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Re: [Xen-devel] NFS related netback hang

>> I still believe the key factor is to stress the memory.
>> Maybe you can try further limit the memory size and use a larger file size.
>> I become uncertain about how the transfer speed affects.
>> I can achieve 10GB/s in iperf test without issue.
>> And ftp transfer also works without problem at 50MB/s
>> But may be the higher net speed is a negative factor here -- NFS may
>> be able to commit changes in faster speed.
>> Probably we should feed data faster than NFS can handle so that memory
>> is used up quickly?
>> But the back pressure from down stream should slow down the speed that
>> upstream is eating the memory.
>> How does the throttling works? Anyway to control?
>> I'll check why my dom0 reported OOM, may be that's one factor too.
> This is a good starting point. :-)

It seems that the OOM-killer was only triggered on kernel version 3.6.9.
It does not show up in 3.6.11 while the issue still exists.
So I guess there are some changes in mm behavior in recent kernels.
Probably I should try with your kernel version.

But anyway, let's see some existing data first.
Please find the full oom_kill log in the attached file.
It seems that OOM_KILL is caused by the freeze issue, since the NFS
server (domU) becomes unresponsive first.
There are about 900MB dirty pages. (writeback:152893 unstable:72860,
can they be simply added?)
I don't remember the totoal memory at that time due to the ballooning.
The total DRAM in the host is 8GB.


Attachment: oom_kill
Description: Binary data

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