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Code Issues Releases Activity

Fix vnodes starvation caused by DNLC (ZFS name cache):

Browse Source 
- Tune number of namecache entires better (based on desiredvnodes).
- Handle vfs_lowvnodes event by releasing requested number of name cache
  entries, but no less than 5%.

Reported by:	simokawa
This commit is contained in:
Pawel Jakub Dawidek 2007-04-13 08:42:01 +00:00
parent 6bc3ab2574
commit f0bc5ac3e1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=168683
2 changed files with 40 additions and 2 deletions
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21
sys/cddl/contrib/opensolaris/uts/common/fs/dnlc.c
View File

@ -53,6 +53,7 @@
#include <sys/taskq.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/eventhandler.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
@ -285,8 +286,10 @@ vnode_t negative_cache_vnode;
static ncache_t *dnlc_get(uchar_t namlen);
static ncache_t *dnlc_search(vnode_t *dp, char *name, uchar_t namlen, int hash);
static void do_dnlc_reduce_cache(void *);
static void dnlc_lowvnodes(void *arg __unused, int nvnodes);
static kstat_t *dnlc_ksp = NULL;
static eventhandler_tag dnlc_event_lowvnodes = NULL;
/*
* Initialize the directory cache.
@ -305,7 +308,7 @@ dnlc_init(void *arg __unused)
#if 0
dnlc_nentries_low_water = 4 * (v.v_proc + maxusers) + 320;
#else
dnlc_nentries_low_water = vm_kmem_size / 20480;
dnlc_nentries_low_water = (desiredvnodes * 49) / 100;
#endif
ncsize = dnlc_nentries_low_water +
(dnlc_nentries_low_water / dnlc_low_water_divisor);
@ -363,6 +366,9 @@ dnlc_init(void *arg __unused)
dnlc_ksp->ks_data = (void *) &ncs;
kstat_install(dnlc_ksp);
}
dnlc_event_lowvnodes = EVENTHANDLER_REGISTER(vfs_lowvnodes,
dnlc_lowvnodes, NULL, EVENTHANDLER_PRI_FIRST);
}
static void
@ -371,6 +377,9 @@ dnlc_fini(void *arg __unused)
nc_hash_t *hp;
int i;
if (dnlc_event_lowvnodes != NULL)
EVENTHANDLER_DEREGISTER(vfs_lowvnodes, dnlc_event_lowvnodes);
if (dnlc_ksp != NULL) {
kstat_delete(dnlc_ksp);
dnlc_ksp = NULL;
@ -820,5 +829,15 @@ do_dnlc_reduce_cache(void *reduce_percent)
dnlc_reduce_idle = 1;
}
static void
dnlc_lowvnodes(void *arg __unused, int nvnodes)
{
nvnodes /= ncsize_onepercent;
/* Free no less than 5%. */
nvnodes = nvnodes < 5 * ncsize_onepercent ? 5 * ncsize_onepercent : nvnodes;
dnlc_reduce_cache((void *)(intptr_t)nvnodes);
}
SYSINIT(dnlc, SI_SUB_DRIVERS, SI_ORDER_ANY, dnlc_init, NULL);
SYSUNINIT(dnlc, SI_SUB_DRIVERS, SI_ORDER_ANY, dnlc_fini, NULL);

21
sys/contrib/opensolaris/uts/common/fs/dnlc.c
View File

@ -53,6 +53,7 @@
#include <sys/taskq.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/eventhandler.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
@ -285,8 +286,10 @@ vnode_t negative_cache_vnode;
static ncache_t *dnlc_get(uchar_t namlen);
static ncache_t *dnlc_search(vnode_t *dp, char *name, uchar_t namlen, int hash);
static void do_dnlc_reduce_cache(void *);
static void dnlc_lowvnodes(void *arg __unused, int nvnodes);
static kstat_t *dnlc_ksp = NULL;
static eventhandler_tag dnlc_event_lowvnodes = NULL;
/*
* Initialize the directory cache.
@ -305,7 +308,7 @@ dnlc_init(void *arg __unused)
#if 0
dnlc_nentries_low_water = 4 * (v.v_proc + maxusers) + 320;
#else
dnlc_nentries_low_water = vm_kmem_size / 20480;
dnlc_nentries_low_water = (desiredvnodes * 49) / 100;
#endif
ncsize = dnlc_nentries_low_water +
(dnlc_nentries_low_water / dnlc_low_water_divisor);
@ -363,6 +366,9 @@ dnlc_init(void *arg __unused)
dnlc_ksp->ks_data = (void *) &ncs;
kstat_install(dnlc_ksp);
}
dnlc_event_lowvnodes = EVENTHANDLER_REGISTER(vfs_lowvnodes,
dnlc_lowvnodes, NULL, EVENTHANDLER_PRI_FIRST);
}
static void
@ -371,6 +377,9 @@ dnlc_fini(void *arg __unused)
nc_hash_t *hp;
int i;
if (dnlc_event_lowvnodes != NULL)
EVENTHANDLER_DEREGISTER(vfs_lowvnodes, dnlc_event_lowvnodes);
if (dnlc_ksp != NULL) {
kstat_delete(dnlc_ksp);
dnlc_ksp = NULL;
@ -820,5 +829,15 @@ do_dnlc_reduce_cache(void *reduce_percent)
dnlc_reduce_idle = 1;
}
static void
dnlc_lowvnodes(void *arg __unused, int nvnodes)
{
nvnodes /= ncsize_onepercent;
/* Free no less than 5%. */
nvnodes = nvnodes < 5 * ncsize_onepercent ? 5 * ncsize_onepercent : nvnodes;
dnlc_reduce_cache((void *)(intptr_t)nvnodes);
}
SYSINIT(dnlc, SI_SUB_DRIVERS, SI_ORDER_ANY, dnlc_init, NULL);
SYSUNINIT(dnlc, SI_SUB_DRIVERS, SI_ORDER_ANY, dnlc_fini, NULL);