Re: Fw: Regression with hyper threading scheduling
From: Peter Williams
Date: Sun Aug 20 2006 - 04:01:47 EST
Andrew Morton wrote:
fyi.. (if replying, please be sure to do it on-list)
Begin forwarded message:
Date: Thu, 17 Aug 2006 13:40:42 +0200
From: Wolfgang Erig <Wolfgang.Erig@xxxxxx>
To: linux-kernel@xxxxxxxxxxxxxxx
Cc: andreas.friedrich@xxxxxxxxxxxxxxxxxxx
Subject: Regression with hyper threading scheduling
Hello kernel hacker,
I have a regression with Hyper-Threading in my box.
If I try e.g. 'while true; do ((ii+=1)); done' on two xterms
- with 2.6.8 both CPUs are running (looking at gkrellm or /proc/stat)
- with 2.6.15/2.6.17 etc. only one CPU is running, sometimes CPU0, sometimes CPU1
Any idea? If you need more info, let me know,
Wolfgang
Kernel 2.6.8.1: Hyper-Threading works:
======================================
uname -a
Linux oak 2.6.8.1 #1 SMP Wed May 10 13:24:21 CEST 2006 i686 GNU/Linux
cat /proc/stat
cpu 22709 4502 2543 1008491 2881 92 1475
cpu0 12800 2428 1426 501276 1859 92 1472
cpu1 9909 2074 1117 507215 1021 0 2
intr 5909520 5214423 7297 0 2 2 0 2 1 0 0 0 0 92935 0 7422 13 0 224861 42603 0 0 0 319959 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ctxt 6553093
btime 1155801409
processes 2525
procs_running 3
procs_blocked 0
Kernel 2.6.17.8 etc.: Hyper-Threading does not work:
====================================================
uname -a
Linux oak 2.6.17.8 #2 SMP PREEMPT Thu Aug 17 11:40:04 CEST 2006 i686 GNU/Linux
cat /proc/stat
cpu 5049 0 744 137292 3113 18 3 0
cpu0 36 0 53 72732 282 18 1 0
cpu1 5012 0 690 64560 2831 0 2 0
intr 221093 182798 880 0 3 4 0 3 1 0 0 0 0 28863 0 6718 12 1811 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ctxt 458461
btime 1155807757
processes 3203
procs_running 1
procs_blocked 0
Some HW-Infos:
==============
lshw
description: Mini Tower Computer
product: SCENIC P / SCENICO P
vendor: FUJITSU SIEMENS
version: SCEP
serial: YBEM738326
width: 32 bits
capabilities: smbios-2.31 dmi-2.31
configuration: boot=normal chassis=mini-tower uuid=FA48F283-A977-D811-A847-912FD384AB1D
*-core
description: Motherboard
product: D1561
vendor: FUJITSU SIEMENS
physical id: 0
version: S26361-D1561
slot: Serial-1
*-firmware
description: BIOS
vendor: FUJITSU SIEMENS // Phoenix Technologies Ltd.
physical id: 0
version: 5.00 R2.14.1561.01 (11/25/2004)
size: 109KB
capacity: 448KB
capabilities: pci pnp apm upgrade shadowing escd cdboot bootselect int13floppynec int13floppytoshiba int13floppy360 int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb agp ls120boot zipboot biosbootspecification
*-cpu
description: CPU
product: Intel(R) Pentium(R) 4 CPU 2.60GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: 15.2.9
slot: CPU
size: 2600MHz
capacity: 2600MHz
width: 32 bits
clock: 800MHz
capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid
configuration: id=1
*-cache:0
description: L1 cache
physical id: 5
slot: L1 Cache
size: 8KB
capacity: 32KB
capabilities: burst synchronous internal write-through data
*-cache:1
description: L2 cache
physical id: 6
slot: L2 Cache
size: 512KB
capacity: 1MB
capabilities: burst internal write-back unified
*-cache:2 DISABLED
description: L3 cache
physical id: 7
slot: L3 Cache
capacity: 16MB
capabilities: internal write-back unified
*-logicalcpu:0
description: Logical CPU
physical id: 1.1
width: 32 bits
capabilities: logical
*-logicalcpu:1
description: Logical CPU
physical id: 1.2
width: 32 bits
...
I'm unable to reproduce this problem with 2.6.18-rc4 on my HT system.
I'm using top with the "last processor" field enabled to observe (rather
than the methods described) and the two bash shells are both getting
100% and are each firmly affixed to different CPUs.
Peter
--
Peter Williams pwil3058@xxxxxxxxxxxxxx
"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/