>>>>> "Michael" == Michael K Edwards <[EMAIL PROTECTED]> writes:
Michael> This is going to sound stupid, but have you tried it with Michael> either glibc 2.3.4 or Ubuntu's modified glibc? ... No, I haven't. I think I'll wait until it hits sid. Michael> Just to check: you are using the same compilation and linking Michael> scheme for both builds you are benchmarking, right? -fPIC and Michael> dynamic library thunks can add more than a little overhead to a Michael> slab-ish, usually-available-from-free-list malloc(). Yes, I'm using the same compilation scheme. I'm only changing the configure flags for libgc, and toggling linking with libpthread.a. Michael> Oh, and are there things in the header files that change from Michael> macros / inline functions to real function calls when you Michael> switch on threading? Not that I know of. Any such changes would be in the Boehm gc source; Asymptote doesn't care about whether or not the garbage collector is multithreaded. (Asymptote itself isn't multithreaded.) Michael> Note also the tuning issues discussed in Michael> http://www.hpl.hp.com/personal/Hans_Boehm/gc/scale.html , which Michael> includes benchmarks done on a now ancient kernel (2.2.12). If Michael> you are using -DPARALLEL_MARK on an SMP (or hyperthreaded) Michael> machine, and the scheduler gets the processor affinity wrong Michael> for the dedicated marking threads, I could see that having Michael> unfortunate performance consequences. If you have compiled Michael> with -DTHREAD_LOCAL_ALLOC but are not using the API in Michael> gc_local_alloc.h, you will be hurting. The configure flags for compiling libgc are: --disable-threads --disable-shared --enable-cplusplus (obviously with --disable-threads toggled for the different tests). I'm also running on a single-processor machine. Michael> In general, I think that the tool you need for this purpose is Michael> oprofile. You want to see where threads are sleeping (if at Michael> all), how much time is spent fiddling with spinlocks, etc. I'm Michael> a novice with oprofile but I'll be needing to learn about it Michael> Real Soon Now. Ryan, have you had occasion to throw this or Michael> other profiling tools at libgc? I'll take a look at oprofile, but I bet it'll take we a while to figure it out. -- Hubert Chan <[EMAIL PROTECTED]> - http://www.uhoreg.ca/ PGP/GnuPG key: 1024D/124B61FA Fingerprint: 96C5 012F 5F74 A5F7 1FF7 5291 AF29 C719 124B 61FA Key available at wwwkeys.pgp.net. Encrypted e-mail preferred. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
