VirtualBox, Windows Guest Virtual Machines, and The VirtIO Network Interface

 Computing, Working Notes  No Responses »
Apr 302017
 

Despite how long I have been running Windows in virtual machines (as far back as Vmware Workstation 1.0), I have never gotten around to looking at the virtio network interface – except for naïvely turning it on once, finding it didn’t work, and turning it off – so I decided to have a look at it. I was prompted to do this by a suggestion that emulating the NIC hardware as opposed to simply using a virtual communications channel to the host would hurt network performance. Good job I chose a long weekend because I ran into a few issues :-

  • Getting appropriate test tools took a while because most of the tools I know of are very old; I ended up using iperf2 on both the Linux main host and the Windows 10 guest (within the “Windows
  • The “stable” virtio drivers (also called “NetKVM”) drivers didn’t work. Specifically they could send packets but not receive them (judging from the DORA conversation that was more of a DODO). I installed the “latest” drivers from https://fedoraproject.org/wiki/Windows_Virtio_Drivers. Note to late readers: this was as of 2017-04-30; different versions may offer different results.
  • Upgrading my ancient Debian Jessie kernel to 4.9 on the off-chance it was a kernel bug turned into a bit of an exercise what with ZFS disappearing after the upgrade, and sorting out the package dependencies to get it re-installed was “interesting” (for small values of course). No data loss though.

I ran two tests :-

  1. sudo nping –tcp -p 445 –count 200 –data-len 1280 ${ip of windows guest) – to judge how reliable the network connection was.
  2. On the Linux host: sudo iperf -p 50001 
  3. On the Windows guest (from within the Ubuntu-based environment): sudo iperf -p 50001 -c ${ip of Linux host}
Device nping result iperf result
Windows guest (virtual Intel Pro 1000 MT Desktop 1 lost 416 Mbits/sec
Windows guest (virtio) 0 lost 164 Mbits/sec
CuBox running ARM Linux n/a 425 Mbits/sec

Which is not the result I was expecting. And yes I did repeat the tests a number of times (I’ve cheated and chosen the best numbers for the above table), and no I did not confuse which NIC was configured at the time of the tests nor did I get the tests mixed up. And to those who claim that the use of the Ubuntu environment screwed things up, that appears not to be the case – I repeated the test with a Windows compiled version of iperf with much the same results.

So it seems despite common sense indicating that a NIC “hardware” custom designed for a virtual environment should perform better than an emulation of a hardware NIC, the actual result in this case was the other way around. Except for the nping result which shows the loss of a single packet with the emulated hardware NIC.

May for the Neo-Führer?

 Politics  No Responses »
Apr 222017
 

May continue to cut public sector salaries year on year.

May continue to pillage the public services we all use to pay for the bankers mistakes.

May continue to make tax cuts for the rich.

May continue to cut welfare payments to the poorest families in our society causing a huge increase in child poverty.

May continue to stumble and fumble around during the Brexit negotiations in all likelihood resulting in a poor deal for Britain.

May continue to antagonise the non-English countries of the union increasing the likelihood of a break-up.

May continue to add powers to the secret policemen until we’re living in a police state (hint: it’s not that far off).

Time to look past May to June and choosing anyone other than May.

How Long Would It Take To Empty The Oceans With A Teaspoon?

 General, Humour  2 Responses »
Apr 202017
 

Today I pointed out that persuading teenagers to stop thinking “filthy” thoughts is roughly comparable to the task of emptying the ocean with a teaspoon, and someone retorted that the later was possible. Well perhaps, but until we’ve worked out a rough calculation we don’t really know do we?

And yes I am weird enough to have gone ahead and worked it out.

 

 

Swirling Sea

According to the wonder that is Wikipedia, the average teaspoon can contain approximately 5ml of liquid – not often ocean but the type of liquid is irrelevant.

According to a handy table, there are approximately 1.3 billion square kilometres of water in the world’s oceans. And according to a handy units calculator this equates to 1.3e21 litres of water. Dividing this figure by the volume of our teaspoon, we get the value 2.6e+23 teaspoons of water in the ocean.

Assuming that it takes 10s (we could argue about how accurate that is, but trust me it doesn’t make too much of a difference to the final conclusion) to move a teaspoon of seawater into a truly ginormous container that magically appears to contain it all, it will take approximately 2.6e+24 seconds to empty the oceans.

Now you could work on this non-stop, but I’m no Victorian factory owner, so I will be assuming an 8-hour working day, and a 5 day working week. Admittedly no paid holiday (you want pay for this? I don’t think so).

So dividing the stupendously large number of seconds by 60 (to get minutes) by 60 (to get hours) by 8 (to get days) by 5 (to get weeks) by 52 (to get years) we get approximately 3.5e+17 years. Good! We’ve reduced the E numbers somewhat!

Now if we divide this number of years by the expected lifetime of the sun (10 billion years – and ignoring the fact that we’re approximately half-way through the sun’s lifetime), we get a much more manageable figure of 34,722,222 sun lifetimes.

However it is not unreasonable to assume that something will happen to the oceans before we get anywhere near completing this little task.

Breakfast Neglects To Mention William’s Cause: Male Suicide

 General  No Responses »
Apr 182017
 

BBC Breakfast had a story this morning covering Prince William’s struggle with mental health, together with an interview with a counsellor and a mental health patient (both women – and this becomes relevant shortly). All very interesting and worthwhile – those with problems should be encouraged to seek assistance.

Yet what was missing?

The fact that William went public about his need for counselling in support of CALM which is an organisation trying to do something useful about the level of suicide amongst young men.

Whilst generalising the short piece to encourage everyone who needs help to seek it, it seems odd that the mysteriously high rate of suicide amongst young men and CALMs efforts to tackle it should really have gotten a mention.

 

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