[PVE-User] High load on cpu0 with 3.10 pve kernel on proxmox 3.4

Thomas Lamprecht t.lamprecht at proxmox.com
Tue Sep 1 16:15:02 CEST 2015

On 09/01/2015 03:19 PM, Falko Trojahn wrote:
> Am 01.09.2015 um 14:45 schrieb Thomas Lamprecht:
>> There is an huge amount of interrupts from the network card and also
>> from your raid.
>> I'd guess that the main problem it's your network card, make sure the
>> driver of eth0 and eth3 are configured and installed correctly.
> Ok, I'll check'em again.
> What do you think about compiling a newer kernel, since there seems
> to be a patch for specially this problem?
Hmm, but then it's quite strange that it happens on only one node as 
they all have the same kernel and hardware, I guess?

You will need the <version>-pve kernel for Proxmox VE, and the options 
are 2.6.32.x (OpenVZ kernel) and the 3.10.x (RHEL 6 kernel).

PVE4 beta has the 4.1.x kernel at the moment, maybe this could solve the 
problem if it's kernel related.

> ---------------->8-------------------------------8<----------------------
> Since commit 77873803363c "net_dma: mark broken" we no longer pin dma
> engines active for the network-receive-offload use case. As a result
> the ->free_chan_resources() that occurs after the driver self test no
> longer has a NET_DMA induced ->alloc_chan_resources() to back it up. A
> late firing irq can lead to ksoftirqd spinning indefinitely due to the
> tasklet_disable() performed by ->free_chan_resources(). Only
> ->alloc_chan_resources() can clear this condition in affected kernels.
> This problem has been present since commit 3e037454bcfa "I/OAT: Add
> support for MSI and MSI-X" in 2.6.24, but is now exposed. Given the
> NET_DMA use case is deprecated we can revisit moving the driver to use
> threaded irqs. ...
> ---------------->8-------------------------------8<----------------------
> from:
> https://www.kernel.org/pub/linux/kernel/v3.0/ChangeLog-3.10.33
> Cheers,
> Falko

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