[OmniOS-discuss] The ixgbe driver, Lindsay Lohan, and the Greek economy
Chris Nagele
nagele at wildbit.com
Mon Feb 23 04:37:46 UTC 2015
Is the issue here only related to iSCSI? We've used the X520's for NFS
for a couple of years and it has worked really well for us.
Not sure if this is an accurate test, but iperf shows the following
results for me:
Over 1GbE:
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 981 MBytes 823 Mbits/sec
Over 10GbE on the same machines:
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 9.42 GBytes 8.09 Gbits/sec
I could be going in the wrong direction here, but I was curious as
well since we rely on 10G heavily.
Chris
On Sun, Feb 22, 2015 at 8:54 PM, W Verb <wverb73 at gmail.com> wrote:
> By the way, to those of you who have working setups: please send me
> your pool/volume settings, interface linkprops, and any kernel tuning
> parameters you may have set.
>
> Thanks,
> Warren V
>
> On Sat, Feb 21, 2015 at 7:59 AM, Schweiss, Chip <chip at innovates.com> wrote:
>> I can't say I totally agree with your performance assessment. I run Intel
>> X520 in all my OmniOS boxes.
>>
>> Here is a capture of nfssvrtop I made while running many storage vMotions
>> between two OmniOS boxes hosting NFS datastores. This is a 10 host VMware
>> cluster. Both OmniOS boxes are dual 10G connected with copper twin-ax to
>> the in rack Nexus 5010.
>>
>> VMware does 100% sync writes, I use ZeusRAM SSDs for log devices.
>>
>> -Chip
>>
>> 2014 Apr 24 08:05:51, load: 12.64, read: 17330243 KB, swrite: 15985 KB,
>> awrite: 1875455 KB
>>
>> Ver Client NFSOPS Reads SWrites AWrites Commits Rd_bw
>> SWr_bw AWr_bw Rd_t SWr_t AWr_t Com_t Align%
>>
>> 4 10.28.17.105 0 0 0 0 0 0
>> 0 0 0 0 0 0 0
>>
>> 4 10.28.17.215 0 0 0 0 0 0
>> 0 0 0 0 0 0 0
>>
>> 4 10.28.17.213 0 0 0 0 0 0
>> 0 0 0 0 0 0 0
>>
>> 4 10.28.16.151 0 0 0 0 0 0
>> 0 0 0 0 0 0 0
>>
>> 4 all 1 0 0 0 0 0
>> 0 0 0 0 0 0 0
>>
>> 3 10.28.16.175 3 0 3 0 0 1
>> 11 0 4806 48 0 0 85
>>
>> 3 10.28.16.183 6 0 6 0 0 3
>> 162 0 549 124 0 0 73
>>
>> 3 10.28.16.180 11 0 10 0 0 3
>> 27 0 776 89 0 0 67
>>
>> 3 10.28.16.176 28 2 26 0 0 10
>> 405 0 2572 198 0 0 100
>>
>> 3 10.28.16.178 4606 4602 4 0 0 294534
>> 3 0 723 49 0 0 99
>>
>> 3 10.28.16.179 4905 4879 26 0 0 312208
>> 311 0 735 271 0 0 99
>>
>> 3 10.28.16.181 5515 5502 13 0 0 352107
>> 77 0 89 87 0 0 99
>>
>> 3 10.28.16.184 12095 12059 10 0 0 763014
>> 39 0 249 147 0 0 99
>>
>> 3 10.28.58.1 15401 6040 116 6354 53 191605
>> 474 202346 192 96 144 83 99
>>
>> 3 all 42574 33086 217 6354 53 1913488
>> 1582 202300 348 138 153 105 99
>>
>>
>>
>>
>>
>> On Fri, Feb 20, 2015 at 11:46 PM, W Verb <wverb73 at gmail.com> wrote:
>>>
>>> Hello All,
>>>
>>> Thank you for your replies.
>>> I tried a few things, and found the following:
>>>
>>> 1: Disabling hyperthreading support in the BIOS drops performance overall
>>> by a factor of 4.
>>> 2: Disabling VT support also seems to have some effect, although it
>>> appears to be minor. But this has the amusing side effect of fixing the
>>> hangs I've been experiencing with fast reboot. Probably by disabling kvm.
>>> 3: The performance tests are a bit tricky to quantify because of caching
>>> effects. In fact, I'm not entirely sure what is happening here. It's just
>>> best to describe what I'm seeing:
>>>
>>> The commands I'm using to test are
>>> dd if=/dev/zero of=./test.dd bs=2M count=5000
>>> dd of=/dev/null if=./test.dd bs=2M count=5000
>>> The host vm is running Centos 6.6, and has the latest vmtools installed.
>>> There is a host cache on an SSD local to the host that is also in place.
>>> Disabling the host cache didn't immediately have an effect as far as I could
>>> see.
>>>
>>> The host MTU set to 3000 on all iSCSI interfaces for all tests.
>>>
>>> Test 1: Right after reboot, with an ixgbe MTU of 9000, the write test
>>> yields an average speed over three tests of 137MB/s. The read test yields an
>>> average over three tests of 5MB/s.
>>>
>>> Test 2: After setting "ifconfig ixgbe0 mtu 3000", the write tests yield
>>> 140MB/s, and the read tests yield 53MB/s. It's important to note here that
>>> if I cut the read test short at only 2-3GB, I get results upwards of
>>> 350MB/s, which I assume is local cache-related distortion.
>>>
>>> Test 3: MTU of 1500. Read tests are up to 156 MB/s. Write tests yield
>>> about 142MB/s.
>>> Test 4: MTU of 1000: Read test at 182MB/s.
>>> Test 5: MTU of 900: Read test at 130 MB/s.
>>> Test 6: MTU of 1000: Read test at 160MB/s. Write tests are now
>>> consistently at about 300MB/s.
>>> Test 7: MTU of 1200: Read test at 124MB/s.
>>> Test 8: MTU of 1000: Read test at 161MB/s. Write at 261MB/s.
>>>
>>> A few final notes:
>>> L1ARC grabs about 10GB of RAM during the tests, so there's definitely some
>>> read caching going on.
>>> The write operations are easier to observe with iostat, and I'm seeing io
>>> rates that closely correlate with the network write speeds.
>>>
>>>
>>> Chris, thanks for your specific details. I'd appreciate it if you could
>>> tell me which copper NIC you tried, as well as to pass on the iSCSI tuning
>>> parameters.
>>>
>>> I've ordered an Intel EXPX9502AFXSR, which uses the 82598 chip instead of
>>> the 82599 in the X520. If I get similar results with my fiber transcievers,
>>> I'll see if I can get a hold of copper ones.
>>>
>>> But I should mention that I did indeed look at PHY/MAC error rates, and
>>> they are nil.
>>>
>>> -Warren V
>>>
>>> On Fri, Feb 20, 2015 at 7:25 PM, Chris Siebenmann <cks at cs.toronto.edu>
>>> wrote:
>>>>
>>>> > After installation and configuration, I observed all kinds of bad
>>>> > behavior
>>>> > in the network traffic between the hosts and the server. All of this
>>>> > bad
>>>> > behavior is traced to the ixgbe driver on the storage server. Without
>>>> > going
>>>> > into the full troubleshooting process, here are my takeaways:
>>>> [...]
>>>>
>>>> For what it's worth, we managed to achieve much better line rates on
>>>> copper 10G ixgbe hardware of various descriptions between OmniOS
>>>> and CentOS 7 (I don't think we ever tested OmniOS to OmniOS). I don't
>>>> believe OmniOS could do TCP at full line rate but I think we managed 700+
>>>> Mbytes/sec on both transmit and receive and we got basically disk-limited
>>>> speeds with iSCSI (across multiple disks on multi-disk mirrored pools,
>>>> OmniOS iSCSI initiator, Linux iSCSI targets).
>>>>
>>>> I don't believe we did any specific kernel tuning (and in fact some of
>>>> our attempts to fiddle ixgbe driver parameters blew up in our face).
>>>> We did tune iSCSI connection parameters to increase various buffer
>>>> sizes so that ZFS could do even large single operations in single iSCSI
>>>> transactions. (More details available if people are interested.)
>>>>
>>>> > 10: At the wire level, the speed problems are clearly due to pauses in
>>>> > response time by omnios. At 9000 byte frame sizes, I see a good number
>>>> > of duplicate ACKs and fast retransmits during read operations (when
>>>> > omnios is transmitting). But below about a 4100-byte MTU on omnios
>>>> > (which seems to correlate to 4096-byte iSCSI block transfers), the
>>>> > transmission errors fade away and we only see the transmission pause
>>>> > problem.
>>>>
>>>> This is what really attracted my attention. In our OmniOS setup, our
>>>> specific Intel hardware had ixgbe driver issues that could cause
>>>> activity stalls during once-a-second link heartbeat checks. This
>>>> obviously had an effect at the TCP and iSCSI layers. My initial message
>>>> to illumos-developer sparked a potentially interesting discussion:
>>>>
>>>>
>>>> http://www.listbox.com/member/archive/182179/2014/10/sort/time_rev/page/16/entry/6:405/20141003125035:6357079A-4B1D-11E4-A39C-D534381BA44D/
>>>>
>>>> If you think this is a possibility in your setup, I've put the DTrace
>>>> script I used to hunt for this up on the web:
>>>>
>>>> http://www.cs.toronto.edu/~cks/src/omnios-ixgbe/ixgbe_delay.d
>>>>
>>>> This isn't the only potential source of driver stalls by any means, it's
>>>> just the one I found. You may also want to look at lockstat in general,
>>>> as information it reported is what led us to look specifically at the
>>>> ixgbe code here.
>>>>
>>>> (If you suspect kernel/driver issues, lockstat combined with kernel
>>>> source is a really excellent resource.)
>>>>
>>>> - cks
>>>
>>>
>>>
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>>>
>>
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