Re: Basic question about threads and SMP
Being multi-threaded has almost nothing to do with being multi-processor. Multi-threading means that your application has multiple threads of execution that are able to run simultaneously. The multi-processing capability of your box means that 2 threads of execution, be it a process or a thread within a process, are executed _literally_ at the same time, and not in simulated concurrency like it happens on a UP box. Whether or not any application should be compiled with libc_r depends solely on the application itself. And, as you suggest, that is decided at build time. If applications support multi-threading they normally come with a Makefile using libc_r. Now, whether you want to multi-thread Apache is totally different issue ... Nick On Wed, 1 Dec 1999, Doug Barton wrote: You know, a stray thought just occured to me, which hopefully won't sound to silly to people who know about this stuff. :) If I have an SMP box (using -Current specifically) do I want to be compiling things with -lc_r? I'm thinking specifically of mission critical things like apache, but in general will other ports and such take advantage of libc_r if they are compiled with it, or would a program that _can_ take advantage of it already have that built in, say into autoconf or some such? What about other parts of the base system? I'm assuming that the kernel is covered by virtue of the fact that I've enabled the SMP options, yes? I'm trying to learn more about SMP, threads, and such like in general. The recent conversations about those topics on the lists have been very educational. I'm still wading through them, but I appreciate being able to sit on the sidelines and glean bits here and there. Thanks, Doug -- "Welcome to the desert of the real." - Laurence Fishburne as Morpheus, "The Matrix" To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message -- [EMAIL PROTECTED] [EMAIL PROTECTED] USB project http://www.etla.net/~n_hibma/ To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: Basic question about threads and SMP
%Nick Hibma wrote: % % Being multi-threaded has almost nothing to do with being % multi-processor. Multi-threading means that your application has % multiple threads of execution that are able to run simultaneously. % % The multi-processing capability of your box means that 2 threads of % execution, be it a process or a thread within a process, are executed % _literally_ at the same time, and not in simulated concurrency like it % happens on a UP box. % %Note that this happens ONLY if both threads of execution are processor %mobile. If your system supports user-space threads as part of a %process and the process can't be split across CPUs, you might as well %have a UP system. (Except everything else can run on the other %processor, so SMP is still a small win.) % %This is the situation with threads and SMP in -current. % The LinuxThreads port is currently busted for SMP but when it is fixed it will indeed use multiple processors: last pid: 395; load averages: 0.50, 0.11, 0.04 up 0+00:13:00 20:00:40 37 processes: 6 running, 31 sleeping CPU states: 65.8% user, 0.0% nice, 0.0% system, 0.0% interrupt, 34.2% idle Mem: 8780K Active, 9116K Inact, 19M Wired, 68K Cache, 7000K Buf, 466M Free Swap: 1024M Total, 1024M Free PID USERNAME PRI NICE SIZERES STATE C TIME WCPUCPU COMMAND 393 rcarter 31 0 876K 152K CPU1 1 0:01 17.16% 2.39% ex3 394 rcarter 29 0 876K 152K RUN0 0:00 15.76% 2.20% ex3 391 rcarter 30 0 876K 152K RUN1 0:01 14.71% 2.05% ex3 395 rcarter 30 0 876K 152K RUN0 0:01 14.01% 1.95% ex3 392 rcarter 30 0 876K 152K RUN0 0:00 13.66% 1.90% ex3 Russell %-- %"Where am I, and what am I doing in this handbasket?" % %Wes Peters Softweyr LLC [EMAIL PROTECTED] http://softweyr.com/ % % %To Unsubscribe: send mail to [EMAIL PROTECTED] %with "unsubscribe freebsd-hackers" in the body of the message % To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Basic question about threads and SMP
You know, a stray thought just occured to me, which hopefully won't sound to silly to people who know about this stuff. :) If I have an SMP box (using -Current specifically) do I want to be compiling things with -lc_r? I'm thinking specifically of mission critical things like apache, but in general will other ports and such take advantage of libc_r if they are compiled with it, or would a program that _can_ take advantage of it already have that built in, say into autoconf or some such? What about other parts of the base system? I'm assuming that the kernel is covered by virtue of the fact that I've enabled the SMP options, yes? I'm trying to learn more about SMP, threads, and such like in general. The recent conversations about those topics on the lists have been very educational. I'm still wading through them, but I appreciate being able to sit on the sidelines and glean bits here and there. Thanks, Doug -- "Welcome to the desert of the real." - Laurence Fishburne as Morpheus, "The Matrix" To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
