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

Falko Trojahn trojahn+proxmox at pluspol.info
Fri Sep 11 11:31:14 CEST 2015

Am 01.09.2015 um 16:15 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?
Yes, that's the strange thing.

> 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).
I'll try compile from https://git.proxmox.com/?p=pve-kernel-3.10.0.git;
we nethertheless need the iscsitarget module as there seems to be a
bug in the dkms module which we had to fix manually.

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

I'm not sure, but wouldn't it make sense to give the 3.19.8 pve kernel a

Best regards,

>> ---------------->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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