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authorMatthew Ahrens <[email protected]>2020-06-26 18:05:28 -0700
committerGitHub <[email protected]>2020-06-26 18:05:28 -0700
commit7b232e93548a187beb5490314dad181f9ce6b17c (patch)
tree8776bbb46c8d5200144c6ba77163fa18e79fb4be /man
parentbfcbec6f5d8aad60365eaeacff21df92c04c26df (diff)
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 <[email protected]> Reviewed-by: Pavel Zakharov <[email protected]> Reviewed-by: Tony Nguyen <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> Closes #10494
Diffstat (limited to 'man')
-rw-r--r--man/man1/arcstat.124
1 files changed, 22 insertions, 2 deletions
diff --git a/man/man1/arcstat.1 b/man/man1/arcstat.1
index 6dcc39b67..9113b76af 100644
--- a/man/man1/arcstat.1
+++ b/man/man1/arcstat.1
@@ -236,7 +236,7 @@ Time
.sp
.ne 2
.na
-\fBarcsz \fR
+\fBsize \fR
.ad
.RS 14n
ARC size
@@ -245,6 +245,15 @@ ARC size
.sp
.ne 2
.na
+\fBarcsz \fR
+.ad
+.RS 14n
+Alias for \fBsize\fR
+.RE
+
+.sp
+.ne 2
+.na
\fBdread \fR
.ad
.RS 14n
@@ -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
.\"