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SMP on x86: Difference between revisions
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* [http://osdir.com/ml/linux.ports.x86-64.general/2005-10/msg00022.html This LKML thread] provides much information | * [http://osdir.com/ml/linux.ports.x86-64.general/2005-10/msg00022.html This LKML thread] provides much information | ||
* The [[cpuid]] instruction can interrogate each processing unit | * The [[cpuid]] instruction can interrogate each processing unit | ||
* [[Cpuset|CPUsets]] | |||
[[Category: x86]] | [[Category: x86]] | ||
Revision as of 11:24, 27 October 2009
The primary specification for multiprocessor x86-based setups is the Intel MultiProcessor Specification (last updated, AFAIK, to revision-006 on 1995-05-15).
Interrupts
- IO-APIC routes hardware interrupts to various CPUs (Linux's IO-APIC.txt)
[recombinator](0) $ cat /proc/interrupts
CPU0 CPU1
0: 491 0 IO-APIC-edge timer
8: 87 0 IO-APIC-edge rtc0
9: 0 0 IO-APIC-fasteoi acpi
16: 609652 0 IO-APIC-fasteoi uhci_hcd:usb1, heci
17: 0 0 IO-APIC-fasteoi pata_marvell
18: 33141 0 IO-APIC-fasteoi sata_promise, uhci_hcd:usb5, ehci_hcd:usb6
19: 0 0 IO-APIC-fasteoi uhci_hcd:usb4
21: 15985105 0 IO-APIC-fasteoi uhci_hcd:usb2, ath
23: 8730160 0 IO-APIC-fasteoi uhci_hcd:usb3, ehci_hcd:usb7
29: 1855556 0 PCI-MSI-edge i915
30: 1109316 0 PCI-MSI-edge ahci
31: 66952 0 PCI-MSI-edge e1000
NMI: 0 0 Non-maskable interrupts
LOC: 14417376 16273096 Local timer interrupts
SPU: 0 0 Spurious interrupts
RES: 150950 182106 Rescheduling interrupts
CAL: 278 611 Function call interrupts
TLB: 33349 53705 TLB shootdowns
TRM: 0 0 Thermal event interrupts
THR: 0 0 Threshold APIC interrupts
ERR: 0
MIS: 0
[recombinator](0) $
ACPI
- The MADT table can supply multiprocessor configuration
- MP Table. The FreeBSD program mptable(1) can dump this:
[bryhlath](0) $ sudo mptable =============================================================================== MPTable ------------------------------------------------------------------------------- MP Floating Pointer Structure: location: BIOS physical address: 0x000fbd10 signature: '_MP_' length: 16 bytes version: 1.4 checksum: 0xc6 mode: Virtual Wire ------------------------------------------------------------------------------- MP Config Table Header: physical address: 0x000fbb10 signature: 'PCMP' base table length: 508 version: 1.4 checksum: 0x84 OEM ID: 'QEMUCPU ' Product ID: '0.1 ' OEM table pointer: 0x00000000 OEM table size: 0 entry count: 34 local APIC address: 0xfee00000 extended table length: 0 extended table checksum: 0 ------------------------------------------------------------------------------- MP Config Base Table Entries: -- Processors: APIC ID Version State Family Model Step Flags 0 0x11 BSP, usable 6 0 0 0x0201 1 0x11 AP, unusable 6 0 0 0x0201 2 0x11 AP, unusable 6 0 0 0x0201 3 0x11 AP, unusable 6 0 0 0x0201 4 0x11 AP, unusable 6 0 0 0x0201 5 0x11 AP, unusable 6 0 0 0x0201 6 0x11 AP, unusable 6 0 0 0x0201 7 0x11 AP, unusable 6 0 0 0x0201 8 0x11 AP, unusable 6 0 0 0x0201 9 0x11 AP, unusable 6 0 0 0x0201 10 0x11 AP, unusable 6 0 0 0x0201 11 0x11 AP, unusable 6 0 0 0x0201 12 0x11 AP, unusable 6 0 0 0x0201 13 0x11 AP, unusable 6 0 0 0x0201 14 0x11 AP, unusable 6 0 0 0x0201 15 0x11 AP, unusable 6 0 0 0x0201 -- Bus: Bus ID Type 0 ISA -- I/O APICs: APIC ID Version State Address 1 0x11 usable 0xfec00000 -- I/O Ints: Type Polarity Trigger Bus ID IRQ APIC ID PIN# INT conforms conforms 0 0 1 0 INT conforms conforms 0 1 1 1 INT conforms conforms 0 2 1 2 INT conforms conforms 0 3 1 3 INT conforms conforms 0 4 1 4 INT conforms conforms 0 5 1 5 INT conforms conforms 0 6 1 6 INT conforms conforms 0 7 1 7 INT conforms conforms 0 8 1 8 INT conforms conforms 0 9 1 9 INT conforms conforms 0 10 1 10 INT conforms conforms 0 11 1 11 INT conforms conforms 0 12 1 12 INT conforms conforms 0 13 1 13 INT conforms conforms 0 14 1 14 INT conforms conforms 0 15 1 15 =============================================================================== [bryhlath](0) $
- Interactions with cpuid
- HyperThreading (Intel SMT) requires CPU, BIOS and OS support. Introduced on the P4.
- Found on (all) i7's, some Atoms, and some P4's and Core2Duo's (especially those with Xeon branding).
- Pentium-M and Celerons usually lack SMT.
/proc/cpuinfo
On Linux kernels with the proc filesystem enabled (and FreeBSD kernels with the linprocfs module loaded, although this does not provide all of the information as native Linux /proc/cpuinfo), the mounted proc/linprocfs filesystem contains a file cpuinfo (this is independent of any CPU-related modules being loaded, particularly cpuid on Linux or either OS's cpu module). Interpreting this file, as it pertains to multiple execution units, can be difficult. The following applies to Linux 2.6 kernels:
- A physical_id corresponds to a socket ("physical package"), of which there are >=1 per machine. Physical IDs do not necessarily monotonically increase across processors, and thus the maximum physical_id does not by itself determine the number of sockets!
- A core_id corresponds to a core ("logical processor"), of which there are >=1 per physical_id
- A processor ID corresponds to an architectural state (HyperThreading == 2 per HyperThreaded core)
- HyperThreading is in use only if 'siblings' != 'cpu cores' (from http://kbase.redhat.com/faq/FAQ_46_10715.shtm)
- The 'ht' processor capabilities bit corresponds not to HyperThreading, but to the ability to report sibling count
Examples
I've removed all output from the following examples, save that related to SMP identification.
- EMT64 Xeon, no HyperThreading support, 4 cores per socket, 4 sockets: 16 total execution units (2.6.26) (Dell R900)
[wopr](0) $ cat /proc/cpuinfo | egrep ^proc\|^model\ \|^phys\|^sib\|^core\|^cpu\ c\|^ap\|^init processor : 0 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 0 siblings : 4 core id : 0 cpu cores : 4 apicid : 0 initial apicid : 0 processor : 1 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 2 siblings : 4 core id : 0 cpu cores : 4 apicid : 8 initial apicid : 8 processor : 2 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 4 siblings : 4 core id : 0 cpu cores : 4 apicid : 16 initial apicid : 16 processor : 3 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 6 siblings : 4 core id : 0 cpu cores : 4 apicid : 24 initial apicid : 24 processor : 4 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 0 siblings : 4 core id : 2 cpu cores : 4 apicid : 2 initial apicid : 2 processor : 5 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 2 siblings : 4 core id : 2 cpu cores : 4 apicid : 10 initial apicid : 10 processor : 6 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 4 siblings : 4 core id : 2 cpu cores : 4 apicid : 18 initial apicid : 18 processor : 7 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 6 siblings : 4 core id : 2 cpu cores : 4 apicid : 26 initial apicid : 26 processor : 8 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 0 siblings : 4 core id : 1 cpu cores : 4 apicid : 1 initial apicid : 1 processor : 9 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 2 siblings : 4 core id : 1 cpu cores : 4 apicid : 9 initial apicid : 9 processor : 10 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 4 siblings : 4 core id : 1 cpu cores : 4 apicid : 17 initial apicid : 17 processor : 11 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 6 siblings : 4 core id : 1 cpu cores : 4 apicid : 25 initial apicid : 25 processor : 12 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 0 siblings : 4 core id : 3 cpu cores : 4 apicid : 3 initial apicid : 3 processor : 13 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 2 siblings : 4 core id : 3 cpu cores : 4 apicid : 11 initial apicid : 11 processor : 14 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 4 siblings : 4 core id : 3 cpu cores : 4 apicid : 19 initial apicid : 19 processor : 15 model name : Intel(R) Xeon(R) CPU X7350 @ 2.93GHz physical id : 6 siblings : 4 core id : 3 cpu cores : 4 apicid : 27 initial apicid : 27 [wopr](0) $
- Xeon E5520, HyperThreading enabled, 4 cores per socket, 2 sockets: 16 total execution units (Dell R710)
[dumbledore](0) $ egrep '^(proc|phys|sib|acpi|model )|core' /proc/cpuinfo processor : 0 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 0 cpu cores : 4 processor : 1 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 0 cpu cores : 4 processor : 2 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 1 cpu cores : 4 processor : 3 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 1 cpu cores : 4 processor : 4 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 2 cpu cores : 4 processor : 5 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 2 cpu cores : 4 processor : 6 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 3 cpu cores : 4 processor : 7 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 3 cpu cores : 4 processor : 8 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 0 cpu cores : 4 processor : 9 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 0 cpu cores : 4 processor : 10 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 1 cpu cores : 4 processor : 11 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 1 cpu cores : 4 processor : 12 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 2 cpu cores : 4 processor : 13 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 2 cpu cores : 4 processor : 14 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 1 siblings : 8 core id : 3 cpu cores : 4 processor : 15 model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz physical id : 0 siblings : 8 core id : 3 cpu cores : 4 [dumbledore](0) $
- Core 2 Duo, no HyperThreading support, 2 cores per socket, 1 socket: 2 total execution units (2.6.26)
[recombinator](0) $ cat /proc/cpuinfo processor : 0 model name : Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz physical id : 0 siblings : 2 core id : 0 cpu cores : 2 apicid : 0 initial apicid : 0 processor : 1 model name : Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz physical id : 0 siblings : 2 core id : 1 cpu cores : 2 apicid : 1 initial apicid : 1 [recombinator](0) $
- P4 Xeon, HyperThreading enabled, 1 core per socket, 2 sockets: 4 total execution units (2.6.25-2-686)
scurdev@hrududu:~$ cat /proc/cpuinfo processor : 0 model name : Intel(R) Xeon(TM) CPU 2.40GHz physical id : 0 siblings : 2 core id : 0 cpu cores : 1 processor : 1 model name : Intel(R) Xeon(TM) CPU 2.40GHz physical id : 0 siblings : 2 core id : 0 cpu cores : 1 processor : 2 model name : Intel(R) Xeon(TM) CPU 2.40GHz physical id : 3 siblings : 2 core id : 0 cpu cores : 1 processor : 3 model name : Intel(R) Xeon(TM) CPU 2.40GHz physical id : 3 siblings : 2 core id : 0 cpu cores : 1 scurdev@hrududu:~$
- P4 Xeon, HyperThreading disabled, 1 core per socket, 2 sockets: 2 total execution units (2.6.25-2-686)
[aho](0) $ cat /proc/cpuinfo processor : 0 model name : Intel(R) Xeon(TM) CPU 2.80GHz processor : 1 model name : Intel(R) Xeon(TM) CPU 2.80GHz [aho](0) $
- P4 Xeon Celeron, HyperThreading disabled, 1 core per socket, 1 socket: 1 total execution unit (2.6.25-2-686)
[knuth](0) $ cat /proc/cpuinfo processor : 0 model name : Intel(R) Celeron(R) CPU 2.00GHz [knuth](0) $
Sysctl
On FreeBSD, CPU/SMP information is primarily exported through the sysctl(8) interface. Seemingly relevant sysctls are listed below:
- kern.smp.cpus and hw.ncpu
- machdep.hyperthreading.allowed
- kern.threads.virtual_cpu
libvirt
- virsh(1)'s nodeinfo command can be pretty useful:
[wopr](0) $ virsh nodeinfo CPU model: x86_64 CPU(s): 16 CPU frequency: 1600 MHz CPU socket(s): 4 Core(s) per socket: 4 Thread(s) per core: 1 NUMA cell(s): 1 Memory size: 66113480 kB [wopr](0) $
[recombinator](0) $ sudo virsh nodeinfo CPU model: x86_64 CPU(s): 2 CPU frequency: 1596 MHz CPU socket(s): 1 Core(s) per socket: 2 Thread(s) per core: 1 NUMA cell(s): 1 Memory size: 3908568 kB [recombinator](0) $
See also
- This LKML thread provides much information
- The cpuid instruction can interrogate each processing unit
- CPUsets
