Re: Threads and SMP kernel scheduling
Hi, Thank you very much again Ulf. I found this http://en.wikipedia.org/wiki/Native_POSIX_Thread_Library and it describes 1:1 correspondence of Linux threads. So, you were right and thank you very much again. Regards, Mehmet On Thu, Jan 8, 2009 at 4:59 PM, Ulf Lilleengen ulf.lilleen...@gmail.comwrote: On tor, jan 08, 2009 at 09:16:26am -0500, Mehmet Ali Aksoy TÜYSÜZ wrote: Hi, Thank you very much for your response Ulf. It is a very clear answer. Thanks again. By the way, any information for the Linux case? I think this applies to Linux as well, since it's NPTL(Native Posix Threading Library) uses a 1:1 mapping also. I'm not 100% sure, so you might want to ask on a linux mailing list. -- Ulf Lilleengen ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Threads and SMP kernel scheduling
Hi all, After I had a bit googling I got confused. My questions are simple and they are as follows : 1-) Are pthreads (or threads in general) of one process scheduled to different cores on multi-core systems running Linux or BSD? 2-) What if there are multiple processes which have multiple threads? Does it change the answer of (1)? I found some answers but they are not sharp. Somebody says can be scheduled but can be is not a precise answer (in my opinion.) Thanks everybody in advance. Mehmet ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: Threads and SMP kernel scheduling
On Thu, Jan 08, 2009 at 04:23:08AM -0500, Mehmet Ali Aksoy TÜYSÜZ wrote: Hi all, After I had a bit googling I got confused. My questions are simple and they are as follows : 1-) Are pthreads (or threads in general) of one process scheduled to different cores on multi-core systems running Linux or BSD? The standard threading library in FreeBSD will use a 1:1 mapping between userland threads(pthreads) and kernel threads. This means that each thread may run on a different core than other threads. 2-) What if there are multiple processes which have multiple threads? Does it change the answer of (1)? No, the same mapping applies. Although threads of one process may preferably run on the same core, each thread of a process may run on any of the cores available. I found some answers but they are not sharp. Somebody says can be scheduled but can be is not a precise answer (in my opinion.) Well, it means that there are more factors deciding where a thread is put. If you look at a factor such as affinity, one thread may preferable be scheduled to the same core since the cache may contain data relevant to the thread. Thanks everybody in advance. Hope everything is at least a bit clearer. -- Ulf Lilleengen ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: Threads and SMP kernel scheduling
Hi, Thank you very much for your response Ulf. It is a very clear answer. Thanks again. By the way, any information for the Linux case? Regards, Mehmet On Thu, Jan 8, 2009 at 10:08 AM, Ulf Lilleengen ulf.lilleen...@gmail.comwrote: On Thu, Jan 08, 2009 at 04:23:08AM -0500, Mehmet Ali Aksoy TÜYSÜZ wrote: Hi all, After I had a bit googling I got confused. My questions are simple and they are as follows : 1-) Are pthreads (or threads in general) of one process scheduled to different cores on multi-core systems running Linux or BSD? The standard threading library in FreeBSD will use a 1:1 mapping between userland threads(pthreads) and kernel threads. This means that each thread may run on a different core than other threads. 2-) What if there are multiple processes which have multiple threads? Does it change the answer of (1)? No, the same mapping applies. Although threads of one process may preferably run on the same core, each thread of a process may run on any of the cores available. I found some answers but they are not sharp. Somebody says can be scheduled but can be is not a precise answer (in my opinion.) Well, it means that there are more factors deciding where a thread is put. If you look at a factor such as affinity, one thread may preferable be scheduled to the same core since the cache may contain data relevant to the thread. Thanks everybody in advance. Hope everything is at least a bit clearer. -- Ulf Lilleengen ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
Re: Threads and SMP kernel scheduling
On tor, jan 08, 2009 at 09:16:26am -0500, Mehmet Ali Aksoy TÜYSÜZ wrote: Hi, Thank you very much for your response Ulf. It is a very clear answer. Thanks again. By the way, any information for the Linux case? I think this applies to Linux as well, since it's NPTL(Native Posix Threading Library) uses a 1:1 mapping also. I'm not 100% sure, so you might want to ask on a linux mailing list. -- Ulf Lilleengen ___ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to freebsd-hackers-unsubscr...@freebsd.org
