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ZIO: Set minimum number of free issue threads to 32

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Free issue threads might block waiting for synchronous DDT, BRT or
GANG header reads. So unlike other taskqs using ZTI_SCALE to scale
with number of CPUs, here we also need some amount of threads to
potentially saturate pool reads.  I am not sure we always want the
96 threads we had before ZTI_SCALE introduction at #11966 on small
systems, but lets make it at least 32.

While here, make free taskqs configurable, similar to read and
write ones.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Rob Norris <robn@despairlabs.com>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes #17903
This commit is contained in:
Alexander Motin 2025-11-08 14:41:53 -05:00 committed by Brian Behlendorf
parent 583db40030
commit aaf374bd40
3 changed files with 127 additions and 18 deletions
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3
include/os/freebsd/spl/sys/mod.h
View File

@ -104,6 +104,9 @@
#define spa_taskq_write_param_set_args(var) \
CTLTYPE_STRING, NULL, 0, spa_taskq_write_param, "A"
#define spa_taskq_free_param_set_args(var) \
CTLTYPE_STRING, NULL, 0, spa_taskq_free_param, "A"
#define fletcher_4_param_set_args(var) \
CTLTYPE_STRING, NULL, 0, fletcher_4_param, "A"

38
man/man4/zfs.4
View File

@ -2660,12 +2660,50 @@ Set value only applies to pools imported/created after that.
Set the queue and thread configuration for the IO read queues.
This is an advanced debugging parameter.
Don't change this unless you understand what it does.
Each of the four values corresponds to the issue, issue high-priority,
interrupt, and interrupt high-priority queues.
Valid values are
.Sy fixed,N,M
(M queues with N threads each),
.Sy scale[,MIN]
(scale with CPUs, minimum MIN total threads),
.Sy sync ,
and
.Sy null .
Set values only apply to pools imported/created after that.
.
.It Sy zio_taskq_write Ns = Ns Sy sync null scale null Pq charp
Set the queue and thread configuration for the IO write queues.
This is an advanced debugging parameter.
Don't change this unless you understand what it does.
Each of the four values corresponds to the issue, issue high-priority,
interrupt, and interrupt high-priority queues.
Valid values are
.Sy fixed,N,M
(M queues with N threads each),
.Sy scale[,MIN]
(scale with CPUs, minimum MIN total threads),
.Sy sync ,
and
.Sy null .
Set values only apply to pools imported/created after that.
.
.It Sy zio_taskq_free Ns = Ns Sy scale,32 null null null Pq charp
Set the queue and thread configuration for the IO free queues.
This is an advanced debugging parameter.
Don't change this unless you understand what it does.
Each of the four values corresponds to the issue, issue high-priority,
interrupt, and interrupt high-priority queues.
Valid values are
.Sy fixed,N,M
(M queues with N threads each),
.Sy scale[,MIN]
(scale with CPUs, minimum MIN total threads),
.Sy sync ,
and
.Sy null .
The default uses a minimum of 32 threads to improve parallelism for
DDT and BRT metadata operations during frees.
Set values only apply to pools imported/created after that.
.
.It Sy zvol_inhibit_dev Ns = Ns Sy 0 Ns | Ns 1 Pq uint

104
module/zfs/spa.c
View File

@ -141,7 +141,7 @@ typedef enum zti_modes {
#define ZTI_P(n, q) { ZTI_MODE_FIXED, (n), (q) }
#define ZTI_PCT(n) { ZTI_MODE_ONLINE_PERCENT, (n), 1 }
#define ZTI_SCALE { ZTI_MODE_SCALE, 0, 1 }
#define ZTI_SCALE(min) { ZTI_MODE_SCALE, (min), 1 }
#define ZTI_SYNC { ZTI_MODE_SYNC, 0, 1 }
#define ZTI_NULL { ZTI_MODE_NULL, 0, 0 }
@ -180,13 +180,13 @@ static const char *const zio_taskq_types[ZIO_TASKQ_TYPES] = {
static zio_taskq_info_t zio_taskqs[ZIO_TYPES][ZIO_TASKQ_TYPES] = {
/* ISSUE ISSUE_HIGH INTR INTR_HIGH */
{ ZTI_ONE, ZTI_NULL, ZTI_ONE, ZTI_NULL }, /* NULL */
{ ZTI_N(8), ZTI_NULL, ZTI_SCALE, ZTI_NULL }, /* READ */
{ ZTI_N(8), ZTI_NULL, ZTI_SCALE(0), ZTI_NULL }, /* READ */
#ifdef illumos
{ ZTI_SYNC, ZTI_N(5), ZTI_SCALE, ZTI_N(5) }, /* WRITE */
{ ZTI_SYNC, ZTI_N(5), ZTI_SCALE(0), ZTI_N(5) }, /* WRITE */
#else
{ ZTI_SYNC, ZTI_NULL, ZTI_SCALE, ZTI_NULL }, /* WRITE */
{ ZTI_SYNC, ZTI_NULL, ZTI_SCALE(0), ZTI_NULL }, /* WRITE */
#endif
{ ZTI_SCALE, ZTI_NULL, ZTI_ONE, ZTI_NULL }, /* FREE */
{ ZTI_SCALE(32), ZTI_NULL, ZTI_ONE, ZTI_NULL }, /* FREE */
{ ZTI_ONE, ZTI_NULL, ZTI_ONE, ZTI_NULL }, /* CLAIM */
{ ZTI_ONE, ZTI_NULL, ZTI_ONE, ZTI_NULL }, /* FLUSH */
{ ZTI_N(4), ZTI_NULL, ZTI_ONE, ZTI_NULL }, /* TRIM */
@ -1170,7 +1170,7 @@ spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
uint_t value = ztip->zti_value;
uint_t count = ztip->zti_count;
spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
uint_t cpus, flags = TASKQ_DYNAMIC;
uint_t cpus, threads, flags = TASKQ_DYNAMIC;
switch (mode) {
case ZTI_MODE_FIXED:
@ -1183,8 +1183,8 @@ spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
* Create one wr_iss taskq for every 'zio_taskq_write_tpq' CPUs,
* not to exceed the number of spa allocators, and align to it.
*/
cpus = MAX(1, boot_ncpus * zio_taskq_batch_pct / 100);
count = MAX(1, cpus / MAX(1, zio_taskq_write_tpq));
threads = MAX(1, boot_ncpus * zio_taskq_batch_pct / 100);
count = MAX(1, threads / MAX(1, zio_taskq_write_tpq));
count = MAX(count, (zio_taskq_batch_pct + 99) / 100);
count = MIN(count, spa->spa_alloc_count);
while (spa->spa_alloc_count % count != 0 &&
@ -1201,14 +1201,14 @@ spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
break;
case ZTI_MODE_SCALE:
flags |= TASKQ_THREADS_CPU_PCT;
/*
* We want more taskqs to reduce lock contention, but we want
* less for better request ordering and CPU utilization.
*/
cpus = MAX(1, boot_ncpus * zio_taskq_batch_pct / 100);
threads = MAX(1, boot_ncpus * zio_taskq_batch_pct / 100);
threads = MAX(threads, value);
if (zio_taskq_batch_tpq > 0) {
count = MAX(1, (cpus + zio_taskq_batch_tpq / 2) /
count = MAX(1, (threads + zio_taskq_batch_tpq / 2) /
zio_taskq_batch_tpq);
} else {
/*
@ -1228,13 +1228,23 @@ spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
* 128 10 8% 10 100
* 256 14 6% 15 210
*/
count = 1 + cpus / 6;
cpus = MIN(threads, boot_ncpus);
count = 1 + threads / 6;
while (count * count > cpus)
count--;
}
/* Limit each taskq within 100% to not trigger assertion. */
count = MAX(count, (zio_taskq_batch_pct + 99) / 100);
value = (zio_taskq_batch_pct + count / 2) / count;
/*
* Try to represent the number of threads per taskq as percent
* of online CPUs to allow scaling with later online/offline.
* Fall back to absolute numbers if can't.
*/
value = (threads * 100 + boot_ncpus * count / 2) /
(boot_ncpus * count);
if (value < 5 || value > 100)
value = MAX(1, (threads + count / 2) / count);
else
flags |= TASKQ_THREADS_CPU_PCT;
break;
case ZTI_MODE_NULL:
@ -1433,8 +1443,30 @@ spa_taskq_param_set(zio_type_t t, char *cfg)
break;
}
/*
* SCALE is optionally parameterised by minimum number of
* threads.
*/
case ZTI_MODE_SCALE: {
const zio_taskq_info_t zti = ZTI_SCALE;
unsigned long long mint = 0;
if (c != NULL && *c != '\0') {
/* Need a number */
if (!(isdigit(*c)))
break;
tok = c;
/* Take digits */
err = ddi_strtoull(tok, &tok, 10, &mint);
/* Must succeed, and moved forward */
if (err != 0 || tok == c || *tok != '\0')
break;
/* Sanity check */
if (mint >= 16384)
break;
}
const zio_taskq_info_t zti = ZTI_SCALE(mint);
row[q] = zti;
break;
}
@ -1501,6 +1533,9 @@ spa_taskq_param_get(zio_type_t t, char *buf, boolean_t add_newline)
pos += sprintf(&buf[pos], "%s%s,%u,%u", sep,
modes[zti->zti_mode], zti->zti_count,
zti->zti_value);
else if (zti->zti_mode == ZTI_MODE_SCALE && zti->zti_value > 0)
pos += sprintf(&buf[pos], "%s%s,%u", sep,
modes[zti->zti_mode], zti->zti_value);
else
pos += sprintf(&buf[pos], "%s%s", sep,
modes[zti->zti_mode]);
@ -1520,9 +1555,10 @@ spa_taskq_read_param_set(const char *val, zfs_kernel_param_t *kp)
{
char *cfg = kmem_strdup(val);
int err = spa_taskq_param_set(ZIO_TYPE_READ, cfg);
kmem_free(cfg, strlen(val)+1);
kmem_strfree(cfg);
return (-err);
}
static int
spa_taskq_read_param_get(char *buf, zfs_kernel_param_t *kp)
{
@ -1534,14 +1570,30 @@ spa_taskq_write_param_set(const char *val, zfs_kernel_param_t *kp)
{
char *cfg = kmem_strdup(val);
int err = spa_taskq_param_set(ZIO_TYPE_WRITE, cfg);
kmem_free(cfg, strlen(val)+1);
kmem_strfree(cfg);
return (-err);
}
static int
spa_taskq_write_param_get(char *buf, zfs_kernel_param_t *kp)
{
return (spa_taskq_param_get(ZIO_TYPE_WRITE, buf, TRUE));
}
static int
spa_taskq_free_param_set(const char *val, zfs_kernel_param_t *kp)
{
char *cfg = kmem_strdup(val);
int err = spa_taskq_param_set(ZIO_TYPE_FREE, cfg);
kmem_strfree(cfg);
return (-err);
}
static int
spa_taskq_free_param_get(char *buf, zfs_kernel_param_t *kp)
{
return (spa_taskq_param_get(ZIO_TYPE_FREE, buf, TRUE));
}
#else
/*
* On FreeBSD load-time parameters can be set up before malloc() is available,
@ -1574,6 +1626,19 @@ spa_taskq_write_param(ZFS_MODULE_PARAM_ARGS)
return (err);
return (spa_taskq_param_set(ZIO_TYPE_WRITE, buf));
}
static int
spa_taskq_free_param(ZFS_MODULE_PARAM_ARGS)
{
char buf[SPA_TASKQ_PARAM_MAX];
int err;
(void) spa_taskq_param_get(ZIO_TYPE_FREE, buf, FALSE);
err = sysctl_handle_string(oidp, buf, sizeof (buf), req);
if (err || req->newptr == NULL)
return (err);
return (spa_taskq_param_set(ZIO_TYPE_FREE, buf));
}
#endif
#endif /* _KERNEL */
@ -11273,6 +11338,9 @@ ZFS_MODULE_VIRTUAL_PARAM_CALL(zfs_zio, zio_, taskq_read,
ZFS_MODULE_VIRTUAL_PARAM_CALL(zfs_zio, zio_, taskq_write,
spa_taskq_write_param_set, spa_taskq_write_param_get, ZMOD_RW,
"Configure IO queues for write IO");
ZFS_MODULE_VIRTUAL_PARAM_CALL(zfs_zio, zio_, taskq_free,
spa_taskq_free_param_set, spa_taskq_free_param_get, ZMOD_RW,
"Configure IO queues for free IO");
#endif
ZFS_MODULE_PARAM(zfs_zio, zio_, taskq_write_tpq, UINT, ZMOD_RW,