zfs_arc: support for zfsonlinux

The plugin is structured for Solaris & FreeBSD's get_kstat_value() &
sysctlbyname() functions, which return a single metric based on its
name. ZFS-on-Linux publishes all the stats together in a file in /proc,
which is quite a different approach.
So the idea is to simulate the Solaris/FreeBSD way of doing by using
llist_search() on a linked-list containing all the key/values from the
/proc file. This prevents having to parse it over and over again for
each metric we request.

diff --git a/configure.ac b/configure.ac
index d3687b3..068acdc 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -4860,6 +4860,7 @@ then
        plugin_vmem="yes"
        plugin_vserver="yes"
        plugin_wireless="yes"
+       plugin_zfs_arc="yes"
 
        if test "x$have_linux_ip_vs_h" = "xyes" || test "x$have_net_ip_vs_h" = "xyes" || test "x$have_ip_vs_h" = "xyes"
        then

diff --git a/src/Makefile.am b/src/Makefile.am
index a9d8582..487be23 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1435,8 +1435,13 @@ zfs_arc_la_LDFLAGS = -module -avoid-version
 if BUILD_FREEBSD
 zfs_arc_la_LIBADD = -lm
 else
+if BUILD_LINUX
+# zfs_arc requires no library on linux
+else
+# solaris
 zfs_arc_la_LIBADD = -lkstat
 endif
+endif
 collectd_LDADD += "-dlopen" zfs_arc.la
 collectd_DEPENDENCIES += zfs_arc.la
 endif

diff --git a/src/zfs_arc.c b/src/zfs_arc.c
index 96ffc54..4190a71 100644 (file)
--- a/src/zfs_arc.c
+++ b/src/zfs_arc.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2009  Anthony Dewhurst
  * Copyright (C) 2012  Aurelien Rougemont
  * Copyright (C) 2013  Xin Li
+ * Copyright (C) 2014  Marc Fournier
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -21,6 +22,7 @@
  *   Anthony Dewhurst <dewhurst at gmail>
  *   Aurelien Rougemont <beorn at gandi.net>
  *   Xin Li <delphij at FreeBSD.org>
+ *   Marc Fournier <marc.fournier at camptocamp.com>
  **/
 
 #include "collectd.h"
@@ -31,7 +33,31 @@
  * Global variables
  */
 
-#if !defined(__FreeBSD__)
+#if defined(KERNEL_LINUX)
+#include "utils_llist.h"
+#define ZOL_ARCSTATS_FILE "/proc/spl/kstat/zfs/arcstats"
+
+#if !defined(kstat_t)
+typedef void kstat_t;
+static llist_t *zfs_stats = NULL;
+#endif
+
+static long long get_zfs_value(kstat_t *dummy __attribute__((unused)),
+               char *name)
+{
+       llentry_t *e;
+
+       e = llist_search (zfs_stats, name);
+       if (e == NULL)
+       {
+               ERROR ("zfs_arc plugin: `llist_search` failed for key: '%s'.", name);
+               return (-1);
+       }
+
+       return ((long long int)e->value);
+}
+
+#elif !defined(__FreeBSD__) // Solaris
 extern kstat_ctl_t *kc;
 
 static long long get_zfs_value(kstat_t *ksp, char *name)
@@ -39,7 +65,7 @@ static long long get_zfs_value(kstat_t *ksp, char *name)
 
        return (get_kstat_value(ksp, name));
 }
-#else
+#else // FreeBSD
 #include <sys/types.h>
 #include <sys/sysctl.h>
 
@@ -147,7 +173,70 @@ static int za_read (void)
        value_t  l2_io[2];
        kstat_t  *ksp   = NULL;
 
-#if !defined(__FreeBSD__)
+#if KERNEL_LINUX
+       FILE *fh;
+
+       char buf[1024];
+       char *fields[3];
+       int numfields;
+
+       if ((fh = fopen (ZOL_ARCSTATS_FILE, "r")) == NULL)
+       {
+               char errbuf[1024];
+               ERROR ("zfs_arc plugin: `fopen (%s)' failed: %s",
+                       ZOL_ARCSTATS_FILE,
+                       sstrerror (errno, errbuf, sizeof (errbuf)));
+               return (-1);
+       }
+
+       zfs_stats = llist_create ();
+       if (zfs_stats == NULL)
+       {
+               ERROR ("zfs_arc plugin: `llist_create' failed.");
+               fclose (fh);
+               return (-1);
+       }
+
+       while (fgets (buf, 1024, fh) != NULL)
+       {
+               numfields = strsplit (buf, fields, 4);
+               if (numfields != 3)
+                       continue;
+
+               char *llkey;
+               long long int llvalue;
+
+               llkey = strdup (fields[0]);
+               if (llkey == NULL) {
+                       char errbuf[1024];
+                       ERROR ("zfs_arc plugin: `strdup' failed: %s",
+                               sstrerror (errno, errbuf, sizeof (errbuf)));
+                       continue;
+               }
+
+               llvalue = atoll (fields[2]);
+
+               llentry_t *e;
+               e = llentry_create (llkey, (void *)llvalue);
+               if (e == NULL)
+               {
+                       ERROR ("zfs_arc plugin: `llentry_create' failed.");
+                       free (llkey);
+                       continue;
+               }
+
+               free (llkey);
+
+               llist_append (zfs_stats, e);
+       }
+
+       if (fclose (fh))
+       {
+               char errbuf[1024];
+               WARNING ("zfs_arc: `fclose' failed: %s", sstrerror (errno, errbuf, sizeof (errbuf)));
+       }
+
+#elif !defined(__FreeBSD__) // Solaris
        get_kstat (&ksp, "zfs", 0, "arcstats");
        if (ksp == NULL)
        {
@@ -170,7 +259,7 @@ static int za_read (void)
        /* Issue indicators */
        za_read_derive (ksp, "mutex_miss", "mutex_operations", "miss");
        za_read_derive (ksp, "hash_collisions", "hash_collisions", "");
-       
+
        /* Evictions */
        za_read_derive (ksp, "evict_l2_cached",     "cache_eviction", "cached");
        za_read_derive (ksp, "evict_l2_eligible",   "cache_eviction", "eligible");
@@ -201,12 +290,19 @@ static int za_read (void)
 
        za_submit ("io_octets", "L2", l2_io, /* num values = */ 2);
 
+#if defined(KERNEL_LINUX)
+       if (zfs_stats != NULL)
+       {
+               llist_destroy (zfs_stats);
+       }
+#endif
+
        return (0);
 } /* int za_read */
 
 static int za_init (void) /* {{{ */
 {
-#if !defined(__FreeBSD__)
+#if !defined(__FreeBSD__) && !defined(KERNEL_LINUX) // Solaris
        /* kstats chain already opened by update_kstat (using *kc), verify everything went fine. */
        if (kc == NULL)
        {