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#1 2012-09-29 10:41:33

Agamemnon
Member
From: France
Registered: 2011-05-05
Posts: 42

Irqbalance with Core2Duo CPU?

Hi all!

I recently heard about Irqbalance but I wonder if it makes sense to use this with a Core2Duo CPU to save power (it's a laptop) and maybe gain some perf?

What do you think about it?


Pc: Intel core i7, 8Gb RAM, Archlinux 64bits, Gnome 3
Laptop 1: Intel Core2Duo, 4Gb RAM, Archlinux 64bits, Gnome 3
Laptop 2: Intel P4 HT, 512Mb RAM, Archlinux 32 bits, Gnome 3 too

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#2 2012-09-29 15:06:17

brebs
Member
Registered: 2007-04-03
Posts: 3,439

Re: Irqbalance with Core2Duo CPU?

Take a look:

cat /proc/interrupts

If your interrupts are already balanced across cores (which they most probably are), then irqbalance won't help.

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#3 2012-09-29 21:13:07

Agamemnon
Member
From: France
Registered: 2011-05-05
Posts: 42

Re: Irqbalance with Core2Duo CPU?

Indeed, cat /proc/interrupts shows:

            CPU0       CPU1       
   0:       8291       8460   IO-APIC-edge      timer
   1:        117        106   IO-APIC-edge      i8042
   8:          1          0   IO-APIC-edge      rtc0
   9:        159        163   IO-APIC-fasteoi   acpi
  12:       6912       6857   IO-APIC-edge      i8042
  16:          4          1   IO-APIC-fasteoi   uhci_hcd:usb2, mmc0, firewire_ohci
  18:          0          0   IO-APIC-fasteoi   uhci_hcd:usb7
  19:          0          0   IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb4, uhci_hcd:usb6
  21:          0          0   IO-APIC-fasteoi   uhci_hcd:usb3
  23:         43         48   IO-APIC-fasteoi   uhci_hcd:usb5, ehci_hcd:usb8
  44:       7534       7348   PCI-MSI-edge      radeon
  45:       6818       6768   PCI-MSI-edge      ahci
  46:         83         77   PCI-MSI-edge      snd_hda_intel
  47:         75         72   PCI-MSI-edge      snd_hda_intel
  48:          1          0   PCI-MSI-edge      eth0
  49:       4041       3928   PCI-MSI-edge      iwlwifi
 NMI:          1          1   Non-maskable interrupts
 LOC:      11107      12559   Local timer interrupts
 SPU:          0          0   Spurious interrupts
 PMI:          1          1   Performance monitoring interrupts
 IWI:          0          0   IRQ work interrupts
 RTR:          0          0   APIC ICR read retries
 RES:       4721       4737   Rescheduling interrupts
 CAL:         59         37   Function call interrupts
 TLB:       6376       2266   TLB shootdowns
 TRM:          0          0   Thermal event interrupts
 THR:          0          0   Threshold APIC interrupts
 MCE:          0          0   Machine check exceptions
 MCP:          1          1   Machine check polls
 ERR:          0
 MIS:          0

So it seems it's correctly balanced smile


Pc: Intel core i7, 8Gb RAM, Archlinux 64bits, Gnome 3
Laptop 1: Intel Core2Duo, 4Gb RAM, Archlinux 64bits, Gnome 3
Laptop 2: Intel P4 HT, 512Mb RAM, Archlinux 32 bits, Gnome 3 too

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