svn commit: r342771 - in head: share/man/man4 sys/kern sys/powerpc/powernv sys/powerpc/powerpc sys/powerpc/ps3 sys/powerpc/pseries sys/sys sys/x86/x86
Rodney W. Grimes
freebsd at pdx.rh.CN85.dnsmgr.net
Fri Jan 4 19:07:31 UTC 2019
> Author: cem
> Date: Fri Jan 4 18:31:17 2019
> New Revision: 342771
> URL: https://svnweb.freebsd.org/changeset/base/342771
>
> Log:
> Expose threads-per-core and physical core count information
>
> With new sysctls (to the best of our ability do detect them). Restructured
> smp.4 slightly for clarity (keep relevant stuff closer to the top) while
> documenting.
>
> Reviewed by: markj, jhibbits (ppc parts)
> MFC after: 3 days
> Sponsored by: Dell EMC Isilon
> Differential Revision: https://reviews.freebsd.org/D18322
>
> Modified:
> head/share/man/man4/smp.4
> head/sys/kern/subr_smp.c
> head/sys/powerpc/powernv/platform_powernv.c
> head/sys/powerpc/powerpc/mp_machdep.c
> head/sys/powerpc/ps3/platform_ps3.c
> head/sys/powerpc/pseries/platform_chrp.c
> head/sys/sys/smp.h
> head/sys/x86/x86/mp_x86.c
Can you please alter this to match how topology is expressed
by most tools,
Sockets,
Cores per socket,
Threads per core.
ncpu = S * C * T
This matches how bhyve, qemu, kvm and others express
this information.
Thanks,
Rod
> Modified: head/share/man/man4/smp.4
> ==============================================================================
> --- head/share/man/man4/smp.4 Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/share/man/man4/smp.4 Fri Jan 4 18:31:17 2019 (r342771)
> @@ -23,7 +23,7 @@
> .\"
> .\" $FreeBSD$
> .\"
> -.Dd January 6, 2018
> +.Dd January 4, 2019
> .Dt SMP 4
> .Os
> .Sh NAME
> @@ -35,27 +35,6 @@
> The
> .Nm
> kernel implements symmetric multi-processor support.
> -.Sh COMPATIBILITY
> -Support for multi-processor systems is present for all Tier-1
> -architectures on
> -.Fx .
> -Currently, this includes amd64, i386 and sparc64.
> -Support is enabled using
> -.Cd options SMP .
> -It is permissible to use the SMP kernel configuration on non-SMP equipped
> -motherboards.
> -.Sh I386 NOTES
> -For i386 systems, the
> -.Nm
> -kernel supports motherboards that follow the Intel MP specification,
> -version 1.4.
> -In addition to
> -.Cd options SMP ,
> -i386 also requires
> -.Cd device apic .
> -The
> -.Xr mptable 1
> -command may be used to view the status of multi-processor support.
> .Pp
> .Nm
> support can be disabled by setting the loader tunable
> @@ -66,6 +45,13 @@ The number of CPUs detected by the system is available
> the read-only sysctl variable
> .Va hw.ncpu .
> .Pp
> +The number of online threads per CPU core is available in the read-only sysctl
> +variable
> +.Va kern.smp.threads_per_core .
> +The number of physical CPU cores detected by the system is available in the
> +read-only sysctl variable
> +.Va kern.smp.cores .
> +.Pp
> .Fx
> allows specific CPUs on a multi-processor system to be disabled.
> This can be done using the
> @@ -74,6 +60,12 @@ tunable, where X is the APIC ID of a CPU.
> Setting this tunable to 1 will result in the corresponding CPU being
> disabled.
> .Pp
> +.Fx
> +supports simultaneous multithreading on x86 and powerpc platforms.
> +On x86, the logical CPUs can be disabled by setting the
> +.Va machdep.hyperthreading_allowed
> +tunable to zero.
> +.Pp
> The
> .Xr sched_ule 4
> scheduler implements CPU topology detection and adjusts the scheduling
> @@ -122,13 +114,26 @@ two quad-core processors is:
> .Pp
> This information is used internally by the kernel to schedule related
> tasks on CPUs that are closely grouped together.
> -.Pp
> -.Fx
> -supports hyperthreading on Intel CPU's on the i386 and AMD64 platforms.
> -Because using logical CPUs can cause performance penalties under certain loads,
> -the logical CPUs can be disabled by setting the
> -.Va machdep.hyperthreading_allowed
> -tunable to zero.
> +.Sh COMPATIBILITY
> +Support for multi-processor systems is present for all Tier-1 and Tier-2
> +architectures on
> +.Fx .
> +Currently, this includes x86, powerpc, arm, and sparc64.
> +Support is enabled using
> +.Cd options SMP .
> +It is permissible to use the SMP kernel configuration on non-SMP hardware.
> +.Sh I386 NOTES
> +For i386 systems, the
> +.Nm
> +kernel supports motherboards that follow the Intel MP specification,
> +version 1.4.
> +In addition to
> +.Cd options SMP ,
> +i386 also requires
> +.Cd device apic .
> +The
> +.Xr mptable 1
> +command may be used to view the status of multi-processor support.
> .Sh SEE ALSO
> .Xr cpuset 1 ,
> .Xr mptable 1 ,
> @@ -166,3 +171,20 @@ in
> also introduced support for SMP on the sparc64 architecture.
> .Sh AUTHORS
> .An Steve Passe Aq Mt fsmp at FreeBSD.org
> +.Sh CAVEATS
> +The
> +.Va kern.smp.threads_per_core
> +and
> +.Va kern.smp.cores
> +sysctl variables are provided as a best-effort guess.
> +If an architecture or platform adds SMT and
> +.Fx
> +has not yet implemented detection, the reported values may be inaccurate.
> +In this case,
> +.Va kern.smp.threads_per_core
> +will report
> +.Dv 1
> +and
> +.Va kern.smp.cores
> +will report the same value as
> +.Va hw.ncpu .
>
> Modified: head/sys/kern/subr_smp.c
> ==============================================================================
> --- head/sys/kern/subr_smp.c Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/sys/kern/subr_smp.c Fri Jan 4 18:31:17 2019 (r342771)
> @@ -98,6 +98,14 @@ int smp_cpus = 1; /* how many cpu's running */
> SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD|CTLFLAG_CAPRD, &smp_cpus, 0,
> "Number of CPUs online");
>
> +int smp_threads_per_core = 1; /* how many SMT threads are running per core */
> +SYSCTL_INT(_kern_smp, OID_AUTO, threads_per_core, CTLFLAG_RD|CTLFLAG_CAPRD,
> + &smp_threads_per_core, 0, "Number of SMT threads online per core");
> +
> +int mp_ncores = -1; /* how many physical cores running */
> +SYSCTL_INT(_kern_smp, OID_AUTO, cores, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_ncores, 0,
> + "Number of CPUs online");
> +
> int smp_topology = 0; /* Which topology we're using. */
> SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RDTUN, &smp_topology, 0,
> "Topology override setting; 0 is default provided by hardware.");
> @@ -154,6 +162,7 @@ mp_start(void *dummy)
>
> /* Probe for MP hardware. */
> if (smp_disabled != 0 || cpu_mp_probe() == 0) {
> + mp_ncores = 1;
> mp_ncpus = 1;
> CPU_SETOF(PCPU_GET(cpuid), &all_cpus);
> return;
> @@ -162,6 +171,11 @@ mp_start(void *dummy)
> cpu_mp_start();
> printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n",
> mp_ncpus);
> +
> + /* Provide a default for most architectures that don't have SMT/HTT. */
> + if (mp_ncores < 0)
> + mp_ncores = mp_ncpus;
> +
> cpu_mp_announce();
> }
> SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL);
> @@ -823,6 +837,7 @@ static void
> mp_setvariables_for_up(void *dummy)
> {
> mp_ncpus = 1;
> + mp_ncores = 1;
> mp_maxid = PCPU_GET(cpuid);
> CPU_SETOF(mp_maxid, &all_cpus);
> KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero"));
>
> Modified: head/sys/powerpc/powernv/platform_powernv.c
> ==============================================================================
> --- head/sys/powerpc/powernv/platform_powernv.c Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/sys/powerpc/powernv/platform_powernv.c Fri Jan 4 18:31:17 2019 (r342771)
> @@ -435,12 +435,16 @@ powernv_smp_topo(platform_t plat)
> break;
> }
>
> + smp_threads_per_core = nthreads;
> +
> if (mp_ncpus % nthreads != 0) {
> printf("WARNING: Irregular SMP topology. Performance may be "
> "suboptimal (%d threads, %d on first core)\n",
> mp_ncpus, nthreads);
> return (smp_topo_none());
> }
> +
> + mp_ncores = mp_ncpus / nthreads;
>
> /* Don't do anything fancier for non-threaded SMP */
> if (nthreads == 1)
>
> Modified: head/sys/powerpc/powerpc/mp_machdep.c
> ==============================================================================
> --- head/sys/powerpc/powerpc/mp_machdep.c Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/sys/powerpc/powerpc/mp_machdep.c Fri Jan 4 18:31:17 2019 (r342771)
> @@ -186,6 +186,11 @@ cpu_mp_start(void)
> next:
> error = platform_smp_next_cpu(&cpu);
> }
> +
> +#ifdef SMP
> + /* Probe mp_ncores and smp_threads_per_core as a side effect. */
> + (void)cpu_topo();
> +#endif
> }
>
> void
>
> Modified: head/sys/powerpc/ps3/platform_ps3.c
> ==============================================================================
> --- head/sys/powerpc/ps3/platform_ps3.c Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/sys/powerpc/ps3/platform_ps3.c Fri Jan 4 18:31:17 2019 (r342771)
> @@ -246,6 +246,8 @@ ps3_smp_start_cpu(platform_t plat, struct pcpu *pc)
> static struct cpu_group *
> ps3_smp_topo(platform_t plat)
> {
> + mp_ncores = 1;
> + smp_threads_per_core = 2;
> return (smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_SMT));
> }
> #endif
>
> Modified: head/sys/powerpc/pseries/platform_chrp.c
> ==============================================================================
> --- head/sys/powerpc/pseries/platform_chrp.c Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/sys/powerpc/pseries/platform_chrp.c Fri Jan 4 18:31:17 2019 (r342771)
> @@ -517,6 +517,8 @@ chrp_smp_topo(platform_t plat)
> ncpus++;
> }
>
> + mp_ncores = ncores;
> +
> if (ncpus % ncores != 0) {
> printf("WARNING: Irregular SMP topology. Performance may be "
> "suboptimal (%d CPUS, %d cores)\n", ncpus, ncores);
> @@ -527,6 +529,7 @@ chrp_smp_topo(platform_t plat)
> if (ncpus == ncores)
> return (smp_topo_none());
>
> + smp_threads_per_core = ncpus / ncores;
> return (smp_topo_1level(CG_SHARE_L1, ncpus / ncores, CG_FLAG_SMT));
> }
> #endif
>
> Modified: head/sys/sys/smp.h
> ==============================================================================
> --- head/sys/sys/smp.h Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/sys/sys/smp.h Fri Jan 4 18:31:17 2019 (r342771)
> @@ -167,8 +167,10 @@ extern cpuset_t logical_cpus_mask;
>
> extern u_int mp_maxid;
> extern int mp_maxcpus;
> +extern int mp_ncores;
> extern int mp_ncpus;
> extern volatile int smp_started;
> +extern int smp_threads_per_core;
>
> extern cpuset_t all_cpus;
> extern cpuset_t cpuset_domain[MAXMEMDOM]; /* CPUs in each NUMA domain. */
>
> Modified: head/sys/x86/x86/mp_x86.c
> ==============================================================================
> --- head/sys/x86/x86/mp_x86.c Fri Jan 4 18:21:49 2019 (r342770)
> +++ head/sys/x86/x86/mp_x86.c Fri Jan 4 18:31:17 2019 (r342771)
> @@ -607,6 +607,7 @@ assign_cpu_ids(void)
> {
> struct topo_node *node;
> u_int smt_mask;
> + int nhyper;
>
> smt_mask = (1u << core_id_shift) - 1;
>
> @@ -615,6 +616,7 @@ assign_cpu_ids(void)
> * beyond MAXCPU. CPU 0 is always assigned to the BSP.
> */
> mp_ncpus = 0;
> + nhyper = 0;
> TOPO_FOREACH(node, &topo_root) {
> if (node->type != TOPO_TYPE_PU)
> continue;
> @@ -642,6 +644,9 @@ assign_cpu_ids(void)
> continue;
> }
>
> + if (cpu_info[node->hwid].cpu_hyperthread)
> + nhyper++;
> +
> cpu_apic_ids[mp_ncpus] = node->hwid;
> apic_cpuids[node->hwid] = mp_ncpus;
> topo_set_pu_id(node, mp_ncpus);
> @@ -651,6 +656,9 @@ assign_cpu_ids(void)
> KASSERT(mp_maxid >= mp_ncpus - 1,
> ("%s: counters out of sync: max %d, count %d", __func__, mp_maxid,
> mp_ncpus));
> +
> + mp_ncores = mp_ncpus - nhyper;
> + smp_threads_per_core = mp_ncpus / mp_ncores;
> }
>
> /*
>
>
--
Rod Grimes rgrimes at freebsd.org
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