LHC@home

Hello all,

The issue preventing the AVX executable from being distributed has finally been found and resolved.

If your computer has AVX support, you should now be sent the AVX executable. This may take a short while to stabilise.

If you think you should be sent the AVX executable and this is not happening, please comment below.

I have the AVX application (and tasks) on two hosts now but so far can't tell how much faster it is. One task took 5 seconds and another 2h 48 minutes. The other host hasn't started using it yet.

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Seem good for me too, all my computers have switched to using AVX except my old Mac Pro which doesn't have AVX

Host 10519008 (hidden) is a 64-bit CentOS running on a Qemu/KVM host. AVX is listed in Boinc's Processor features, and should be exposed by the host. FWIW it just received 2 SSE2 SixTrack tasks.

/dda

My i7-3770 machine (Ubuntu 16.04) has downloaded two batches since the release of the AVX work units.
But it has gotten only the SSE2 work units.
https://lhcathome.cern.ch/lhcathome/results.php?hostid=10502606

(My Ryzen 1700 has gotten the AVX though).

Yes it is a bit strange, but let's give BOINC a bit more time to learn and explore avx exes on your machine before tackling the issue
Thanks!

Under normal circumstances the BOINC server will send out all app types a client can run and measures their performance.
See "Computers on this account" -> "Details" -> "Application details" from your main account page.

Once the numbers have settled the server will send mostly the app with the best performance, except for periodical retesting.

As the tests can be influenced by various parameters on the client side as well as on the server side you may get an app that may (nominally) be slower, e.g. sse2 instead of avx.
This occurs especially if the performance numbers are very close together.
On the other hand it would not result in a performance boost if you get the "right" app in this case.

It would only be suspicious if you permanently get a much slower app.

@computezrmle: thanks for the thorough clarification, sounds very logical.

I just, out of curiosity, downloaded a few Sixtrack tasks on the one PC with AVX capibilities, but - as expected - SSE2 tasks came in.

Hello all,

The issue preventing the AVX executable from being distributed has finally been found and resolved.

If your computer has AVX support, you should now be sent the AVX executable. This may take a short while to stabilise.

If you think you should be sent the AVX executable and this is not happening, please comment below.

So far, I have not received a single task with AVX executable for the PC with AVX support. Things still seem to go wrong.

How can I STOP getting these AVX tasks?

I want other members to have hundreds of these that finish in 7 seconds just like they did in 2004
I prefer tasks that actually run for a few hours otherwise I have to set the 8-core computers running set to always receive more tasks which of course make me end up with hundreds of tasks that can't be finished on time.

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Volunteer Mad Scientist For Life

How can I STOP getting these AVX tasks?

you lucky guy - I would very much like to get AVX tasks, but I do not receive any.

BTW, trying to find out what could be the reason for not receiving AVX tasks, a search in the web seems to indicate that in order to make the AVX extension work, there needs to be the AVX.dll in the "Windows\System32" folder, and for 64-bit systems (like in my case) also in the "Windows\sysWOW64" folder.
I checked all my PCs (Windows10 and WindowsXP, all 64-bit), in none of them the avx.dll shows up.

I wonder if it is really necessary to install this avx.dll by hand - can anyone tell me more?

@Magic, that how the sixtrack tasks work, if the calculations aren't stable then it will be short task, I see a mix of long and short tasks as per normal for sixtrack. I scheduler probally needs some more time to create the correct buffer although with the nature of six tract that is tough too. Maybe you can edit a config file to spoof that you don't have avx?

@Erich, on my windows 10 computer I don't see this avx dll and have crunched many WU, so I don't think that is the problem. What do you see under [---] Processor features: on startup?

On my i5-6500 system I received several AVX tasks a couple of days ago.
The application details show:

SixTrack 46.30 windows_x86_64 (sse2)

Number of tasks completed 958
Consecutive valid tasks 411
Average processing rate 15.29 GFLOPS

SixTrack 46.30 windows_x86_64 (avx):

Number of tasks completed 1
Consecutive valid tasks 3
Average processing rate 59.42 GFLOPS

As the average processing rate for the AVX tasks is higher I would expect to be receiving more AVX work, but since the initial couple of tasks I am receiving only SSE2 tasks again. Does this make sense ?

Tom

I think I had 2 similar tasks. One ran with sse2 and the other with avx support.

w-c1_job.B1inj_c1.2158__31__s__64.28_59.31__9.1_10.1__6__76.5_1_sixvf_boinc32325_1
173087412 83941338 19 Jan 2018, 15:54:55 UTC 20 Jan 2018, 7:32:36 UTC Voltooid en gecontroleerd 16,684.31 16,613.84 90.77 SixTrack v46.30 (sse2) windows_intelx86

Task w-c1_job.B1inj_c1.2158__30__s__64.28_59.31__5.1_6.1__6__88.5_1_sixvf_boinc31035_0
173084757 83939990 19 Jan 2018, 15:32:49 UTC 19 Jan 2018, 20:59:45 UTC Voltooid en gecontroleerd 15,421.92 15,322.79 127.84 SixTrack v46.30 (avx) windows_x86_64

I know Sixtrack tasks are hardly to compare, but I think they were similar and the avx-executable seems about 8% faster.

To compare sse2 with avx run both apps locally with the same input file.
Ideally under the same global prerequisits, i.e. total load, project mix ...

Only this will show if avx is faster on this particular computer or not.

@Erich56:
I am not an expert in how BOINC decides which version to send to volunteers and the algorithm behind, but indeed I see that BOINC has never tried even once to send an AVX executable, eg (I picked up your Windows 10 machine):
https://lhcathome.cern.ch/lhcathome/host_app_versions.php?hostid=10450564&show_dep=1
I have no experience with that, but maybe you could also try to run the benchmark application.

@Crystal Pellet:
From our internal tests, we saw ~25% improvements by avx compared to sse2. I will let James comment more in details.

Thanks!
A.

BTW, trying to find out what could be the reason for not receiving AVX tasks, a search in the web seems to indicate that in order to make the AVX extension work, there needs to be the AVX.dll in the "Windows\System32" folder, and for 64-bit systems (like in my case) also in the "Windows\sysWOW64" folder.
I checked all my PCs (Windows10 and WindowsXP, all 64-bit), in none of them the avx.dll shows up.
I wonder if it is really necessary to install this avx.dll by hand - can anyone tell me more?

I now restarted BOINC, and in the event log, under processor features, AVX is indeed not listed:

20/01/2018 15:33:47 | | Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss htt tm pni ssse3 cx16 sse4_1 sse4_2 popcnt aes f16c rdrandsyscall nx lm vmx tm2 dca pbe fsgsbase smep

This is strange. Because my Intel i7-4930k definitely supports AVX, this is also shown in CPU-Z.

So would it really be necessary to install and register the AVX.dll by hand? Did anyone of those crunchers who received AVX-tasks need to do that?

Check your BIOS settings first. Maybe it was disabled by some auto-tuning feature?

Does CPU-Z show features available in general or features active on the actual system?

To compare sse2 with avx run both apps locally with the same input file.

@computezrmle I've been wondering, is there an "easy" way to do this? Any tutorials you know of?

Check your BIOS settings first. Maybe it was disabled by some auto-tuning feature?

Too bad that I have started several VM tasks now, which I don't want to interrupt, as they will probably fail.

Does CPU-Z show features available in general or features active on the actual system?

Good question - I honestly don't know. Would need to find out somewhere.