jason_gee 的帖子

141) 留言板 : Number crunching : Linux CUDA 'Special' App finally available, featuring Low CPU use (消息 1849506)
发表于:18 Feb 2017 作者: Profile jason_gee
Post:
out of curiosity, which programming language are people using to create their own special apps? is it a matter of improving code or optimizing during compiling?


Primarily hand coded optimisations in both the GPU Cuda/OpenCL and Host CPU C/C++ code. In the case of Cuda special apps, that tends to be a combination of higher level structural optimisations, such as adapting to use Cuda Streams, along with low level PTX assembly (&/or intrinsics). The higher level structural enhancements tend to allow better scaling on newer hardware, while the low level assembly tends to improve memory access patterns and instruction level paralellism. Compiler options tended to decrease in importance after about Cuda 4, since nVidia switched to an LLVM based compiler. That relatively modern type of compiler tends to do a reasonable job without much twiddling.
142) 留言板 : Number crunching : Back to 99% GPU's? (消息 1849333)
发表于:17 Feb 2017 作者: Profile jason_gee
Post:

So the next question is what can I do to raise the GPU loading (and presumably speed up the Cuda 50 processing?).


[Edit:] Note, in addition to below suggestions, you may also be getting 'Shorty' (Very High Angle Range Arecibo ) tasks, which can present a lower load naturally.

Normally I would suggest a couple of instances for cuda apps, though with 750/750ti, single instance Cuda50 should be enough. So your guess of trying the processpriority key will probably help somewhat. Aside from that, any background applications such as the network streaming fruit and telemetry/diagnostics present with newer drivers [and GeForce Experience] can impact that loading under Cuda. There are guides around on the internet for disabling much bloat there. The reasons OpenCL should be less impacted there would be that OpenCL is wired in at a lower level than cuda, and is written to 'spread' more anyway. Probably future applications will have some more intuitive loading controls (and similarly conservative defaults), but for now getting the best out a particular GPU can be a matter of trial and error.
143) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1848776)
发表于:15 Feb 2017 作者: Profile jason_gee
Post:
20. The End-of-file (EOF) check may not be
enough
...
On top of that, incorrect data will be processed in the loop, as unknown values
will be getting to the tmp variable.
To avoid issues like that, we need to use additional methods to check the stream status:
bad(), fail().
...

Interesting. Wonder if that could also be an explanation for tapes that when failing end up with end channels full of errors?


With codebases so complex, it'd certainly be one possibility of many. The code resides in a utility library set of functions probably used by all the servers, it could certainly account for some amount of fragility under stress. Either way, refactoring to harden this won't hurt.
144) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1848774)
发表于:15 Feb 2017 作者: Profile jason_gee
Post:
Possibly apropos to the mentions of stuck tapes, I stumbled on this gem while researching for my own refactoring endeavours. This example points out one possible infinite loop, that can be triggered when there is some minor glitch, in some of Seti's file handling code. Forwarding details to Eric.

From The Ultimate Question of Programming, Refactoring, and Everything

20. The End-of-file (EOF) check may not be
enough
The fragment is taken from SETI@home project. The error is detected by the following PVSStudio
diagnostic: V663 Infinite loop is possible. The 'cin.eof()' condition is insufficient to
break from the loop. Consider adding the 'cin.fail()' function call to the conditional
expression.
...
Explanation
The operation of reading data from a stream object is not as trivial as it may seem at first.
When reading data from streams, programmers usually call the eof() method to check if the
end of stream has been reached. This check, however, is not quite adequate as it is not
sufficient and doesn't allow you to find out if any data reading errors or stream integrity
failures have occurred, which may cause certain issues.
Note. The information provided in this article concerns both input and output streams. To
avoid repetition, we'll only discuss one type of stream here.
This is exactly the mistake the programmer made in the code sample above: in the case of
there being any data reading error, an infinite loop may occur as the eof() method will always
return false. On top of that, incorrect data will be processed in the loop, as unknown values
will be getting to the tmp variable.
To avoid issues like that, we need to use additional methods to check the stream status:
bad(), fail().
...
145) 留言板 : Number crunching : CES 2017 -- AMD RYZEN CPU (消息 1848281)
发表于:12 Feb 2017 作者: Profile jason_gee
Post:
From the PCper architectural details, given on their last podcast, the half clocked AVX256 might be something to consider for many. For our purposes mostly feeding GPUs, I think/hope that'll be much of a muchness. Had to be a compromise. Pretty sure I could live with half speed AVX256 at the price and power advantages over the equivalent Intels. We'll see.
146) 留言板 : Number crunching : I've Built a Couple OSX CUDA Apps... (消息 1848088)
发表于:11 Feb 2017 作者: Profile jason_gee
Post:
Still nothing new on the nVidia Special App. At present the OSX version is still producing twice as many Inconclusive results as the Linux version.


Should be able to do a little more poking once the ambient daytime temps drop below 40 Celcius. At that point will temporarily switch the GTX 780 back in, and try for parallel Linux and OSX builds against baseline. If Petri's last contributions improve what was in alpha, I'll wedge in some comparison code for isolating the differences. There are some simple options to try if races are still present. Will know more later in the week.
147) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1847916)
发表于:11 Feb 2017 作者: Profile jason_gee
Post:
Stocked up the Linux host, and seem to only get a couple of GBT tasks. Looks like mostly Arecibo shorties
148) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1847810)
发表于:10 Feb 2017 作者: Profile jason_gee
Post:
OH, STOP IT.
It was reported that the unrest on the Berkeley campus that night was instigated by a group from outside of either the university or it's students.

Oh, meow on you.

And this thread is about server problems.
If you wish to talk politics, go to that forum.

Meowgrowwwwwwwwwwwwwwwwwwwwllllll.

BTW, I like the splitter mix now...............
PFB splitters full on deck and GBT too.


Mark, It's simple. Berkeley has allowed terrorists onto their campus, and trained them. If you think that's OK then that would make you a terrorist.
149) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1847738)
发表于:10 Feb 2017 作者: Profile jason_gee
Post:
When push comes to shove I hope Berkeley has the sense to expel all staff and students involved in instigating the violence.


I doubt anything will be done. As of today only 1 person was arrested the night of the riot. 2 other were arrested the next morning but nothing specific on why. There is only 1 employee under "investigation" as he posted his involvement on social media along with pics. But I doubt much will come of it. In fact, it's hard to anything anymore in the news about it.


If it goes that way, that is in violation of the US constitution , then the university will dissolve. Slowly but surely. It is the tenets of free speech that Berkeley became great. By blocking them to protect broken ideologies, then they become the enemy.
150) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1847728)
发表于:10 Feb 2017 作者: Profile jason_gee
Post:
No the opposite if you had. The minions are out and about fiddling with stuff for revenge. More to the point can you prove it isn't hillary or Obama, or their minions, interfering with your flow ?


First thing that went thru my mind when I saw they were starting fires and smashing windows on Campus last week. I had to wonder where on Berkeley the Seti offices were and where the servers were located. Second was glad it was at night and hopefully none of the staff was on campus.


Ran through my mind as well. By my understanding the SSL component at least is way up a hill, so no pasty dweebs are going to be running there with molotov cocktails anytime soon. To me, as a classical centre-liberal, it's just depressing that money and failed socialist intolerant/bigoted agendas can hurt hard working people. When push comes to shove I hope Berkeley has the sense to expel all staff and students involved in instigating the violence.
151) 留言板 : Number crunching : What ever happened to CUDA 50/42/etc (消息 1847679)
发表于:10 Feb 2017 作者: Profile jason_gee
Post:
...So many of the older units out there could not run it which is one stumbling block on getting into main. But for everyone else ... :


Yep, confirmed. A few other lesser problems to iron out over time. My own input is minimal at the moment, mostly due to a spate of home things to deal with, and 40C temps. Will get there eventually.
152) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1847548)
发表于:9 Feb 2017 作者: Profile jason_gee
Post:

. . ATM I am getting "No tasks available" constantly across the three machines :(

. . Not looking good.

Stephen

:(


Did you say something bad about Obama or Hillary ?


. . Not at all, should I have? Would that appease the great god Trump and get me more work??

Stephen

:)


No the opposite if you had. The minions are out and about fiddling with stuff for revenge. More to the point can you prove it isn't hillary or Obama, or their minions, interfering with your flow ?
153) 留言板 : Number crunching : Linux (ARM processor) app and alternatives (消息 1847515)
发表于:9 Feb 2017 作者: Profile jason_gee
Post:
At this rate I estimate ARM may overtake x86/x86_64 within 3 years :D
154) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1847509)
发表于:9 Feb 2017 作者: Profile jason_gee
Post:
Looks like we're almost out of GBT data. Splitter output dropping off again, Ready to send buffer is making it's way back down to 0.

EDIT-
And the only Arecibo work I've got since the re-introduction of Guppies have been resends. Not a single recently split WU.


. . ATM I am getting "No tasks available" constantly across the three machines :(

. . Not looking good.

Stephen

:(


Did you say something bad about Obama or Hillary ?
155) 留言板 : Number crunching : CES 2017 -- AMD RYZEN CPU (消息 1847179)
发表于:7 Feb 2017 作者: Profile jason_gee
Post:
With virtualisation hardware passthrough likely maturing on nerd to consumer level, at the same time as a lot of these basic kernel and programming model changes, A viable alternative for larger crunchers could well be a slim Linux OS, hosting other OS virtual machines as needed. In the context of Ryzen or newer gen Intel 'support', it probably will amount to that only the choice of host OS matters, but you may well use whatever you like for daily driving or crunching.
156) 留言板 : Number crunching : Recommendations For A Game Monitor? (消息 1846822)
发表于:5 Feb 2017 作者: Profile jason_gee
Post:
If it were me , I would try to wait a bit if you can, because there seems to be a technology war on the monitor market, which will only drive prices and choices for the better.(And I am waiting a bit)

The tradeoff has been speed/response versus colour accuracy, but that's changing on the most expensive end.

In my experience:
-> Switched to 120Hz, low ms, some years ago and never looked back. Was competitively gaming at the time, and it made a big difference. -> Beyond 120 Hz the improvement isn't so noticeable.
-> 1440p IMO would be current sweet spot indeed. 4k is too much to drive smoothly, and 1080p starting to look old.
-> Gsync would only be necessary if you want tear free on games that will load the system heavily

If you had to buy now, I'd probably recommend the Acer Predator XB271HU . I don't own one, but used one on a 3 day visit to a friend's house. It's more or less perfect unless you need to do art/media. Probably the next generation will base specs off that as minimum.
157) 留言板 : Number crunching : Mac OS Sierra (消息 1844954)
发表于:28 Jan 2017 作者: Profile jason_gee
Post:
My question would be why are you concerned?
I don't have an OSX Intel iGPU, but neither does Urs or Raistmer. You don't seem to be bothered by Raistmer or Urs "playing around with apps that your hardware doesn't support".
I'm curious why you've singled out me for this question.


No It's a logical question. A common perception is that to develop for a given architecture, then you need access to it. In some respects that's reasonable, and in others not. FWIW my first operational Cuda Fermi builds existed well before I had such hardware. Naturally without access to the hardware they were imperfect. So to me it just speaks to the argument that all avenues need to be explored. So to all sides my response is 'Suck it up buttercup', then strap yourselves in and prepare to feel the cheese,
158) 留言板 : Number crunching : Mac OS Sierra (消息 1844900)
发表于:28 Jan 2017 作者: Profile jason_gee
Post:


That Core i7 has no AVX2 so result is as expected.

I asked before, so I'll ask again,

TBar why are you, "playing around with apps that your hardware doesn't support?".

I know that I may seem to be an idiot times, but looks can be deceiving. ;-)

I admire the direction that you took after all our debates about the lack of AP's for you and I admire your current work with MB's with your selective OS's, but I'm puzzled by you doing this.

Cheers.


I would step in to defend the pokings, on the basis that what's being seen, with respect to changes happening, hasn't been seen in my time here since circa 2007. With the operating systems, compilers, tools, and hardware all changing at a faster rate than ever before, there is a massive number of unresolved questions/holes on what the next generation of applications will look like.

While I am definitely taking a back seat and watching a lot for the time being, there are valuable insights to be gleaned from what appears to be abject chaos. In that sense i'd argue that any number of good, bad and ugly approaches can pay off in the long run. i.e. it saves me work ;)
159) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1844454)
发表于:26 Jan 2017 作者: Profile jason_gee
Post:
A 5min +-30 seconds might help with the Scheduler and feeder loads, but as the number of active hosts increases, wouldn't the sheer number of hosts result in an (effectively) random load due to each system's randomness with the initial Scheduler request after BOINC starting?


Most likely the backoff needs to be proportional to the rate of requests, since the feed rate is likely more or less constant.
160) 留言板 : Number crunching : Panic Mode On (104) Server Problems? (消息 1844453)
发表于:26 Jan 2017 作者: Profile jason_gee
Post:
Yes 'unlikely'. That may possibly account for your ability to change settings, last for 12 hours, then fall back into a hole. I'll be very interested to see if you can break out of that rut without code change on client or server. Being Australia day, I'd like to point out that falling into such holes is pretty much the Australian way. Usually the result of doing so is fairly disruptive.


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