# Wrong memory bus frequencies

## VanFanel

Hello there

I'm trying to find out the case of some hippus in my system, and I noticed that lspci is reporting 66Mhz for the RAM memory speed. That's not right, I believe, as my computer is a 2009 one with Intel Core2Duo and based around the Nvidia MPC79 chipset.

Here's a partial lspi output:

```
$lspci -v

00:00.0 Host bridge: nVidia Corporation Device 0a82 (rev b1)

   Flags: bus master, 66MHz, fast devsel, latency 0

00:00.1 RAM memory: nVidia Corporation Device 0a88 (rev b1)

   Flags: bus master, 66MHz, fast devsel, latency 0

00:03.0 ISA bridge: nVidia Corporation Device 0aae (rev b2)

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0

   I/O ports at 2000 [size=256]

00:03.1 RAM memory: nVidia Corporation Device 0aa4 (rev b1)

   Flags: 66MHz, fast devsel

00:03.2 SMBus: nVidia Corporation Device 0aa2 (rev b1)

   Subsystem: nVidia Corporation Device cb79

   Flags: 66MHz, fast devsel, IRQ 15

   I/O ports at 2180 [size=64]

   I/O ports at 2140 [size=64]

   I/O ports at 2100 [size=64]

   Capabilities: [44] Power Management version 2

   Kernel driver in use: nForce2_smbus

00:03.3 RAM memory: nVidia Corporation Device 0a89 (rev b1)

   Flags: 66MHz, fast devsel

00:03.4 RAM memory: nVidia Corporation Device 0a98 (rev b1)

   Subsystem: nVidia Corporation Device cb79

   Flags: 66MHz, fast devsel

00:03.5 Co-processor: nVidia Corporation Device 0aa3 (rev b1)

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 14

   Memory at 53400000 (32-bit, non-prefetchable) [size=512K]

00:04.0 USB Controller: nVidia Corporation Device 0aa5 (rev b1) (prog-if 10 [OHCI])

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 17

   Memory at 53488000 (32-bit, non-prefetchable) [size=4K]

   Capabilities: [44] Power Management version 2

   Kernel driver in use: ohci_hcd

00:04.1 USB Controller: nVidia Corporation Device 0aa6 (rev b1) (prog-if 20 [EHCI])

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 19

   Memory at 53489200 (32-bit, non-prefetchable) [size=256]

   Capabilities: [44] Debug port: BAR=1 offset=00a0

   Capabilities: [80] Power Management version 2

   Kernel driver in use: ehci_hcd

00:06.0 USB Controller: nVidia Corporation Device 0aa7 (rev b1) (prog-if 10 [OHCI])

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 16

   Memory at 53487000 (32-bit, non-prefetchable) [size=4K]

   Capabilities: [44] Power Management version 2

   Kernel driver in use: ohci_hcd

00:06.1 USB Controller: nVidia Corporation Device 0aa9 (rev b1) (prog-if 20 [EHCI])

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 18

   Memory at 53489100 (32-bit, non-prefetchable) [size=256]

   Capabilities: [44] Debug port: BAR=1 offset=00a0

   Capabilities: [80] Power Management version 2

   Kernel driver in use: ehci_hcd

00:08.0 Audio device: nVidia Corporation Device 0ac0 (rev b1)

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 23

   Memory at 53480000 (32-bit, non-prefetchable) [size=16K]

   Capabilities: [44] Power Management version 2

   Kernel driver in use: HDA Intel

   Kernel modules: snd-hda-intel

00:09.0 PCI bridge: nVidia Corporation Device 0aab (rev b1) (prog-if 01 [Subtractive decode])

   Flags: bus master, 66MHz, fast devsel, latency 0

   Bus: primary=00, secondary=01, subordinate=01, sec-latency=0

   Memory behind bridge: 53300000-533fffff

   Capabilities: [b8] Subsystem: nVidia Corporation Device cb79

00:0a.0 Ethernet controller: nVidia Corporation MCP79 Ethernet (rev b1)

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 20

   Memory at 53486000 (32-bit, non-prefetchable) [size=4K]

   I/O ports at 21e0 [size=8]

   Memory at 53489000 (32-bit, non-prefetchable) [size=256]

   Memory at 53489300 (32-bit, non-prefetchable) [size=16]

   Capabilities: [44] Power Management version 2

   Capabilities: [50] Message Signalled Interrupts: Mask+ 64bit+ Count=1/16 Enable-

   Kernel driver in use: forcedeth

00:0b.0 IDE interface: nVidia Corporation Device 0ab5 (rev b1) (prog-if 85 [Master SecO PriO])

   Subsystem: nVidia Corporation Device cb79

   Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 21

   I/O ports at 21d8 [size=8]

   I/O ports at 21ec [size=4]

   I/O ports at 21d0 [size=8]

   I/O ports at 21e8 [size=4]

   I/O ports at 21c0 [size=16]

   Memory at 53484000 (32-bit, non-prefetchable) [size=8K]

   Capabilities: [44] Power Management version 2

   Capabilities: [8c] SATA HBA <?>

   Capabilities: [b0] Message Signalled Interrupts: Mask- 64bit+ Count=1/8 Enable-

   Kernel driver in use: ahci

```

I believe those low frequencies are causing a big bottleneck in my system, but I don't know how to correct it as all my hardware is already working "right" with my kernel (2.6.32)

Any ideas? 

regards

----------

## Rexilion

For me it also reports 66 MHZ, I don't think that that has anything to do on the MHZ what is displayed on the package the RAM sticks came in. What kind of hiccups are you experiencing? Are the hiccups happening during a particular program/moment?

----------

## VanFanel

I'm having hiccups with multimedia programs and emulators that need to load several .so libraries.

Those hiccups occurr in the first run of the programs but not on subsequent runs. 

I've another thread opened for that (I'm currently investigating into prefetching those libraries as link31 has suggested), but I also need to be sure my hardware is working well. 

How can current systems be running at 66Mhz memory bus speed? Is that right/normal or am I missing something in my kernel?

----------

## Rexilion

The hiccups are not part of a hardware problem. You can set the readahead like this (assuming your disk is /dev/sda):

```
blockdev --setra 16384 /dev/sda
```

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## aderesch

 *VanFanel wrote:*   

> How can current systems be running at 66Mhz memory bus speed?

 

They aren't and haven't done so for quite a while. Output of lspci gives information about PCI devices and has nothing to do with memory or cpu frequencies.

ad

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## VanFanel

So.. is 66Mhz a good frequency for pci devices running on the MPC79 chipset?

There's nothing wrong with those results? I believe 66Mhz is also slow for a PCI bus video device nowadays, for example...

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## Ant P.

If you look carefully you'll see that "66MHz" is listed as a bit flag, i.e. not a number. All it means is that your PCI bus isn't running at 33MHz.

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## VanFanel

So what's the speed my PCI bus is running at? 

This is crazy, but very fun  :Very Happy: 

----------

