Gambit-list Juin 2009

gambit-list@iro.umontreal.ca

29 participants
47 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

2 2

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/

5 7

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

4 10

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

5 7

Compiling Gambit on Solaris 10
by Marc Feeley 30 Jui '09

30 Jui '09

Some people have reported that Gambit does not compile "out of the box" on Solaris 10 with gcc. The error message output by gcc when compiling Gambit is the following: In file included from /usr/include/sys/wait.h:24, from os.h:998, from _std.c:2273: /usr/include/sys/siginfo.h:259: error: parse error before "ctid_t" /usr/include/sys/siginfo.h:292: error: parse error before '}' token /usr/include/sys/siginfo.h:294: error: parse error before '}' token /usr/include/sys/siginfo.h:390: error: parse error before "ctid_t" ... It appears that the problem is caused by an improperly installed gcc (compiled on Solaris 9 and incompatible with the new header files in Solaris 10). The problem with gcc is discussed here: http://forums.sun.com/thread.jspa?threadID=5077618 A permanent solution is to recompile and reinstall gcc on Solaris 10 (as explained in the link above). A temporary solution is to use the following configure command: % ./configure CC="gcc -Dctid_t=id_t -Dzoneid_t=id_t" What this does is to define the ctid_t and zoneid_t types used by the Solaris 10 sys/wait.h file (these types did not exist in Solaris 9). There is another problem with the Gambit makefiles on Solaris (the use of a GNU extension to the sed utility). The fix has been pushed to Gambit's git repository. Marc

1 0

Questions about reading from a port and u8vector
by Lam Luu 29 Jui '09

29 Jui '09

Hello everyone, I am working on ICFP programming contest. There is something I am really confused about. Supposed that I have an input port, and I want to read the next 8 bytes as an IEEE 754 double value or a 32-bit unsigned integer, is there anyway to do this in Gambit? I mean, they are not string with digit '0' - '9', but actual representation of the number. Secondly, is there anyway to pass an u8vector to a C-lambda, as a char* or whatever? The C Interface section of the manual only provides information about character string, but not u8vector. Is it possible to pass u8vector as char*? Thank you very much, Lam Luu

3 3

reading file into string / length of file
by lowly coder 28 Jui '09

28 Jui '09

I want to read a file into a string. After I open it up, is there a way to get the length of the file? (or even before I open it up?) I see that we have read-substring and read-u8vector Currently, the best solution appears to be ... do a read-u8vector on it, get it's string length, then re-open the file and do a read-substring on it ... surely there's something more elegant. :-) Thanks!

2 2

overload pp for define-types
by lowly coder 28 Jui '09

28 Jui '09

Is there a way to overload pp for define-types? (maybe some undocumented arg in (define-type ...) ?) I would like to change how they're printed. Also, can I override existing ones, like f32vector? When I have something that's 1000 f32's, I'd prefer an output of <#f32vector ...> rather than all 1000 elems. Thanks! (If not, I'll just define a separate command like pp2 and use that instead, but overloading pp somehow seems more elegant).

2 1

heapoverflows
by lowly coder 28 Jui '09

28 Jui '09

I understand the when I get a heapoverflow, gambit can't pop me into a REPL (since that'll take more heap). However, can I get a dying process to print out a backtrace for me? (Increasing the maximum heap size won't solve this problem -- the problem is that I have some run away code that is consuming up all the memory, and if I increase the max heap size, all that happens is that it just makes it longer to heap overflow). [I debugged the last one manually by trying pieces of code here & there; but if I could get a backtrace, it'd just be so much faster] Thanks!

2 1

call on gc
by lowly coder 28 Jui '09

28 Jui '09

Is it possible to have an object X so that some function gets called when X is gc-ed? Suppose I have something like (define-type foo ...) (define bar (foo-create ...)) and inside of bar, there's a C-land resource that I want to have freed up when bar is GC-ed; Is there a way to have some function like (foo-gc) s.t. when bar is GC-ed, (foo-gc bar) is called? Thanks!

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Gambit-list Juin 2009