Gambit-list Mai 2009

gambit-list@iro.umontreal.ca

22 participants
44 discussions

Edge triggered I/O with libevent
by Adam Langley 04 Avr '13

04 Avr '13

Gambit uses the select call on POSIX systems to multiplex IO operations. This is fine for small numbers of file descriptors, but falls apart quickly with large numbers[1]. libevent[2] is a wrapper library around a number of modern IO multiplexing systems (epoll on Linux, kqueue on the BSDs as well as poll and select). Attached is a patch which converts Gambit to using edge triggered I/O with epoll and libevent. This also requires a patch (attached) of libevent since the standard distribution doesn't include edge triggering support and the upstream appears to be on holiday. (epoll is required because I don't have a BSD box on which to develop edge triggering support for kqueue) This patch (for Gambit) preprocesses away to nothing unless --enable-libevent is passed to the configure script. (Note that, since this patches the configure.ac script, you'll need to run autoconf to regenerate). I hope I've not broken anything, but at this stage I've only tested that the console and tcp ports work. This patch (in the future) should also allow people, who write programs which use socket calls directly, to integrate into the main event loop at some point. Testing is more than welcome and, if you find a form of IO which is broken, please email me. [1] http://monkey.org/~provos/libevent/libevent-benchmark2.jpg [2] http://monkey.org/~provos/libevent/ -- Adam Langley agl(a)imperialviolet.org http://www.imperialviolet.org (+44) (0)7906 332512 PGP: 9113 256A CC0F 71A6 4C84 5087 CDA5 52DF 2CB6 3D60

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Interactive 3D graphics with Gambit-C
by Alex Sandro Queiroz e Silva 06 Jan '10

06 Jan '10

Hallo, I am thinking about doing some basic 3D graphics with Gambit-C. Although I am sure code generated by Gambit-C is fast enough[1], I am a bit worried about the garbage collector. What's the type of garbage collector used by Gambit? If it kicks in during interactive rendering, should I expect annoying pauses? [1] - http://www.ventonegro.org/2008/09/the-need-for-speed/ -alex http://www.ventonegro.org/

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Re: [gambit-list] Speed improvement of lib/digest.scm
by Marc Feeley 18 Nov '09

18 Nov '09

On 19-Feb-09, at 4:49 PM, Mikael More wrote: > Cool! > > Useful! > > What is the approx speed on your machine btw? > On my 2GHz Mac Book Pro: For MD5: 0.06 seconds per MB. For SHA-1: 0.13 seconds per MB. That's still about 3 times slower than the "md5" utility on my machine, but still not too bad for bit-bashing code entirely written in Scheme. Marc

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scheme on llvm
by lowly coder 31 Jul '09

31 Jul '09

this is kinda off topic, -- but people here seem really smart, so I'll risk the occasional flames for good criticism + insight i think the llvm/jvm projects are really cool, since so much work is put into jitting; and for one reason or another, I like llvm more than jvm i'm curious about the possiblity of a high performance scheme (and perhaps gambit in particular) running on llvm; where the 'initial implementation' may not be all that fast ... but letting llvm jit it away how does this sound? feasible for a scheme (but not gambit)? down the pipes planned for gambit? or totally stupid/crazy? the 'main' advantage of this approach is that I _assume_ that the llvm guys are pretty good at hacking up interpreters / jit's ... so why not benefit from their constant progress :-D

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multithreaded debugging fun
by lowly coder 20 Jui '09

20 Jui '09

Please see typescript (sorry, copy/paste not working in X right now) i have test.scm, which forks off a thread (<thread #2>) which forever does: (pp 'yay); so I can see it print (+ "asdf" 1) ; just to generate an error I'm running gsc with -:dar, so i want debugging support, for all threads, and get thrown into a REPL when an error occurs. Here are my questions: 1) in my primordial thread, why do I have to execute some command (like "(void)") before I get thrown into the REPL in thread2? if everything is running concurrently, why does the error in thread2 not pop up immediately and get me thrown into a REPL? 2) in thread 2, after hitting ,(c 0) ... why don' i immediately get an "yay"? (if it's continuing from that error, it should jump back to the (pp 'yay)) 3) after printing said 'yay', why do I have to hit (void) in the thread #1 before getting the error repl in thread 2? why doesn't the error immediately happen 4) it seems like i'm ping-ponging between the two threads on the REPL. Is there anyway I can control this myself? (i.e. some command to jump me to thread1, some to jump me to thread2?) Thanks!

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I/O puzzle...
by Marc Feeley 09 Jui '09

09 Jui '09

Puzzle... what's the bug in the following code? See end of message for answer. (define http-server-start! (lambda (hs stop?) (let ((server-port (open-tcp-server (list port-number: (server-port-number hs) backlog: 128 reuse-address: #t server-address: '#u8(127 0 0 1) ; on localhost interface only char-encoding: 'ISO-8859-1)))) (input-port-timeout-set! server-port 3) (accept-connections hs server-port stop?)))) (define accept-connections (lambda (hs server-port stop?) (let loop () (let ((connection (read server-port))) (if (eof-object? connection) (if (stop?) (close-input-port server-port) (loop)) (begin (if (server-threaded? hs) (let ((dummy-port (open-dummy))) (parameterize ((current-input-port dummy-port) (current-output-port dummy-port)) (thread-start! (make-thread (lambda () (serve-connection hs connection)))))) (serve-connection hs connection)) (loop))))))) . . . . . . . . Answer: the (input-port-timeout-set! server-port 3) is at the wrong place. It sets a timeout ***3 seconds in the future***. So after 3 seconds have passed all calls to read in accept-connections will not block (and lead to a tight, CPU intensive loop). The correct approach is to put the call to (input-port-timeout-set! server-port 3) just before the call to read. Puzzle #2: why did Gambit chose to define timeouts that are not relative to the moment that an I/O function is called? Marc

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Termite + Black Hole
by Jamie Briggs 06 Jui '09

06 Jui '09

On the Black Hole page of the Gambit wiki, in the "additional Libraries" section there is the line: Termite: A version suited for usage in Black Hole is found at X. Are BH and Termite currently incompatible? And if so, how? I was just going to try using them together but then realized I would probably notice gross problems but might be not catch subtle ones. - Jamie

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profiling code being interpreted by gsi
by lowly coder 31 Mai '09

31 Mai '09

Hi! I have a largeish gambit application. It's interpreted under gsi, and is taking up around 25% of my dual core laptop. I would like to profile to see what functions are taking up all the time. How can I do this? (Searching for profiling in the gambit documentation brings up stuff focused on how to profile scheme code that has been compiled to C, but not on profiling of interpreted code.) Thanks!

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[Fwd: Measuring FSF gcc from 4.1.2 to today on various benchmarks.]
by Bradley Lucier 29 Mai '09

29 Mai '09

I've run some statistics with various versions of gcc and sent the following message to the gcc mail list, which is archived at http://gcc.gnu.org/ml/gcc/ Perhaps some of you may be interested. Brad -------- Forwarded Message -------- > From: Bradley Lucier <lucier(a)math.purdue.edu> > To: gcc(a)gcc.gnu.org > Cc: Bradley Lucier <lucier(a)math.purdue.edu> > Subject: Measuring FSF gcc from 4.1.2 to today on various benchmarks. > Date: Fri, 29 May 2009 15:58:00 -0400 > > I've put at > > http://www.math.purdue.edu/~lucier/bugzilla/9/ > > some compile-time and run-time statistics related to PR 39157 and PR > 33928 and compile times and run times for the programs in the Gambit > Scheme benchmark suite. The statistics are for 4.1.2 release, 4.2.4 > release, 4.3.3 release, 4.4.1 20090522, 4.5.0 20090521 (revision > 147758), and 4.5.0 20090521 (revision 147758) with > -fno-forward-propagate; they use (mainly) the set of options > > -O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math -fno-strict-aliasing -fwrapv -fomit-frame-pointer -fPIC -fno-common -mieee-fp > > on a Core 2 quad processor (running basically nothing else at the time). > > I would conclude from the statistics that, right now, the cost of > including -fforward-propagate in -O1 overrides any performance benefit > that may result. > > Brad >

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Gambit positively spotted on slashdot
by Adrien Piérard 29 Mai '09

29 Mai '09

Recently, my friend John wrote a webserver in CL that made its way to slashdot. That's a good thing for FP and lisp based languages. The article can be seen here: http://tech.slashdot.org/article.pl?sid=09/05/25/1553220 Moreover, in the comments, someone inserted Gambit in the discussion, using infix notation: http://tech.slashdot.org/comments.pl?sid=1244601&cid=28087817 I believe this too is a very good intervention in favor of Scheme and particularly Gambit. P! -- Français, English, 日本語, 한국어

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Gambit-list Mai 2009