Dual 2.40ghz xeon w/hyperthreading

[jeev]

Which would give me the best performance? To disable hyperthreading or
enable machdep.cpu_idle_hlt, and if I were to enable it, it would be from
loader.conf or?

j

-----Original Message-----
From: owner-freebsd-smp at freebsd.org [mailto:owner-freebsd-smp at freebsd.org]
On Behalf Of Petri Helenius
Sent: Friday, April 25, 2003 4:28 AM
To: jeev
Cc: freebsd-smp at freebsd.org
Subject: Re: Dual 2.40ghz xeon w/hyperthreading

jeev wrote:

>Basically guys, this box is not exceeding an ide computer I have on idea.
>
>I noticed the dual xeon to be slow. So I ran:
>
>dd if=/dev/urandom of=/dev/null bs=1m count=1024
>
>on 2 servers, 1 is the top one and 1 is the xeon.
>Obviously the ide killed the scsi with dual cpu's running hyperthreading,
>why?
>  
>
Hypethreading gives you two virtual CPU's out of one real one. They perform
at ~60-70% of the capacity of real one.

Enable machdep.cpu_idle_hlt  (disabled by default on SMP) to have the 
other virtual
core to execute HLT when it's not doing anything useful except busylooping,
which is what happens now.

Or even better, disable hypethreading to recover real performance.

Pete

>
>-SINGLE 2.4ghz p4 w/1gb ram and 80gig ide
>
>1073741824 bytes transferred in 266.387823 secs (4030747 bytes/sec)
>2.4ghz
>CPU: Intel(R) Pentium(R) 4 CPU 2.40GHz (2399.74-MHz 686-class CPU)
>  Origin = "GenuineIntel"  Id = 0xf27  Stepping = 7
> 
>Features=0xbfebf9ff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,MTRR,PGE,MCA,CMO
V
>,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
>real memory  = 1073676288 (1048512K bytes)
>avail memory = 1039519744 (1015156K bytes)
>ad0: 76319MB <WDC WD800JB-00DUA1> [155061/16/63] at ata0-master UDMA100
>-----------------------
>
>
>
>-dual 2.4ghz xeon each with hyperthreading, 2gb ram ddr, 73gb scsi hd.
>
>1073741824 bytes transferred in 410.476271 secs (2615844 bytes/sec)
>CPU: Intel(R) Xeon(TM) CPU 2.40GHz (2395.92-MHz 686-class CPU)
>  Origin = "GenuineIntel"  Id = 0xf27  Stepping = 7
>Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MC
A
>,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
>  Hyperthreading: 2 logical CPUs
>real memory  = 2146959360 (2096640K bytes)
>avail memory = 2085502976 (2036624K bytes)
>Programming 24 pins in IOAPIC #0
>IOAPIC #0 intpin 2 -> irq 0
>Programming 24 pins in IOAPIC #1
>Programming 24 pins in IOAPIC #2
>Programming 24 pins in IOAPIC #3
>Programming 24 pins in IOAPIC #4
>FreeBSD/SMP: Multiprocessor motherboard
> cpu0 (BSP): apic id:  0, version: 0x00050014, at 0xfee00000
> cpu1 (AP):  apic id:  6, version: 0x00050014, at 0xfee00000
> cpu2 (AP):  apic id:  1, version: 0x00050014, at 0xfee00000
> cpu3 (AP):  apic id:  7, version: 0x00050014, at 0xfee00000
> io0 (APIC): apic id:  2, version: 0x00178020, at 0xfec00000
> io1 (APIC): apic id:  3, version: 0x00178020, at 0xfec80000
> io2 (APIC): apic id:  4, version: 0x00178020, at 0xfec80400
> io3 (APIC): apic id:  5, version: 0x00178020, at 0xfec81000
> io4 (APIC): apic id:  8, version: 0x00178020, at 0xfec81400
>da0 at ahc0 bus 0 target 0 lun 0
>da0: <SEAGATE ST373307LC 0004> Fixed Direct Access SCSI-3 device 
>da0: 160.000MB/s transfers (80.000MHz, offset 63, 16bit), Tagged Queueing
>Enabled
>da0: 70007MB (143374744 512 byte sectors: 255H 63S/T 8924C)
>
>what could be causing this issue?
>
>Thanks!
>
>j
>
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>  
>



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