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Make it possible to disable NUMA support with a tunable.

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This provides a chicken switch for anyone negatively impacted by
enabling NUMA in the amd64 GENERIC kernel configuration.  With
NUMA disabled at boot-time, information about the NUMA topology
is not exposed to the rest of the kernel, and all of physical
memory is viewed as coming from a single domain.

This method still has some performance overhead relative to disabling
NUMA support at compile time.

PR:		231460
Reviewed by:	alc, gallatin, kib
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17439
This commit is contained in:
Mark Johnston 2018-10-22 20:13:51 +00:00
parent a7d9306a40
commit b61f314290
5 changed files with 49 additions and 25 deletions
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30
share/man/man4/numa.4
View File

@ -24,18 +24,16 @@
.\"
.\" $FreeBSD$
.\"
.Dd July 10, 2018
.Dd October 22, 2018
.Dt NUMA 4
.Os
.Sh NAME
.Nm NUMA
.Nd Non-Uniform Memory Access
.Sh SYNOPSIS
.Cd options SMP
.Cd options MAXMEMDOM=16
.Cd options MAXMEMDOM
.Cd options NUMA
.Pp
.In sys/cpuset.h
.In sys/bus.h
.Sh DESCRIPTION
Non-Uniform Memory Access is a computer architecture design which
involves unequal costs between processors, memory and IO devices
@ -47,14 +45,26 @@ architecture, the latency to access specific memory or IO devices
depends upon which processor the memory or device is attached to.
Accessing memory local to a processor is faster than accessing memory
that is connected to one of the other processors.
.Fx
implements NUMA-aware memory allocation policies.
By default it attempts to ensure that allocations are balanced across
each domain.
Users may override the default domain selection policy using
.Xr cpuset 1 .
.Pp
.Nm
is enabled when the
support is enabled when the
.Cd NUMA
option is used in a kernel configuration
file and the
option is specified in the kernel configuration file.
Each platform defines the
.Cd MAXMEMDOM
option is set to a value greater than 1.
constant, which specifies the maximum number of supported NUMA domains.
This constant may be specified in the kernel configuration file.
.Nm
support can be disabled at boot time by setting the
.Va vm.numa.disabled
tunable to 1.
Other values for this tunable are currently ignored.
.Pp
Thread and process
.Nm
@ -128,7 +138,7 @@ tool first appeared in
.Fx 11.0
and were removed in
.Fx 12.0 .
Current implementation appeared in
The current implementation appeared in
.Fx 12.0 .
.Pp
.Sh AUTHORS

11
sys/arm64/arm64/mp_machdep.c
View File

@ -576,11 +576,12 @@ cpu_init_fdt(u_int id, phandle_t node, u_int addr_size, pcell_t *reg)
return (FALSE);
/* Try to read the numa node of this cpu */
if (OF_getencprop(node, "numa-node-id", &domain, sizeof(domain)) > 0) {
__pcpu[id].pc_domain = domain;
if (domain < MAXMEMDOM)
CPU_SET(id, &cpuset_domain[domain]);
}
if (vm_ndomains == 1 ||
OF_getencprop(node, "numa-node-id", &domain, sizeof(domain)) <= 0)
domain = 0;
__pcpu[id].pc_domain = domain;
if (domain < MAXMEMDOM)
CPU_SET(id, &cpuset_domain[domain]);
return (TRUE);
}

6
sys/kern/kern_cpuset.c
View File

@ -458,6 +458,12 @@ _domainset_create(struct domainset *domain, struct domainlist *freelist)
struct domainset *ndomain;
int i, j, max;
KASSERT(domain->ds_cnt <= vm_ndomains,
("invalid domain count in domainset %p", domain));
KASSERT(domain->ds_policy != DOMAINSET_POLICY_PREFER ||
domain->ds_prefer < vm_ndomains,
("invalid preferred domain in domains %p", domain));
mtx_lock_spin(&cpuset_lock);
LIST_FOREACH(ndomain, &cpuset_domains, ds_link)
if (domainset_equal(ndomain, domain))

19
sys/vm/vm_phys.c
View File

@ -597,11 +597,22 @@ vm_phys_register_domains(int ndomains, struct mem_affinity *affinity,
int *locality)
{
#ifdef NUMA
int i;
int d, i;
vm_ndomains = ndomains;
mem_affinity = affinity;
mem_locality = locality;
/*
* For now the only override value that we support is 1, which
* effectively disables NUMA-awareness in the allocators.
*/
d = 0;
TUNABLE_INT_FETCH("vm.numa.disabled", &d);
if (d)
ndomains = 1;
if (ndomains > 1) {
vm_ndomains = ndomains;
mem_affinity = affinity;
mem_locality = locality;
}
for (i = 0; i < vm_ndomains; i++)
DOMAINSET_SET(i, &all_domains);

8
sys/x86/acpica/srat.c
View File

@ -535,11 +535,7 @@ srat_set_cpus(void *dummy)
if (!cpu->enabled)
panic("SRAT: CPU with APIC ID %u is not known",
pc->pc_apic_id);
#ifdef NUMA
pc->pc_domain = cpu->domain;
#else
pc->pc_domain = 0;
#endif
pc->pc_domain = vm_ndomains > 1 ? cpu->domain : 0;
CPU_SET(i, &cpuset_domain[pc->pc_domain]);
if (bootverbose)
printf("SRAT: CPU %u has memory domain %d\n", i,
@ -564,7 +560,7 @@ acpi_map_pxm_to_vm_domainid(int pxm)
for (i = 0; i < ndomain; i++) {
if (domain_pxm[i] == pxm)
return (i);
return (vm_ndomains > 1 ? i : 0);
}
return (-1);