[OmniOS-discuss] The ixgbe driver, Lindsay Lohan, and the Greek economy
W Verb
wverb73 at gmail.com
Mon Feb 23 01:54:58 UTC 2015
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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