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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
#include <sys/zfs_context.h>
#include <sys/spa_impl.h>
/*
* Keeps stats on last N reads per spa_t, disabled by default.
*/
int zfs_read_history = 0;
/*
* Include cache hits in history, disabled by default.
*/
int zfs_read_history_hits = 0;
/*
* ==========================================================================
* SPA Read History Routines
* ==========================================================================
*/
/*
* Read statistics - Information exported regarding each arc_read call
*/
typedef struct spa_read_history {
uint64_t uid; /* unique identifier */
hrtime_t start; /* time read completed */
uint64_t objset; /* read from this objset */
uint64_t object; /* read of this object number */
uint64_t level; /* block's indirection level */
uint64_t blkid; /* read of this block id */
char origin[24]; /* read originated from here */
uint32_t aflags; /* ARC flags (cached, prefetch, etc.) */
pid_t pid; /* PID of task doing read */
char comm[16]; /* process name of task doing read */
list_node_t srh_link;
} spa_read_history_t;
static int
spa_read_history_headers(char *buf, size_t size)
{
size = snprintf(buf, size - 1, "%-8s %-16s %-8s %-8s %-8s %-8s %-8s "
"%-24s %-8s %-16s\n", "UID", "start", "objset", "object",
"level", "blkid", "aflags", "origin", "pid", "process");
buf[size] = '\0';
return (0);
}
static int
spa_read_history_data(char *buf, size_t size, void *data)
{
spa_read_history_t *srh = (spa_read_history_t *)data;
size = snprintf(buf, size - 1, "%-8llu %-16llu 0x%-6llx "
"%-8lli %-8lli %-8lli 0x%-6x %-24s %-8i %-16s\n",
(u_longlong_t)srh->uid, srh->start,
(longlong_t)srh->objset, (longlong_t)srh->object,
(longlong_t)srh->level, (longlong_t)srh->blkid,
srh->aflags, srh->origin, srh->pid, srh->comm);
buf[size] = '\0';
return (0);
}
/*
* Calculate the address for the next spa_stats_history_t entry. The
* ssh->lock will be held until ksp->ks_ndata entries are processed.
*/
static void *
spa_read_history_addr(kstat_t *ksp, loff_t n)
{
spa_t *spa = ksp->ks_private;
spa_stats_history_t *ssh = &spa->spa_stats.read_history;
ASSERT(MUTEX_HELD(&ssh->lock));
if (n == 0)
ssh->private = list_tail(&ssh->list);
else if (ssh->private)
ssh->private = list_prev(&ssh->list, ssh->private);
return (ssh->private);
}
/*
* When the kstat is written discard all spa_read_history_t entires. The
* ssh->lock will be held until ksp->ks_ndata entries are processed.
*/
static int
spa_read_history_update(kstat_t *ksp, int rw)
{
spa_t *spa = ksp->ks_private;
spa_stats_history_t *ssh = &spa->spa_stats.read_history;
if (rw == KSTAT_WRITE) {
spa_read_history_t *srh;
while ((srh = list_remove_head(&ssh->list))) {
ssh->size--;
kmem_free(srh, sizeof(spa_read_history_t));
}
ASSERT3U(ssh->size, ==, 0);
}
ksp->ks_ndata = ssh->size;
ksp->ks_data_size = ssh->size * sizeof(spa_read_history_t);
return (0);
}
static void
spa_read_history_init(spa_t *spa)
{
spa_stats_history_t *ssh = &spa->spa_stats.read_history;
char name[KSTAT_STRLEN];
kstat_t *ksp;
mutex_init(&ssh->lock, NULL, MUTEX_DEFAULT, NULL);
list_create(&ssh->list, sizeof (spa_read_history_t),
offsetof(spa_read_history_t, srh_link));
ssh->count = 0;
ssh->size = 0;
ssh->private = NULL;
(void) snprintf(name, KSTAT_STRLEN, "zfs/%s", spa_name(spa));
name[KSTAT_STRLEN-1] = '\0';
ksp = kstat_create(name, 0, "reads", "misc",
KSTAT_TYPE_RAW, 0, KSTAT_FLAG_VIRTUAL);
ssh->kstat = ksp;
if (ksp) {
ksp->ks_lock = &ssh->lock;
ksp->ks_data = NULL;
ksp->ks_private = spa;
ksp->ks_update = spa_read_history_update;
kstat_set_raw_ops(ksp, spa_read_history_headers,
spa_read_history_data, spa_read_history_addr);
kstat_install(ksp);
}
}
static void
spa_read_history_destroy(spa_t *spa)
{
spa_stats_history_t *ssh = &spa->spa_stats.read_history;
spa_read_history_t *srh;
kstat_t *ksp;
ksp = ssh->kstat;
if (ksp)
kstat_delete(ksp);
mutex_enter(&ssh->lock);
while ((srh = list_remove_head(&ssh->list))) {
ssh->size--;
kmem_free(srh, sizeof(spa_read_history_t));
}
ASSERT3U(ssh->size, ==, 0);
list_destroy(&ssh->list);
mutex_exit(&ssh->lock);
mutex_destroy(&ssh->lock);
}
void
spa_read_history_add(spa_t *spa, const zbookmark_t *zb, uint32_t aflags)
{
spa_stats_history_t *ssh = &spa->spa_stats.read_history;
spa_read_history_t *srh, *rm;
ASSERT3P(spa, !=, NULL);
ASSERT3P(zb, !=, NULL);
if (zfs_read_history == 0 && ssh->size == 0)
return;
if (zfs_read_history_hits == 0 && (aflags & ARC_CACHED))
return;
srh = kmem_zalloc(sizeof(spa_read_history_t), KM_PUSHPAGE);
strlcpy(srh->origin, zb->zb_func, sizeof(srh->origin));
strlcpy(srh->comm, getcomm(), sizeof(srh->comm));
srh->start = gethrtime();
srh->objset = zb->zb_objset;
srh->object = zb->zb_object;
srh->level = zb->zb_level;
srh->blkid = zb->zb_blkid;
srh->aflags = aflags;
srh->pid = getpid();
mutex_enter(&ssh->lock);
srh->uid = ssh->count++;
list_insert_head(&ssh->list, srh);
ssh->size++;
while (ssh->size > zfs_read_history) {
ssh->size--;
rm = list_remove_tail(&ssh->list);
kmem_free(rm, sizeof(spa_read_history_t));
}
mutex_exit(&ssh->lock);
}
void
spa_stats_init(spa_t *spa)
{
spa_read_history_init(spa);
}
void
spa_stats_destroy(spa_t *spa)
{
spa_read_history_destroy(spa);
}
#if defined(_KERNEL) && defined(HAVE_SPL)
module_param(zfs_read_history, int, 0644);
MODULE_PARM_DESC(zfs_read_history, "Historic statistics for the last N reads");
module_param(zfs_read_history_hits, int, 0644);
MODULE_PARM_DESC(zfs_read_history_hits, "Include cache hits in read history");
#endif
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