About

Michael Zucchi

 B.E. (Comp. Sys. Eng.)

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Wednesday, 20 June 2018, 14:39

Ahh google, the `great' advertising company!

Oh nice one, they've decided to block all of Blender's videos on youtube because they don't want to turn on advertising.

Essentially blackmailing them into becoming part of their slurping adversiting empire where they get to make most of the money from peoples labour whilst paying a pittance. Despite not being a real user of it, as one of the original supporters who helped fund the freeing of Blender way back when with a few hundred dollars I'm pretty apalled they would be treated this way (although not surprised).

Fortunately the technology is coming together so that alternatives exist to a monolithic/expensive server such as PeerTube which uses WebTorrent, or InterPlanetary File System (IPFS), and others. blender.org is experimenting with a peertube instance at video.blender.org already.

Of course that only works so long as bittorrent isn't blocked, or WebRTC isn't blocked, or backbone operators start to throttle protocols competing with those that are part of their corporate conglomerate or have not been paid for. Or regulatory capture though some pro-establishment law effectively bans it (like the EU Copyright `Article 13' crap happening now).

Even if some backlash makes them change their mind it's just another example of the problem of corporate centralisation/ownership of culture.

Tagged free software, rants.
Saturday, 27 October 2012, 12:30

64 core Parallela & ARM A9 Zynq

Well it looks like the Parallella endeavour did get funded after-all (just minutes ago). They only really got organised in the last 3 days so I really thought it was too late but they managed to get the word out and excitement up enough to make it.

Well done.

As I said previously, the 16-core chip is a teaser and the 64-core is where the action is ... So I was pleased they offered a guaranteed 64-core version once it was clear that the $3M target was a bit optimistic. So even I, the cynical old c**t that I am, got caught up a bit in it myself and went for the 64 core chip plus the early 16 core one, cases and a t-shirt. A bit of an indulgence but I can afford it.

I'm sure most people don't really understand what they're getting into (that's pretty much the modus operandi of Kickstarter), but a Zynq board for $100 is still good value apparently even without the floating-point accelerator tacked on.

Although they just made it now, it's still open for a few hours, so get over there and have a poke if you're interested in a fully documented open embeddable low-power platform - i.e. ALL of the components will be documented and include ALL the free software to access it, including the accelerator. (well, this is what is promised, i'm not sure how far it stretches to the ARM/Zynq, but I presume that is already covered elsewhere).

This is in stark contrast to other 'open' boards such as:

As the basic board comes with a 'Zynq' processor, which is a dual-core A9 plus a FPGA on chip, it opens up more than just parallel processing to 'the masses' to include reconfigurable hardware too. I don't know much about these but I have it on good authority that they are very cool chips and i'm looking forward to investigating that aspect as well - if i ever get the time to (the lack of free tools there might impede too).

Given this open nature i've been a bit bummed by some of the hostile reception it's received in some of the 'open hardware/software' forums and mailing lists. Come on fellas, the world is big enough for more players - no need to get so defensive. And given how much of a whinge they've all had about vendor documentation, GPL violations, tainting buggy binary driver blobs, and everything else the cool reception is more than a little baffling. If nothing else some competition has to help making progress with other vendors who have all closed ranks.

Scalar vs SIMD, not all FLOPS are equal

I think some just don't see what the big deal is - it's just a chip not a solution, so and so have a chip that does x flops too, blah has something coming that will blow it all away, or those total flops just aren't that much ...

The problem with marketing numbers is that they're just marketing numbers. Peak FLOPS are impossible to achieve with any cpu and any algorithm - but the main avenue for increasing the FLOP count for the last 20 years - SIMD - only makes this much harder to achieve.

GPU's only make this worse. They throw so much hardware at it you still get very good results - but they aren't efficient at many tasks, and difficult enough to programme for the ones they are.

I'm sure you'd have to be living under a rock to miss the fact that when the Playstation 3 came out, a lot of developers made a lot of noise about how difficult it was to programme for. If you put in the time - and you really had to resort to assembly language - you could get phenomenal through-put through the SPUs, but if you didn't, all you had were 6 fairly gutless cores which were on top of that - a bit tricky to use. And it used a lot of power to get there.

Although the Eiphany shares some of the trickiness of use that the SPU's do (including the cache-less local memory, although it's easier to access off-core memory), simply because it is scalar a higher flop utilisation rate should be achievable for normal code. Without having to resort to assembly language or even worse - intrinsics. Not to mention the power differential: 90 odd gflops for the 64-core version ... in 5w system power.

A floating point MUL only has a latency of 4 cyles too - rather than the 7 on the CELL or 6 (iirc) for NEON, which makes the compiler or assembly language writer's job of scheduling that bit easier as well. Although assembly is an absolute must for NEON, the instruction set it so simple and there are so many registers i'd be surprised if it was needed in practice for the epiphany core.

Another point about competitors - ziilabs thing looks awesome! An embedded chip with a programmable multi-core co-processor! Yay! Oh, I can't actually get a machine with one in it? Oh. It only runs Android - a cut down, appliance version of Linux? Boo. Even if you could get one the grid-cpu is proprietary and secret and only we're allowed to use it, and you must go through the framework we provide? Blah, who cares.

Nothing's perfect

Engineering is not mathematics or science. Mathematics is absolute. Science is knowing to within a known degree of knowing. Engineering is a constant compromise. The real world has a habit of getting in the way. Cost, time, knowledge, physics, they all conspire to prevent the attainment of mathematical perfection.

The human curse that we all bear is that if we ever actually got what we truly wished for, we'd just think of something else we wanted.

PS This list is just my take on a fairly quick reading of the architecture documents and instruction set, it may contain wildly inaccurate misreadings and other mistakes.

Software
Well they're opening everything up for a reason, the 4 (or 5?) man team just doesn't have the resources to fill out everything. It's cheap enough that there should be no real barriers to entry to poking around, and the more that poke the more that gets done for free. This will be an interesting test to see how a loose group fares against multinational corporations and commercial standards bodies in coming up with usable solutions.

So it might be a while before X is accelerated, if ever.

The thing that most gives me the willies is that the sdk is based on eclipse, but it uses gcc as the backend anyway.

Memory
The 16 core version only has 32K SDRAM per core and 512K total per chip. And that includes both instruction and data. This per-core amount is the same as the cache on most ARM chips and will be a bit tricky to deal with. However this isn't a hard limit, just the limit on what is cheapest to access. OpenCL kernels are usually a lot smaller than this though, and so you can certainly get real work done with it. Not being confined to the OpenCL programming model would also enable efficient implementation of streaming (which is another way to save memory use).

The low latency instructions means loops wont have to be unrolled so much to hide them, so it should be able to achieve a higher code density anyway (not to mention the 16-bit versions of every instruction).

No cache
Only local memory. Programmers do hate this ... but the benefits you get from not having one are worth it here. A lot less power and silicon on the hardware side, and even though it might be a bit tricker to write efficient code, you're not getting hit with weird an unexpected results either because some data size hit cache tag aliasing. It goes a bit further than that too - no need for hardware memory barriers either, a write or read is a write or read to or from the target memory, not some half-way house. No cache snooping required.

I thought this (LDS) was one of the coolest features of SPUs, and it's a must-have in OpenCL too.

Latency
As one goes further from your local cell, the latency of memory access goes up quite quickly because as far as I can tell, each lane only goes one over and it requires multiple hops. But application-accessible DMA can be used to hide this and since you'll use it with the small local memory size anyway, it kind of comes for free.

Memory protection, virtual memory
None at all whatsoever on the accelerator. This is another bullet point as to how it achieves such a high flops/watt ratio.

Hardware threads
None. Rather than hide latency using multiple threads, one uses DMA.

Synchronisation primitives
None none that I noticed beyond a test and set instruction. This is a bit of a bummer actually as this kind of stuff can be very cool and very fast - but unfortunately it is also a gigantic patent minefield so i'm not surprised none is included. I'm talking about mailbox queues and mark/release type instructions for non-blocking primitives.

Since a core can only talk to its neighbours, this is probably not so useful or important anyway now I think about it.

Tagged beagle, free software, opencl, philosophy, rants.
Friday, 24 August 2012, 10:24

The second golden age of personal computing.

With interest and some excitement (despite it being Nokia Nikon and having some negative experiences with them), I just read that Nokia have announce an Android powered camera. Of course, it's all ostensibly about feacebook and twatter, but one can easily see a world of more practical use to an appliance on which you can install customised software. Let's just hope that a DSLR isn't too far behind - although camera vendors may fear having the shift-ful proprietary software they took years to develop improved upon and obsoleted by someone else.

It is rather ironic that whilst desktop computer operating systems are locking down, dumb-stupifying and generally turning general purpose machines into appliances, appliance makers are opening up, complicating, and turning appliances into general purpose computers.

And at the heart of it, it's all thanks to Free Software. 'Onya RMS.

And it's no doubt also thanks to the purest form of capitalist economics. It is simply cheaper to use a free operating system than it is to write your own or purchase a per-appliance non-free one.

First Golden Age

I consider the first Golden Age of personal computers to the time before Microsoft Windows and their illegally attained `wintel' monopoly.

So these developments are clearly also a result of breaking the back of the wintel monopoly and the USA based global technology plutocracy.

Who would have thought that a bit of competition would benefit we the little people?

Second Golden Age

So I feel we're entering another 'golden age' of computing: where anybody with the skills can improve upon or replace the usually shitty software that comes with any device - as every device is now powered by substantial software components this equates to a lot of computers. With any luck I will never have to purchase a locked-down throw-away appliance ever again ...

However, I fear as with all golden ages, this one will also not last and eventually they will try to pull a M$ on us ...

Ultimately however economics will force their hand, and any such tactics will prove too costly to maintain.

But what cost to society will such experiments first extract?

Update: Thanks Sankar, yes Nikon, too much Tomi on my brain that morning. And of course, Samsung have followed up with announcing their Android camera ... yum.

Tagged android, free software, gnu, politics.
Thursday, 01 March 2012, 13:21

It's scary joining a free software project?

I started writing a comment on this this post about contributing to free software: and it got so long I thought I'd move it here.

Overall I agree: it is quite scary, but the comment I was writing follows, somewhat expanded.


For the types of people for whom meeting people is difficult, software projects cannot be any different because the same notions apply: you don't really know how someone will react to you and whether you will be accepted or respected. I've been writing free software for about 15 years, and before that I gave away 'freeware' as well, and i'm probably more anxious about contributing to a new project than i've ever been ...

It is also unfortunate you use the term 'open source', because clearly merely having access to the source code makes no representation on whether a project is even interested in contributions. There are many reasons people write software and publish it freely, and for many projects, success or popularity is simply not a concern: the developers don't really care what anyone thinks because they have something they use themselves and the sharing is already an end in itself.

However ignoring the specific terminology used, trying to brush a wide audience with their sole unique characteristic is generally a pointless exercise. e.g. that all Greens voters are smelly hippy vegetarians, conservatives are all gun tot'n 4WD drivers, etc. People with only a few things in common are still very different from each other.

And just because the source is available and has a project page and a mailing list, it doesn't mean the project is interested in contributions from the general public. But clearly Layfield's experience is pretty poor - if a project purports to desire contributors and has a work wanted list, then at the bare minimum civility and politeness should be present. If such a project intends to survive by using external contributions, then it wont live too long.

Some of my experiences:

a) 'my first elisp' code, which turned into a handy script to add java-doc like comments to C functions. I submitted this to emacs, but RMS wanted it integrated into CC mode and a bunch of other stuff which was well beyond the time I wanted to spend on it or the features I needed (and I wasn't particularly interested in the kudos of contributing to a high-profile project). So I just added it to the project repository and my .emacs and left it at that.

(needless to say, I never wrote any elisp subsequently, but that's because I just wasn't interested in lisp as a language and that was the sum-total of the lisp I ever wrote).

b) AROS - these guys were very easy, commit access was easy to get, and then it was pretty much commit what you liked - obviously avoiding stepping on any toes. Even for a project with a lot of politics, there were plenty of small holes to fill.

c) I submitted a patch to mplayer, which was accepted without too much fuss. Just a bit of formatting changes iirc. In hindsight this was smoother than i'd have thought: certainly at the time they gave an abrasive impression of themselves on their web-site.

d) I think the first free software i contributed to was a patch to amanda circa 1995 - amanda is a distributed backup system. It was a horrible patch in hindsight but they accepted it easily. Of course this was back in the day when the internet was only accessible to academics, students, engineers, and sysops and overall was a much nicer place (yes, despite the flame-wars).

e) Working on Evolution. This was a commercial product with a (reasonably) defined direction and design. It was also complex enough and with enough of a user-base that any changes needed a lot of checking to make sure they were going to work technically and be up to scratch in terms of quality. Although the whole team spent quite a bit of effort trying to increase the community involvement: In the end I didn't really like being offered all but the most trivial of patches because it was always much faster just to write the code myself. Or I felt like a real heel telling some young lad that we couldn't use his patch because it didn't fit with the PM driven agenda. The one time we did accept a sizeable patch (and I was on holidays so was overridden), I spent weeks replacing a poor implementation which caused a lot of problems with a decent one. Nobody ever became a long-term contributor so we were left to learn and maintain any patches they gave us as well. I thought the 'bounty' system was an unmitigated disaster and would never consider such an approach again. People who are desperate for the paltry money on offer are probably not the cream to start with, and it is also very unlikely to lead to long term unpaid commitment.

Developers ...

Developer scalability was a huge issue in evolution: with thousands of reported bugs/feature requests and 2-3 coders there's just nowhere to even start making a dent. People wanted stuff we could never deliver (either too costly, unfit for the application, etc), and some people were nasty and insistent arseholes who wouldn't take no for an answer, or wouldn't take any time to try a patch or other work-around suggestions (which obviously took non-trivial effort to suggest). Crash reports were rarely followed up, and without being able to re-create them were basically useless. Not to mention distributions (esp debian) re-packaging the code in ways we only had to guess, and maintaining their own separate patch-sets. Placing bugs into 'wishlist' limbo was just as bad as saying 'wontfix', since they were never going to happen.

This latter point about scalability can't be ignored even for projects which do actively seek contributors. Every contributor comes along with a clean slate and thinks they're the first to be in their position. Yet for developers they might be one of hundreds, and even after giving out the same information only 10 times one gets pretty sick of it. This is actually one reason I find it more difficult to contribute to projects now: I don't want to piss someone off because I couldn't find their FAQ or didn't search the email archives enough, or they're still anal about 'top posting' (I really can't believe anyone still gives a rats-arse about that anymore ...).

Submitters ...

The 'problem' isn't just with the developers either: for example, what is the motivation behind the people submitting the patch? Why should a developer be particularly interested in a patch from someone who is just after the experience of submitting a patch? Or hoping for the fame of having a bit of their code included in a popular application?

I would certainly be much more interested in a patch from an active user who has found a deficiency in their day-to-day active use of the project versus someone who is just looking for something to do or something to add to their CV.

And if you're not a direct or close peer to the developer: the relationship is in quite a different space and now the developer has become a mentor. It takes far more effort and resources to be a mentor and in the vast majority of cases that effort is never returned to the project. The goal of most projects is to provide a solution to a problem, not to train people how to code or interact with a public project. It's quite arrogant and rude to assume that just because it's code and mailing list is available to the public that it gives the public a free reign on developer time ...

Me ...

Now, i'm definitely not interested in authoring applications for the general public. I get paid to work on a research project with a single individual as the sole customer I deal with. And for my free software projects the only ones of worth are only useful for other developers. And even then most of those are just stuff i'm playing with for my own entertainment; it is therefore costing me nothing to share it with the world and i'm more interested in helping people learn than solving their problems (that's not to say I don't get a buzz out of knowing my stuff is used - I check the stats all the time - but it isn't the motivation at all).

I don't think it will happen any time soon (not the least reason being that I'm miles away from building anything useful to the average user): but having a project of mine picked up by a distribution would be quite unappealing.

As for patches, I still submit the odd small patch here and there. But what turns me off is:

Anal retentiveness about specific code style, mailing list etiquette and so on.
I used to do this way way too much in evolution: If the patch was basically ok I should've just taken it and fixed it up to match my preferences and fixed minor errors. Once one has submitter access things are different, but for a random patch it's just not worth the to-fro and agro. Previous to ximian I'd had a pretty unpleasant experience working with an Indian sub-contractor (TATA Infotech) and we were being anal about their (really bad) code because we were paying a lot for it for no reason - so I was a bit thingy with code reviews.

Worrying about 'top posting'? How 90s, get-the-fuck over it.

Using git (or some obscure cms)
I just hate git to start with. And being asked to create a public fork of a project for a one-off small patch is low on my list of `things to do before i die'.

The first patch I ever created I used 'diff -ruN' to create, and that's still a reliable way to do it without having to learn obscure commands for half a dozen popular systems.

Too many pre-requisites.
e.g. joining a mailing list and a bug tracker in which you must create a bug and attach the patch, copyright assignments, and so on. It's ok for a couple of projects or if you become an active long-term participant, but it quickly gets far too unwieldy if you're just submitting a rare patch to some product you use occasionally. Another thing we (totally!) fucked up in evolution.

Obviously for a team project a mailing list (or forum) is pretty much essential, and legalities might require a copyright assignment or other agreement, but the bug systems tend to give me the willies.

Build complexity.
Some projects are just too complex to build or require too many pre-requisites: rubbish like ant, cmake, and all the other weird arsed build systems (jam, bitbake, custom python, rake ...) become insurmountable barriers that stop you even getting started.

I was quite astonished the other day that I even got a cmake based project to compile at all. If it wasn't for netbeans I wouldn't be using ant, and even then it sometimes fucks it up.

Python.
Which reminds me ... it's just a personal thing but I detest python in any form. tcl isn't far behind.
Arrogance.
Using a project leader's celebrity or the project's popularity to make one feel like it is an absolute privilege to be doing some of their work for free. I don't really encounter this because I'm just not attracted to such projects, but there needs to be some sort of recognition that work is being done for free (assuming it's at an adequate level for the complexity of the patch).

Concluding ...

To respond to the final question of what can be done to improve first impressions, I think i'd just say 'not much'.

Unless your specific goal is to maximise user contributions and popularity amongst potential contributors you're probably not too concerned about what they think. And if you are, you're probably already doing all you need to do.

And importantly beyond some fairly basic civility, there should be absolutely no obligation on you, as a free software developer, to provide any sort of expected level of support or accept patches in any form from anyone whatsoever.

If one wishes to be popular and extra-friendly then all the better for you and your users, but it is certainly no pre-requisite to calling your software free (or the related but somewhat meaningless term 'open source').

Tagged free software, politics.
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