From 7b232e93548a187beb5490314dad181f9ce6b17c Mon Sep 17 00:00:00 2001 From: Matthew Ahrens Date: Fri, 26 Jun 2020 18:05:28 -0700 Subject: [PATCH] arcstat: add 'avail', fix 'free' The meaning of the `free` field is currently `zfs_arc_sys_free`, which is the target amount of memory to leave free for the system, and is constant after booting. This commit changes the meaning of `free` to arc_free_memory(), the amount of memory that the ARC considers to be free. It also adds a new arcstat field `avail`, which tracks `arc_available_memory()`. Since `avail` can be negative, it also updates the arcstat script to pretty-print negative values. example output: $ arcstat -f time,miss,arcsz,c,grow,need,free,avail 1 time miss arcsz c grow need free avail 15:03:02 39K 114G 114G 0 0 2.4G 407M 15:03:03 42K 114G 114G 0 0 2.1G 120M 15:03:04 40K 114G 114G 0 0 1.8G -177M 15:03:05 24K 113G 112G 0 0 1.7G -269M 15:03:06 29K 111G 110G 0 0 1.6G -385M 15:03:07 27K 110G 108G 0 0 1.4G -535M 15:03:08 13K 108G 108G 0 0 2.2G 239M 15:03:09 33K 107G 107G 0 0 1.3G -639M 15:03:10 16K 105G 102G 0 0 2.6G 704M 15:03:11 7.2K 102G 102G 0 0 5.1G 3.1G 15:03:12 42K 103G 102G 0 0 4.8G 2.8G Reviewed-by: George Melikov Reviewed-by: Pavel Zakharov Reviewed-by: Tony Nguyen Signed-off-by: Matthew Ahrens Closes #10494 --- cmd/arcstat/arcstat | 24 +++++++++++++----------- man/man1/arcstat.1 | 24 ++++++++++++++++++++++-- 2 files changed, 35 insertions(+), 13 deletions(-) diff --git a/cmd/arcstat/arcstat b/cmd/arcstat/arcstat index df2f62d6b2..5ce7e755cb 100755 --- a/cmd/arcstat/arcstat +++ b/cmd/arcstat/arcstat @@ -81,6 +81,7 @@ cols = { "mh%": [3, 100, "Metadata hit percentage"], "mm%": [3, 100, "Metadata miss percentage"], "arcsz": [5, 1024, "ARC size"], + "size": [4, 1024, "ARC size"], "c": [4, 1024, "ARC target size"], "mfu": [4, 1000, "MFU list hits per second"], "mru": [4, 1000, "MRU list hits per second"], @@ -101,11 +102,12 @@ cols = { "grow": [4, 1000, "ARC grow disabled"], "need": [4, 1024, "ARC reclaim need"], "free": [4, 1024, "ARC free memory"], + "avail": [5, 1024, "ARC available memory"], } v = {} hdr = ["time", "read", "miss", "miss%", "dmis", "dm%", "pmis", "pm%", "mmis", - "mm%", "arcsz", "c"] + "mm%", "size", "c", "avail"] xhdr = ["time", "mfu", "mru", "mfug", "mrug", "eskip", "mtxmis", "dread", "pread", "read"] sint = 1 # Default interval is 1 second @@ -225,7 +227,7 @@ def prettynum(sz, scale, num=0): elif 0 < num < 1: num = 0 - while num > scale and index < 5: + while abs(num) > scale and index < 5: save = num num = num / scale index += 1 @@ -233,7 +235,7 @@ def prettynum(sz, scale, num=0): if index == 0: return "%*d" % (sz, num) - if (save / scale) < 10: + if abs(save / scale) < 10: return "%*.1f%s" % (sz - 1, num, suffix[index]) else: return "%*d%s" % (sz - 1, num, suffix[index]) @@ -244,11 +246,9 @@ def print_values(): global sep global v - for col in hdr: - sys.stdout.write("%s%s" % ( - prettynum(cols[col][0], cols[col][1], v[col]), - sep - )) + sys.stdout.write(sep.join( + prettynum(cols[col][0], cols[col][1], v[col]) for col in hdr)) + sys.stdout.write("\n") sys.stdout.flush() @@ -257,8 +257,8 @@ def print_header(): global hdr global sep - for col in hdr: - sys.stdout.write("%*s%s" % (cols[col][0], col, sep)) + sys.stdout.write(sep.join("%*s" % (cols[col][0], col) for col in hdr)) + sys.stdout.write("\n") @@ -428,6 +428,7 @@ def calculate(): v["mm%"] = 100 - v["mh%"] if v["mread"] > 0 else 0 v["arcsz"] = cur["size"] + v["size"] = cur["size"] v["c"] = cur["c"] v["mfu"] = d["mfu_hits"] / sint v["mru"] = d["mru_hits"] / sint @@ -449,7 +450,8 @@ def calculate(): v["grow"] = 0 if cur["arc_no_grow"] else 1 v["need"] = cur["arc_need_free"] - v["free"] = cur["arc_sys_free"] + v["free"] = cur["memory_free_bytes"] + v["avail"] = cur["memory_available_bytes"] def main(): diff --git a/man/man1/arcstat.1 b/man/man1/arcstat.1 index 6dcc39b67f..9113b76af4 100644 --- a/man/man1/arcstat.1 +++ b/man/man1/arcstat.1 @@ -236,12 +236,21 @@ Time .sp .ne 2 .na -\fBarcsz \fR +\fBsize \fR .ad .RS 14n ARC size .RE +.sp +.ne 2 +.na +\fBarcsz \fR +.ad +.RS 14n +Alias for \fBsize\fR +.RE + .sp .ne 2 .na @@ -392,7 +401,18 @@ ARC reclaim needed \fBfree \fR .ad .RS 14n -ARC free memory +The ARC's idea of how much free memory there is, which includes evictable memory in the page cache. +Since the ARC tries to keep \fBavail\fR above zero, \fBavail\fR is usually more instructive to observe than \fBfree\fR. +.RE + +.sp +.ne 2 +.na +\fBavail \fR +.ad +.RS 14n +The ARC's idea of how much free memory is available to it, which is a bit less than \fBfree\fR. +May temporarily be negative, in which case the ARC will reduce the target size \fBc\fR. .RE .\"