Idle Loop Optimized

seebs writes "Every so often someone makes a joke about optimizing the idle loop, but this article actually does it. " It's about time too- that process has been eating up clock cycles for to long.

My idle loop is already optimized

[Anonymous Coward]

I run Gentoo.

Re:My idle loop is already optimized

[Profane MuthaFucka]

That's funnier than the story.

Re:My idle loop is already optimized

[NotoriousQ]

But is it unrolled?

Eating them up

[Deltaspectre]

It's always eating them up, right when I need them too!!! The odd thing is it's always decreasing to fit my needs... where are all my spare cycles?

Re:Slashdot only posts Stuff That Matters!

[jacquesm]

you know what, I've had it. I'm taking a 30 day break from slashdot in 'return' for all the great stuff that has been posted today.

ciao guys, see you on May 1st.

Re:Slashdot only posts Stuff That Matters!

[northcat]

Er, this is actually a real article. But stick with the 30 day break, trust me.

Re:Slashdot only posts Stuff That Matters!

[kyelewis]

You'll find the "real article" is indeed an April Fools Joke. Made obvious not only by the lucidrousness of optimising an idle loop, but by the descriptions of the author and the April Fools Day links at the bottom of the article ;)

Re:Slashdot only posts Stuff That Matters!

[seebs]

It is indeed an April Fools joke.

It also shows some neat things about vectorizing non-trivial examples.

hah

[Xaggroth]

finally.. a real post

Welcome to First Post Day!

[sterno]

Say, I'm curious, are you guys scripting this to post a new article every 5 minutes, or did you find some cheap outsourced labor to pound them out in real time?

Re:Welcome to First Post Day!

[kjamez]

india. /*
i am not lame.
i am not lame. */

Re:Welcome to First Post Day!

[northcat]

This is NOT an April Fools joke. This is real. RTFA.

Re:Welcome to First Post Day!

[chefren]

WHY, WHY, WHY would any sane person spend time optimizing something that doesn't do anything at all? Really, think about it. And then think about the reference to "Top 100 April Fool's Day Hoaxes of All Time" at the bottom of the article.

Re:Welcome to First Post Day!

[Lars T.]

First of all: there is more optimization in that article than just that of the idle loop (even if the given reason speeding up the generation of that spinning "beach ball of death" is another joke).

But that "idle loop" actually does something, it increments a counter - and thus calculates a lot of numbers. The optimized, vectorized loop does the same (yes, it does calculate the exact same numbers), just faster. Another victory for AliVec.

Grammar!

[darth_MALL]

"Every so often someone makes a joke about optimizing the idle loop, but this article actually does it."

The article does what? Makes the joke, or optimizes the idle loop?

Re:Grammar!

[jay-be-em]

Not really a grammar error so much as a grammatical ambiguety.

Re:Grammar!

[dgatwood]

What does my grandmother have to do with this?

Ain't it obvious?

[nsaneinside]

Naw, the /. post is referring to itself. It does both.

BASIC

[FriedTurkey]

10 PRINT "I am awesome"
20 GOTO 10

Re:BASIC

[Codifex Maximus]

Syntax error line 10: Unknown token at end of line.
10 PRINT "I am Awesome ";

You are obviously a sickly C programmer! BASIC rox donchaknow?

Re:BASIC

[Codifex Maximus]

10 PRINT "I am awesome!":GOTO 10

We are trying to optimise remember?! Get with the program.
Sheesh.

World's Smallest Slashdot Effect Found

[Dynamoo]

After a huge run of articles, the world record for the lowest number of hits on a website due to the usually massive Slashdot was recorded.

The webmaster in question said "yeah, I noticed a couple of extra visitors, but my TRS80-based web server coped just fine.".

Going for the record?

[chill]

Show some restraint. It isn't necessary to publish EVERY LAST APRIL FOOLS JOKE found on the Internet. Give it a rest already!

-Charles

Re:Going for the record?

[MatthewNewberg]

Too late, I've already done it.
http://mnewberg.com/content/view/78/2/ [mnewberg.com]

Re:Going for the record?

[Tony Hoyle]

by chill (34294) Alter Relationship on Sat April 02, 12:29 AM

Especially as it isn't april fools day any more.

GIVE IT A REST PEOPLE!!!

Also

[The Spoony]

You can choose to run something like SETI@Home, or if you'd actually like to make a difference, Folding@Home [stanford.edu].

they must have a SlashStory Generator

[Fox_1]

Slashdot Story Generator [bbspot.com] only they one the editors have is better, because it actually links to real stories.

I can do even better....

[popo]

Today at work I was in a spectacularly smooth (and remarkably energy efficient) idle-loop.

Fortunately the loop was terminated automatically at 5pm.

Yeah, but....

[cmsavage]

...have they implemented multicore support for greater speed and accuracy?

Re:Yeah, but....

[SmurfButcher Bob]

Yeah, but the licensing fees will kill you.

And now for something completely different. . . .

[Anonymous Coward]

Isn't it awfully nice to have a penis?
Isn't it frightfully good to have a "dong"?
It's swell to have a "stiffy",
It's divine to own a "dick".
From the tinyest little "tadger",
To the world's biggest "prick".
So three cheers for your "Willy" or "John Thomas",
Hooray for your "one-eyed trouser snake".
Your "piece of pork",
Your "Wife's best friend",
Your "Percy" or your "cock".
You can wrap it up in ribbons,
You can slip it in your sock.
But don't take it out in public,
Or they will put you in the dock,
And you won't come

Where is my TPS report?

[neckdeepinspecialsau]

Um could you optimize the idle loop? Yeah... that would be great.

Re:Where is my TPS report?

[BorgCopyeditor]

Yeah, I've been meaning to talk to you about that. I'm gonna need you to go ahead and stop quoting that movie now, OK? Great.

code snipplet

[voot]

while(1) cout "/.\n"

Uses

[ch-chuck]

Great, this technology will allow me to do nothing even faster and with greater efficiency.

I hate it when I give a cpu an idle loop, and come back later to find it's not even running, lazy bastard. Seriously, after prototyping a new processor the first test it gets is something like
0000 jmp 0000, or after getting a VHDL z80 to run in ModelSIM the first thing I did was slowly stepping thru a similar loop to verify it was actually 'fetching and stepping' (manually putting the instruction in the bus since I d

Anyone else read the whole thing?

[CrackHappy]

This is a joke, but man if I didn't know programming I sure would have fallen for it. It's all so... reasonable.

Jesus - optimizing the idle loop - the way he ends up doing it just cracks me up.

It's not all a joke

[songbo]

True, the article is partly an april fool's joke. What would you get by optimizing the idle loop? More cycles of the idle loop running in your idle time! But the 2nd half of the article discusses Altivec instructions. And seriously, there's useful information to be found there if you're writing Altivec code.

Re:It's not all a joke- 4bsd history

[Anonymous Coward]

There was a similar one years ago about optimizing the idle loop of 4bsd Unix on the VAX. Turns out there was a real reason to make the change, a bug report was filed and the optimization was implemented. The "broken" idle loop did some computation and then checked to see if there was other work to do. If the computation got faster, then the latency in noticing that new work arrived got lower. Lower latency is usually a goot thing. Note that the techniques expoused in this article might even increase th

Brilliant!

[steveha]

I love this sort of thing. The basic idea is silly, but he manages to show some useful stuff and make some valid points while exploring it.

I remember in the 1980's there was a great article on how to add a GOSUB keyword to the FORTH language. The article evolved the code through four different versions, and each one showed something cool and useful about FORTH. Well, maybe not the last one:

: GOSUB ; IMMEDIATE

For those of you who don't grok FORTH, this defines a keyword called GOSUB that does nothing, and does it at compile time so it doesn't get compiled in either. (The article noted that GOSUB FOO is the same thing as just plain old FOO, since FORTH functions are always called as subroutines anyway.)

Around the same time, I saw an article on how to build your own 64KB memory: take a breadboard, and 65536 8-bit flip-flop chips, plus a 1:65536 multiplexer and a 65536:1 demultiplexer for address selection! The article helpfully calculated how many Watts of power it would take to drive all these chips (a LOT) but it didn't say where one might find a multiplexer or demultiplexer with over 65000 pins on it.

steveha

Re:Brilliant!

[AdamWeeden]

OT but couldn't you use a series of multiplexers/demultiplxers?

Re:Brilliant!

[steveha]

couldn't you use a series of multiplexers/demultiplxers?

Well, in real life you would have to.

Even a modern ball grid array [wikipedia.org] chip doesn't have tens of thousands of pins; a few hundred at most. Back in the 80's, with the dual inline packages [wikipedia.org] for chips, a few dozen pins at most was the limit.

So if you were insane enough to use a few thousand 8-bit flip-flop chips to build a memory, you would need to cascade a series of multiplexers and demultiplexers. I'm not really a hardware guy, but here's how I think

Another problem

[old_unicorn]

I'm also worried about the lack of a decent defragmenter for the unused portions of my hard disk....

About the optimisations

[gothmog666]

Sorry man, but the compiler shoulb de doing that.
Loop unrolling is the _basics_.

You should worry about better design and readability.

Auto-vectorization is a step for GCC 4.0, thought.

Hah!

[seebs]

http://www.theinquirer.net/?article=22318 [theinquirer.net]