Re: sched /HT processor
From: Arun Srinivas
Date: Sun Apr 03 2005 - 02:54:37 EST
I looked at my "include/asm-i386/param.h" and the HZ value is 1000.So, I
suppose the timer interrupt frequency is 1000 times per sec. or once every 1
millisec.
So, is scheduler_tick() ( for resceduling) called only once every 1 ms?? I
am measuring the time when 2 of my processes are scheduled in a HT
processor.So, the possible timedifference of when my 2 processes are
scheduled can be only the following:
1) 0 (if both of my processes are scheduled @ the same time since its a HT)
2) 1ms ( this is the min. possible time diff.
3) some value greater than 1 ms
Is the above argument correct?
Thanks
From: Steven Rostedt <rostedt@xxxxxxxxxxx>
To: Arun Srinivas <getarunsri@xxxxxxxxxxx>
CC: LKML <linux-kernel@xxxxxxxxxxxxxxx>
Subject: Re: sched /HT processor
Date: Sat, 02 Apr 2005 20:17:54 -0500
On Sun, 2005-04-03 at 06:07 +0530, Arun Srinivas wrote:
> HI
>
> I have pentium4 hyperthreaded processor.I am using kernel 2.6.5 and i
> rebuilt my kernel with CONFIG_SMP enabled (in this kernel source there
is
> nothing such as CONFIG_SMT...i noticed this only in recent 2.6.11).
>
I don't have a 2.6.5 available, but I do have a 2.6.9 to look at.
> 1) So, after I rebulit it with CONFIG_SMP enabled does linux recogonize
my
> machine as hyperthreaded or as 2 seperate processor? Also, if it does
not
> recogonize it as hyperthreaded(but only as 2 seperate CPU's), does the
> scheduler schedule instruction in the 2 cpu's independently? (does it
> maintain 2 seperate runqueues?
>
I believe even HT on 2.6.11 maintains two different runqueues. But it
doesn't care so much to jump from one runqueue to the next if it is HT.
> 2) If it has indeed recogonized this as hyperthreaded processor...does
the
> scheduler use a common runqueue for the 2 logical processor?
>
No, you wouldn't want to.
> (please read below)
What do you want us to see?
>
*********************************************************************************************************
> (I am attaching the ouput of 'dmesg' (command) on my machine)
>
*************************************************************************************************************
> Apr 2 17:43:12 kulick2 kernel: Linux version 2.6.5-1.358custom
> (root@kulick2) (gcc version 3.3
> .3 20040412 (Red Hat Linux 3.3.3-7)) #133 SMP Wed Mar 30 12:16:27 CST
2005
> Apr 2 17:43:12 kulick2 kernel: BIOS-provided physical RAM map:
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 0000000000000000 -
> 00000000000a0000 (usable)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 00000000000f0000 -
> 0000000000100000 (reserved)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 0000000000100000 -
> 000000001f770000 (usable)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 000000001f770000 -
> 000000001f772000 (ACPI NVS)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 000000001f772000 -
> 000000001f793000 (ACPI data)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 000000001f793000 -
> 000000001f800000 (reserved)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 00000000fec00000 -
> 00000000fec10000 (reserved)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 00000000fecf0000 -
> 00000000fecf1000 (reserved)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 00000000fed20000 -
> 00000000fed90000 (reserved)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 00000000fee00000 -
> 00000000fee10000 (reserved)
> Apr 2 17:43:12 kulick2 kernel: BIOS-e820: 00000000ffb00000 -
> 0000000100000000 (reserved)
> Apr 2 17:43:12 kulick2 kernel: 0MB HIGHMEM available.
> Apr 2 17:43:12 kulick2 kernel: 503MB LOWMEM available.
> Apr 2 17:43:12 kulick2 kernel: ACPI: S3 and PAE do not like each other
for
> now, S3 disabled.
> Apr 2 17:43:12 kulick2 kernel: found SMP MP-table at 000fe710
> Apr 2 17:43:12 kulick2 kernel: On node 0 totalpages: 128880
> Apr 2 17:43:12 kulick2 kernel: DMA zone: 4096 pages, LIFO batch:1
> Apr 2 17:43:12 kulick2 kernel: Normal zone: 124784 pages, LIFO
batch:16
> Apr 2 17:43:12 kulick2 kernel: HighMem zone: 0 pages, LIFO batch:1
> Apr 2 17:43:12 kulick2 kernel: DMI 2.3 present.
> Apr 2 17:43:12 kulick2 kernel: Using APIC driver default
> Apr 2 17:43:12 kulick2 kernel: ACPI: RSDP (v000 DELL
> ) @
> 0x000feba0
> Apr 2 17:43:12 kulick2 kernel: ACPI: RSDT (v001 DELL GX270
0x00000007
> ASL 0x00000061) @
> 0x000fd192
> Apr 2 17:43:12 kulick2 kernel: ACPI: FADT (v001 DELL GX270
0x00000007
> ASL 0x00000061) @
> 0x000fd1ca
> Apr 2 17:43:12 kulick2 kernel: ACPI: SSDT (v001 DELL st_ex
0x00001000
> MSFT 0x0100000d) @
> 0xfffd4eee
> Apr 2 17:43:12 kulick2 irqbalance: irqbalance startup succeeded
> Apr 2 17:43:12 kulick2 kernel: ACPI: MADT (v001 DELL GX270
0x00000007
> ASL 0x00000061) @
> 0x000fd23e
> Apr 2 17:43:12 kulick2 kernel: ACPI: BOOT (v001 DELL GX270
0x00000007
> ASL 0x00000061) @
> 0x000fd2aa
> Apr 2 17:43:12 kulick2 kernel: ACPI: ASF! (v016 DELL GX270
0x00000007
> ASL 0x00000061) @
> 0x000fd2d2
> Apr 2 17:43:12 kulick2 kernel: ACPI: DSDT (v001 DELL dt_ex
0x00001000
> MSFT 0x0100000d) @
> 0x00000000
> Apr 2 17:43:12 kulick2 kernel: ACPI: PM-Timer IO Port: 0x808
> Apr 2 17:43:12 kulick2 kernel: ACPI: LAPIC (acpi_id[0x01]
lapic_id[0x00]
> enabled)
> Apr 2 17:43:12 kulick2 kernel: Processor #0 15:2 APIC version 20
> Apr 2 17:43:12 kulick2 kernel: ACPI: LAPIC (acpi_id[0x02]
lapic_id[0x01]
> enabled)
> Apr 2 17:43:12 kulick2 kernel: Processor #1 15:2 APIC version 20
> Apr 2 17:43:12 kulick2 kernel: ACPI: LAPIC (acpi_id[0x03]
lapic_id[0x01]
> disabled)
> Apr 2 17:43:12 kulick2 kernel: ACPI: LAPIC (acpi_id[0x04]
lapic_id[0x03]
> disabled)
> Apr 2 17:43:12 kulick2 kernel: ACPI: IOAPIC (id[0x02]
address[0xfec00000]
> global_irq_base[0x0]
> )
> Apr 2 17:43:12 kulick2 kernel: IOAPIC[0]: Assigned apic_id 2
> Apr 2 17:43:12 kulick2 kernel: IOAPIC[0]: apic_id 2, version 32,
address
> 0xfec00000, GSI 0-23
> Apr 2 17:43:12 kulick2 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 0
> global_irq 2 dfl dfl)
> Apr 2 17:43:12 kulick2 kernel: ACPI: INT_SRC_OVR (bus 0 bus_irq 9
> global_irq 9 high level)
> Apr 2 17:43:12 kulick2 kernel: Enabling APIC mode: Flat. Using 1 I/O
> APICs
> Apr 2 17:43:12 kulick2 kernel: Using ACPI (MADT) for SMP configuration
> information
> Apr 2 17:43:12 kulick2 portmap: portmap startup succeeded
> Apr 2 17:43:12 kulick2 kernel: Built 1 zonelists
> Apr 2 17:43:12 kulick2 kernel: Kernel command line: ro root=LABEL=/
rhgb
> quiet
> Apr 2 17:43:12 kulick2 kernel: mapped 4G/4G trampoline to fffeb000.
> Apr 2 17:43:12 kulick2 kernel: Initializing CPU#0
> Apr 2 17:43:12 kulick2 kernel: CPU 0 irqstacks, hard=023cb000
soft=023ab000
> Apr 2 17:43:12 kulick2 kernel: PID hash table entries: 2048 (order 11:
> 16384 bytes)
> Apr 2 17:43:12 kulick2 kernel: Detected 2993.225 MHz processor.
> Apr 2 17:43:12 kulick2 kernel: Using pmtmr for high-res timesource
> Apr 2 17:43:12 kulick2 kernel: Console: colour VGA+ 80x25
> Apr 2 17:43:12 kulick2 kernel: Memory: 505996k/515520k available (1744k
> kernel code, 8772k res
> erved, 756k data, 180k init, 0k highmem)
> Apr 2 17:43:12 kulick2 kernel: Calibrating delay loop... 5931.00
BogoMIPS
> Apr 2 17:43:12 kulick2 kernel: Security Scaffold v1.0.0 initialized
> Apr 2 17:43:12 kulick2 kernel: SELinux: Initializing.
> Apr 2 17:43:12 kulick2 kernel: SELinux: Starting in permissive mode
> Apr 2 17:43:12 kulick2 kernel: There is already a security framework
> initialized, register_sec
> urity failed.
> Apr 2 17:43:12 kulick2 kernel: Failure registering capabilities with
the
> kernel
> Apr 2 17:43:12 kulick2 kernel: selinux_register_security: Registering
> secondary module capabi
> lity
> Apr 2 17:43:12 kulick2 kernel: Capability LSM initialized
> Apr 2 17:43:12 kulick2 kernel: Dentry cache hash table entries: 32768
> (order: 5, 131072 bytes)
> Apr 2 17:43:12 kulick2 kernel: Inode-cache hash table entries: 32768
> (order: 5, 131072 bytes)
> Apr 2 17:43:12 kulick2 kernel: Mount-cache hash table entries: 512
(order:
> 0, 4096 bytes)
> Apr 2 17:43:12 kulick2 kernel: CPU: Trace cache: 12K uops, L1 D cache:
8K
> Apr 2 17:43:12 kulick2 rpc.statd[2019]: Version 1.0.6 Starting
> Apr 2 17:43:12 kulick2 kernel: CPU: L2 cache: 512K
> Apr 2 17:43:12 kulick2 kernel: CPU: Physical Processor ID: 0
> Apr 2 17:43:12 kulick2 rpc.statd[2019]: gethostbyname error for kulick2
> Apr 2 17:43:12 kulick2 kernel: Intel machine check architecture
supported.
> Apr 2 17:43:12 kulick2 kernel: Intel machine check reporting enabled on
> CPU#0.
> Apr 2 17:43:12 kulick2 nfslock: rpc.statd startup succeeded
> Apr 2 17:43:12 kulick2 kernel: CPU#0: Intel P4/Xeon Extended MCE MSRs
(12)
> available
> Apr 2 17:43:12 kulick2 kernel: CPU#0: Thermal monitoring enabled
> Apr 2 17:43:12 kulick2 kernel: Enabling fast FPU save and restore...
done.
> Apr 2 17:43:12 kulick2 kernel: Enabling unmasked SIMD FPU exception
> support... done.
> Apr 2 17:43:12 kulick2 kernel: Checking 'hlt' instruction... OK.
> Apr 2 17:43:12 kulick2 kernel: POSIX conformance testing by UNIFIX
> Apr 2 17:43:12 kulick2 kernel: CPU0: Intel(R) Pentium(R) 4 CPU 3.00GHz
> stepping 09
> Apr 2 17:43:12 kulick2 kernel: per-CPU timeslice cutoff: 1462.93 usecs.
> Apr 2 17:43:12 kulick2 kernel: task migration cache decay timeout: 2
msecs.
> Apr 2 17:43:12 kulick2 kernel: enabled ExtINT on CPU#0
> Apr 2 17:43:12 kulick2 kernel: ESR value before enabling vector:
00000040
> Apr 2 17:43:12 kulick2 kernel: ESR value after enabling vector:
00000000
> Apr 2 17:43:12 kulick2 kernel: Booting processor 1/1 eip 2000
> Apr 2 17:43:12 kulick2 kernel: CPU 1 irqstacks, hard=023cc000
soft=023ac000
> Apr 2 17:43:12 kulick2 kernel: Initializing CPU#1
> Apr 2 17:43:12 kulick2 kernel: masked ExtINT on CPU#1
> Apr 2 17:43:12 kulick2 kernel: ESR value before enabling vector:
00000000
> Apr 2 17:43:12 kulick2 kernel: ESR value after enabling vector:
00000000
> Apr 2 17:43:12 kulick2 kernel: Calibrating delay loop... 5980.16
BogoMIPS
> Apr 2 17:43:12 kulick2 kernel: CPU: Trace cache: 12K uops, L1 D cache:
8K
> Apr 2 17:43:12 kulick2 kernel: CPU: L2 cache: 512K
> Apr 2 17:43:12 kulick2 kernel: CPU: Physical Processor ID: 0
> Apr 2 17:43:12 kulick2 kernel: Intel machine check architecture
supported.
> Apr 2 17:43:12 kulick2 kernel: Intel machine check reporting enabled on
> CPU#1.
> Apr 2 17:43:12 kulick2 kernel: CPU#1: Intel P4/Xeon Extended MCE MSRs
(12)
> available
> Apr 2 17:43:12 kulick2 kernel: CPU#1: Thermal monitoring enabled
> Apr 2 17:43:12 kulick2 kernel: CPU1: Intel(R) Pentium(R) 4 CPU 3.00GHz
> stepping 09
> Apr 2 17:43:12 kulick2 kernel: Total of 2 processors activated
(11911.16
> BogoMIPS).
> Apr 2 17:43:12 kulick2 kernel: cpu_sibling_map[0] = 1
> Apr 2 17:43:12 kulick2 kernel: cpu_sibling_map[1] = 0
Here you see that you have two CPUs. 0 is the sibling of 1 and 1 to 0.
This just shows that you have HT. If you were to have a dual xeon, then
you would see 4 CPUs and two pairs.
-- Steve
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