[kernel-xen] kernel-xen-3.11.0-1 in testing repo.

[Glenn Enright]

Preliminary (very) testing seems to indicate a good boost (using 3.11.1)

Seeing about a 20% increase on buffered writes, and a small but marked 
increase on syncronised writes. Which is nice. Keep in mind this is on 
an unloaded host with only a couple of VMs.

In detail ...

I'm working on a machine with VMs backed by lvm disk over raid1 (using 
budget sata drives), with the following snippet, with and without the 
fsync option. The test domU uses the noop scheduler.

for i in 1 2 3 4 5
do
   dd if=/dev/zero of=speedtest bs=1M count=1024 conv=fsync
done

3.10 domO, default behavour, custom domu kernel
using fsync average 58 MB/s, without fsync average 59 MB/s,

3.11 domO, default behaviour, 3.11 kernel on domu
using fsync average 58 MB/s (ie the same)

3.11 domO, using xen-blkfront.max=128, 3.11 kernel on domU
using fsync average 62 MB/s, without fsync average 68 MB/s


On 09/07/13 19:46, Steven Haigh wrote:
> On 06/09/13 10:10, Steven Haigh wrote:
>> On 05/09/13 21:22, Gordan Bobic wrote:
>>> On Thu, 05 Sep 2013 21:14:49 +1000, Steven Haigh <netwiz at crc.id.au> wrote:
>>>> On 05/09/13 20:54, Gordan Bobic wrote:
>>>>> On Thu, 05 Sep 2013 15:37:31 +1000, Steven Haigh <netwiz at crc.id.au>
>>>>> wrote:
>>>>>> Hi all,
>>>>>>
>>>>>> I've built kernel 3.11.0 and placed it in the testing repo. Major
>>>>>> changes include optimisations on both the network stack and disk
>>>>>> subsystem.
>
> For those curious, I'd been having a long standing issue where I
> couldn't get more than ~50Mb/sec to an underlying RAID6 array.
>
> Using this testing kernel on both the DomU and Dom0, then adding
> xen-blkfront.max=128 to the kernel line of the DomU has managed to give
> over 100Mb/sec of sustained writes to the same RAID6 - just about
> doubling write speed to the array.
>
> If anyone else comes across similar performance bottlenecks, I'd love to
> hear if the above helps out...
>
>
>
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