[kernel-xen] kernel-xen-3.11.0-1 in testing repo.
netwiz at crc.id.au
Sun Sep 22 17:58:41 EST 2013
On 17/09/2013 12:05 PM, Glenn Enright wrote:
> On 09/17/13 13:56, Steven Haigh wrote:
>> On 17/09/13 11:30, Glenn Enright wrote:
>>> 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
>>> dd if=/dev/zero of=speedtest bs=1M count=1024 conv=fsync
>>> 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
>> This is good to see. I'd actually expect a bit more than that - but
>> either way, its good to see an increase in throughput. What actual
>> drives are these? I use Seagate 1Tb 7200rpm SATA drives in my home test
>> setup - but I haven't done a throughput test on the RAID1 as yet - as it
>> hasn't really been problematic in the past.
>> There is talk around this having a way to automatically do a test and
>> set xen-blkfront.max to an optimal value on initialisation of the DomU
>> blkfront module. As yet, this is only talk - however it would probably
>> be a good step forwards.
>> It may even get to the point where it could be backported into distro
>> kernels - and therefore not require the upgrade to 3.11 on the DomU to
>> take advantage of this - however that would be a job for various distros.
> The drives are pair of WD RE3 250G, nothing special there.
> I managed to get the write result up to about 72MB/s average by tweaking
> the read ahead buffer for the raid1. Thats probably about as good as it
> gets given the host OS gets no more than 78Mb/s average on the same pair.
> As time permits I'll try with some different numbers and test raid6 and
> as well.
For what its worth, I've been updating some of my DomU's to the 3.11.1
kernel as well. Currently defining a backup volume to an eSATA drive via
eSATA caddy. It's a single drive:
Model Family: Seagate Barracuda 7200.12
Device Model: ST31000524AS
Serial Number: 6VP9DWVG
LU WWN Device Id: 5 000c50 03ce3905c
Firmware Version: JC4B
User Capacity: 1,000,204,886,016 bytes [1.00 TB]
Results via iostat (cutting the header each time):
# iostat sdg -m 5 10
Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sdg 762.81 0.00 96.50 0 433
sdg 787.25 0.00 98.36 0 439
sdg 737.69 0.00 93.40 0 421
sdg 763.92 0.00 96.67 0 434
sdg 741.56 0.00 93.87 0 422
sdg 732.07 0.00 92.66 0 416
sdg 756.12 0.00 95.70 0 429
This is substantially faster than what I was getting with the stock EL6
kernels. The other good news is that this particular DomU has drives
added/removed via scripts - and I don't get any kernel oops messages now ;)
Email: netwiz at crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
Fax: (03) 8338 0299
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