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iflib: Better control over queue core assignment

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By default, cores are now assigned to queues in a sequential
manner rather than all NICs starting at the first core. On a four-core
system with two NICs each using two queue pairs, the nic:queue -> core
mapping has changed from this:

0:0 -> 0, 0:1 -> 1
1:0 -> 0, 1:1 -> 1

To this:

0:0 -> 0, 0:1 -> 1
1:0 -> 2, 1:1 -> 3

Additionally, a device can now be configured to use separate cores for TX
and RX queues.

Two new tunables have been added, dev.X.Y.iflib.separate_txrx and
dev.X.Y.iflib.core_offset. If core_offset is set, the NIC is not part
of the auto-assigned sequence.

Reviewed by:	marius
MFC after:	2 weeks
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D20029
This commit is contained in:
Stephen Hurd 2019-04-25 21:24:56 +00:00
parent f0baac9e32
commit f154ece02e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=346708
2 changed files with 109 additions and 3 deletions
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10
share/man/man4/iflib.4
View File

@ -55,6 +55,16 @@ If zero, the number of TX queues is derived from the number of cores on the
socket connected to the controller.
.It Va disable_msix
Disables MSI-X interrupts for the device.
.It Va core_offset
Specifies a starting core offset to assign queues to.
If the value is unspecified or 65535, cores are assigned sequentially across
controllers.
.It Va separate_txrx
Requests that RX and TX queues not be paired on the same core.
If this is zero or not set, an RX and TX queue pair will be assigned to each
core.
When set to a non-zero value, TX queues are assigned to cores following the
last RX queue.
.El
.Pp
These

102
sys/net/iflib.c
View File

@ -189,6 +189,9 @@ struct iflib_ctx {
uint16_t ifc_sysctl_qs_eq_override;
uint16_t ifc_sysctl_rx_budget;
uint16_t ifc_sysctl_tx_abdicate;
uint16_t ifc_sysctl_core_offset;
#define CORE_OFFSET_UNSPECIFIED 0xffff
uint8_t ifc_sysctl_separate_txrx;
qidx_t ifc_sysctl_ntxds[8];
qidx_t ifc_sysctl_nrxds[8];
@ -723,6 +726,18 @@ static void iflib_free_intr_mem(if_ctx_t ctx);
static struct mbuf * iflib_fixup_rx(struct mbuf *m);
#endif
static SLIST_HEAD(cpu_offset_list, cpu_offset) cpu_offsets =
SLIST_HEAD_INITIALIZER(cpu_offsets);
struct cpu_offset {
SLIST_ENTRY(cpu_offset) entries;
cpuset_t set;
unsigned int refcount;
uint16_t offset;
};
static struct mtx cpu_offset_mtx;
MTX_SYSINIT(iflib_cpu_offset, &cpu_offset_mtx, "iflib_cpu_offset lock",
MTX_DEF);
NETDUMP_DEFINE(iflib);
#ifdef DEV_NETMAP
@ -4461,6 +4476,71 @@ iflib_rem_pfil(if_ctx_t ctx)
pfil_head_unregister(pfil);
}
static uint16_t
get_ctx_core_offset(if_ctx_t ctx)
{
if_softc_ctx_t scctx = &ctx->ifc_softc_ctx;
struct cpu_offset *op;
uint16_t qc;
uint16_t ret = ctx->ifc_sysctl_core_offset;
if (ret != CORE_OFFSET_UNSPECIFIED)
return (ret);
if (ctx->ifc_sysctl_separate_txrx)
qc = scctx->isc_ntxqsets + scctx->isc_nrxqsets;
else
qc = max(scctx->isc_ntxqsets, scctx->isc_nrxqsets);
mtx_lock(&cpu_offset_mtx);
SLIST_FOREACH(op, &cpu_offsets, entries) {
if (CPU_CMP(&ctx->ifc_cpus, &op->set) == 0) {
ret = op->offset;
op->offset += qc;
MPASS(op->refcount < UINT_MAX);
op->refcount++;
break;
}
}
if (ret == CORE_OFFSET_UNSPECIFIED) {
ret = 0;
op = malloc(sizeof(struct cpu_offset), M_IFLIB,
M_NOWAIT | M_ZERO);
if (op == NULL) {
device_printf(ctx->ifc_dev,
"allocation for cpu offset failed.\n");
} else {
op->offset = qc;
op->refcount = 1;
CPU_COPY(&ctx->ifc_cpus, &op->set);
SLIST_INSERT_HEAD(&cpu_offsets, op, entries);
}
}
mtx_unlock(&cpu_offset_mtx);
return (ret);
}
static void
unref_ctx_core_offset(if_ctx_t ctx)
{
struct cpu_offset *op, *top;
mtx_lock(&cpu_offset_mtx);
SLIST_FOREACH_SAFE(op, &cpu_offsets, entries, top) {
if (CPU_CMP(&ctx->ifc_cpus, &op->set) == 0) {
MPASS(op->refcount > 0);
op->refcount--;
if (op->refcount == 0) {
SLIST_REMOVE(&cpu_offsets, op, cpu_offset, entries);
free(op, M_IFLIB);
}
break;
}
}
mtx_unlock(&cpu_offset_mtx);
}
int
iflib_device_register(device_t dev, void *sc, if_shared_ctx_t sctx, if_ctx_t *ctxp)
{
@ -4612,6 +4692,11 @@ iflib_device_register(device_t dev, void *sc, if_shared_ctx_t sctx, if_ctx_t *ct
if ((err = iflib_qset_structures_setup(ctx)))
goto fail_queues;
/*
* Now that we know how many queues there are, get the core offset.
*/
ctx->ifc_sysctl_core_offset = get_ctx_core_offset(ctx);
/*
* Group taskqueues aren't properly set up until SMP is started,
* so we disable interrupts until we can handle them post
@ -5037,6 +5122,7 @@ iflib_device_deregister(if_ctx_t ctx)
iflib_rx_structures_free(ctx);
if (ctx->ifc_flags & IFC_SC_ALLOCATED)
free(ctx->ifc_softc, M_IFLIB);
unref_ctx_core_offset(ctx);
STATE_LOCK_DESTROY(ctx);
free(ctx, M_IFLIB);
return (0);
@ -5655,7 +5741,7 @@ find_child_with_core(int cpu, struct cpu_group *grp)
* Find the nth "close" core to the specified core
* "close" is defined as the deepest level that shares
* at least an L2 cache. With threads, this will be
* threads on the same core. If the sahred cache is L3
* threads on the same core. If the shared cache is L3
* or higher, simply returns the same core.
*/
static int
@ -5739,10 +5825,13 @@ iflib_irq_set_affinity(if_ctx_t ctx, if_irq_t irq, iflib_intr_type_t type,
const char *name)
{
device_t dev;
int err, cpuid, tid;
int co, cpuid, err, tid;
dev = ctx->ifc_dev;
cpuid = find_nth(ctx, qid);
co = ctx->ifc_sysctl_core_offset;
if (ctx->ifc_sysctl_separate_txrx && type == IFLIB_INTR_TX)
co += ctx->ifc_softc_ctx.isc_nrxqsets;
cpuid = find_nth(ctx, qid + co);
tid = get_core_offset(ctx, type, qid);
MPASS(tid >= 0);
cpuid = find_close_core(cpuid, tid);
@ -6344,6 +6433,13 @@ iflib_add_device_sysctl_pre(if_ctx_t ctx)
SYSCTL_ADD_U16(ctx_list, oid_list, OID_AUTO, "tx_abdicate",
CTLFLAG_RWTUN, &ctx->ifc_sysctl_tx_abdicate, 0,
"cause tx to abdicate instead of running to completion");
ctx->ifc_sysctl_core_offset = CORE_OFFSET_UNSPECIFIED;
SYSCTL_ADD_U16(ctx_list, oid_list, OID_AUTO, "core_offset",
CTLFLAG_RDTUN, &ctx->ifc_sysctl_core_offset, 0,
"offset to start using cores at");
SYSCTL_ADD_U8(ctx_list, oid_list, OID_AUTO, "separate_txrx",
CTLFLAG_RDTUN, &ctx->ifc_sysctl_separate_txrx, 0,
"use separate cores for TX and RX");
/* XXX change for per-queue sizes */
SYSCTL_ADD_PROC(ctx_list, oid_list, OID_AUTO, "override_ntxds",