Fix up arcstat(1) to match our version

Turns out the illumos manpage, which is what this originates from, was
written for the original Perl version of the utility which is not the
version in the OpenZFS tree. *That* version originates from a Python
rewrite that was done for FreeNAS. So fix up the manpage to match what
we actually ship (and fix a few typos in the process).

Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: AJ Jordan <alex@strugee.net>
Closes #10288

man/man1/Makefile.am

@@ -1,4 +1,4 @@
-dist_man_MANS = zhack.1 ztest.1 raidz_test.1 zvol_wait.1
+dist_man_MANS = zhack.1 ztest.1 raidz_test.1 zvol_wait.1 arcstat.1
 EXTRA_DIST = cstyle.1
 
 install-data-local:

man/man1/arcstat.1

@@ -11,15 +11,15 @@
 .\"
 .\" Copyright 2014 Adam Stevko.  All rights reserved.
 .\" Copyright (c) 2015 by Delphix. All rights reserved.
+.\" Copyright (c) 2020 by AJ Jordan. All rights reserved.
 .\"
-.TH ARCSTAT 1M "Feb 4, 2014"
+.TH ARCSTAT 1 "May 7, 2020"
 .SH NAME
 arcstat \- report ZFS ARC and L2ARC statistics
 .SH SYNOPSIS
 .LP
 .nf
-\fBarcstat\fR [\fB-hvxr\fR] [\fB-f field[,field]...\fR] [\fB-o file\fR] [\fB-s string\fR] 
+\fBarcstat\fR [\fB-hvx\fR] [\fB-f field[,field]...\fR] [\fB-o file\fR] [\fB-s string\fR] [\fBinterval\fR [\fBcount\fR]]
-      [\fBinterval\fR [\fBcount\fR]]
 .fi
 
 .SH DESCRIPTION
@@ -41,7 +41,7 @@ The \fBarcstat\fR command reports the following information:
 \fBc \fR
 .ad
 .RS 14n
-ARC Target Size
+ARC target size
 .RE
 
 .sp
@@ -50,7 +50,7 @@ ARC Target Size
 \fBdh% \fR
 .ad
 .RS 14n
-Demand Data hit percentage
+Demand data hit percentage
 .RE
 
 .sp
@@ -59,7 +59,7 @@ Demand Data hit percentage
 \fBdm% \fR
 .ad
 .RS 14n
-Demand Data miss percentage
+Demand data miss percentage
 .RE
 
 .sp
@@ -68,7 +68,7 @@ Demand Data miss percentage
 \fBmfu \fR
 .ad
 .RS 14n
-MFU List hits per second
+MFU list hits per second
 .RE
 
 .sp
@@ -95,7 +95,7 @@ Metadata miss percentage
 \fBmru \fR
 .ad
 .RS 14n
-MRU List hits per second
+MRU list hits per second
 .RE
 
 .sp
@@ -122,7 +122,7 @@ Prefetch miss percentage
 \fBdhit \fR
 .ad
 .RS 14n
-Demand Data hits per second
+Demand data hits per second
 .RE
 
 .sp
@@ -131,7 +131,7 @@ Demand Data hits per second
 \fBdmis \fR
 .ad
 .RS 14n
-Demand Data misses per second
+Demand data misses per second
 .RE
 
 .sp
@@ -140,7 +140,7 @@ Demand Data misses per second
 \fBhit% \fR
 .ad
 .RS 14n
-ARC Hit percentage
+ARC hit percentage
 .RE
 
 .sp
@@ -158,7 +158,7 @@ ARC reads per second
 \fBmfug \fR
 .ad
 .RS 14n
-MFU Ghost List hits per second
+MFU ghost list hits per second
 .RE
 
 .sp
@@ -194,7 +194,7 @@ Metadata misses per second
 \fBmrug \fR
 .ad
 .RS 14n
-MRU Ghost List hits per second
+MRU ghost list hits per second
 .RE
 
 .sp
@@ -239,7 +239,7 @@ Time
 \fBarcsz \fR
 .ad
 .RS 14n
-ARC Size
+ARC size
 .RE
 
 .sp
@@ -347,7 +347,7 @@ mutex_miss per second
 \fBl2bytes \fR
 .ad
 .RS 14n
-bytes read per second from the L2ARC
+Bytes read per second from the L2ARC
 .RE
 
 .sp
@@ -367,6 +367,33 @@ L2ARC access miss percentage
 .RS 14n
 Actual (compressed) size of the L2ARC
 .RE
+
+.sp
+.ne 2
+.na
+\fBgrow \fR
+.ad
+.RS 14n
+ARC grow disabled
+.RE
+
+.sp
+.ne 2
+.na
+\fBneed \fR
+.ad
+.RS 14n
+ARC reclaim needed
+.RE
+
+.sp
+.ne 2
+.na
+\fBfree \fR
+.ad
+.RS 14n
+ARC free memory
+.RE
 .\"
 
 .SH OPTIONS
@@ -413,7 +440,6 @@ Display data with a specified separator (default: 2 spaces).
 .ne 2
 .na
 \fB\fB-x\fR\fR
-
 .ad
 .RS 12n
 Print extended stats (same as -f time,mfu,mru,mfug,mrug,eskip,mtxmis,dread,pread,read).
@@ -451,5 +477,6 @@ Specify the sampling interval in seconds.
 
 .SH AUTHORS
 .LP
-arcstat was originally written by Neelakanth Nadgir and supported only ZFS ARC statistics.
+arcstat was originally written in Perl by Neelakanth Nadgir and supported only ZFS ARC statistics.
 Mike Harsch updated it to support L2ARC statistics.
+John Hixson ported it to Python for FreeNAS over some beer, after which many individuals from the OpenZFS community continued to maintain and improve it.