Implement FreeBSD support for minimum ZFS ARC size

freebsd/Platform.c

@@ -227,6 +227,7 @@ double Platform_setCPUValues(Meter* this, unsigned int cpu) {
 
 void Platform_setMemoryValues(Meter* this) {
    const ProcessList* pl = this->pl;
+   const FreeBSDProcessList* fpl = (const FreeBSDProcessList*) pl;
 
    this->total = pl->totalMem;
    this->values[0] = pl->usedMem;
@@ -234,6 +235,16 @@ void Platform_setMemoryValues(Meter* this) {
    // this->values[2] = "shared memory, like tmpfs and shm"
    this->values[3] = pl->cachedMem;
    // this->values[4] = "available memory"
+
+   if (fpl->zfs.enabled) {
+      // ZFS does not shrink below the value of zfs_arc_min.
+      unsigned long long int shrinkableSize = 0;
+      if (fpl->zfs.size > fpl->zfs.min)
+         shrinkableSize = fpl->zfs.size - fpl->zfs.min;
+      this->values[0] -= shrinkableSize;
+      this->values[3] += shrinkableSize;
+      // this->values[4] += shrinkableSize;
+   }
 }
 
 void Platform_setSwapValues(Meter* this) {

generic/openzfs_sysctl.c

@@ -15,6 +15,7 @@ in the source distribution for its full text.
 
 
 static int MIB_kstat_zfs_misc_arcstats_size[5];
+static int MIB_kstat_zfs_misc_arcstats_c_min[5];
 static int MIB_kstat_zfs_misc_arcstats_c_max[5];
 static int MIB_kstat_zfs_misc_arcstats_mfu_size[5];
 static int MIB_kstat_zfs_misc_arcstats_mru_size[5];
@@ -35,6 +36,7 @@ void openzfs_sysctl_init(ZfsArcStats* stats) {
       len = 5;
       sysctlnametomib("kstat.zfs.misc.arcstats.size", MIB_kstat_zfs_misc_arcstats_size, &len);
 
+      sysctlnametomib("kstat.zfs.misc.arcstats.c_min", MIB_kstat_zfs_misc_arcstats_c_min, &len);
       sysctlnametomib("kstat.zfs.misc.arcstats.c_max", MIB_kstat_zfs_misc_arcstats_c_max, &len);
       sysctlnametomib("kstat.zfs.misc.arcstats.mfu_size", MIB_kstat_zfs_misc_arcstats_mfu_size, &len);
       sysctlnametomib("kstat.zfs.misc.arcstats.mru_size", MIB_kstat_zfs_misc_arcstats_mru_size, &len);
@@ -61,6 +63,10 @@ void openzfs_sysctl_updateArcStats(ZfsArcStats* stats) {
       sysctl(MIB_kstat_zfs_misc_arcstats_size, 5, &(stats->size), &len, NULL, 0);
       stats->size /= 1024;
 
+      len = sizeof(stats->min);
+      sysctl(MIB_kstat_zfs_misc_arcstats_c_min, 5, &(stats->min), &len, NULL, 0);
+      stats->min /= 1024;
+
       len = sizeof(stats->max);
       sysctl(MIB_kstat_zfs_misc_arcstats_c_max, 5, &(stats->max), &len, NULL, 0);
       stats->max /= 1024;