @@ machine_init(struct statics *statics, char do_unames)
 	pcpu_cpu_states = calloc(1, size);
 	statics->ncpus = ncpus;
 
-	if (pcpu_stats)
-		toggle_pcpustats();
+	update_layout();
 
 	/* all done! */
 	return (0);
@@ -408,7 +431,7 @@ get_system_info(struct system_info *si)
 	struct loadavg sysload;
 	int mib[2];
 	struct timeval boottime;
-	size_t bt_size;
+	uint64_t arc_stat, arc_stat2;
 	int i, j;
 	size_t size;
 
@@ -487,6 +510,23 @@ get_system_info(struct system_info *si)
 		swap_stats[6] = -1;
 	}
 
+	if (arc_enabled) {
+		GETSYSCTL("kstat.zfs.misc.arcstats.size", arc_stat);
+		arc_stats[0] = arc_stat >> 10;
+		GETSYSCTL("vfs.zfs.mfu_size", arc_stat);
+		arc_stats[1] = arc_stat >> 10;
+		GETSYSCTL("vfs.zfs.mru_size", arc_stat);
+		arc_stats[2] = arc_stat >> 10;
+		GETSYSCTL("vfs.zfs.anon_size", arc_stat);
+		arc_stats[3] = arc_stat >> 10;
+		GETSYSCTL("kstat.zfs.misc.arcstats.hdr_size", arc_stat);
+		GETSYSCTL("kstat.zfs.misc.arcstats.l2_hdr_size", arc_stat2);
+		arc_stats[4] = arc_stat + arc_stat2 >> 10;
+		GETSYSCTL("kstat.zfs.misc.arcstats.other_size", arc_stat);
+		arc_stats[5] = arc_stat >> 10;
+		si->arc = arc_stats;
+	}
+		    
 	/* set arrays and strings */
 	if (pcpu_stats) {
 		si->cpustates = pcpu_cpu_states;
@@ -511,8 +551,8 @@ get_system_info(struct system_info *si)
 	 */
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_BOOTTIME;
-	bt_size = sizeof(boottime);
-	if (sysctl(mib, 2, &boottime, &bt_size, NULL, 0) != -1 &&
+	size = sizeof(boottime);
+	if (sysctl(mib, 2, &boottime, &size, NULL, 0) != -1 &&
 	    boottime.tv_sec != 0) {
 		si->boottime = boottime;
 	} else {
diff --git a/usr.bin/top/top.local.1 b/usr.bin/top/top.local.1
index a674828..864ab8d 100644
--- a/usr.bin/top/top.local.1
+++ b/usr.bin/top/top.local.1
@@ -3,6 +3,7 @@
 
 .SH DESCRIPTION OF MEMORY
 Mem: 9220K Active, 1M Inact, 3284K Wired, 1M Cache, 2M Buf, 1320K Free
+ARC: 2048K Total, 342K MRU, 760K MFU, 272K Anon, 232K Header, 442K Other
 Swap: 91M Total, 79M Free, 13% Inuse, 80K In, 104K Out
 .TP
 .B K:
@@ -16,6 +17,7 @@ Gigabyte
 .TP
 .B %:
 1/100
+.SS Physical Memory Stats
 .TP
 .B Active:
 number of bytes active
@@ -35,6 +37,27 @@ number of bytes used for BIO-level disk caching
 .TP
 .B Free:
 number of bytes free
+.SS ZFS ARC Stats
+These stats are only displayed when the ARC is in use.
+.TP
+.B Total:
+number of wired bytes used for the ZFS ARC
+.TP
+.B MRU:
+number of ARC bytes holding most recently used data
+.TP
+.B MFU:
+number of ARC bytes holding most frequently used data
+.TP
+.B Anon:
+number of ARC bytes holding in flight data
+.TP
+.B Header:
+number of ARC bytes holding headers
+.TP
+.B Other
+miscellaneous ARC bytes
+.SS Swap Stats
 .TP
 .B Total:
 total available swap usage