Messages in this thread | | | Date | Fri, 19 Jan 2007 16:26:38 -0500 | From | Bill Davidsen <> | Subject | Re: Threading... |
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Brian McGrew wrote: > On 1/19/07 10:55 AM, "Arjan van de Ven" <arjan@infradead.org> wrote: >> On Fri, 2007-01-19 at 10:43 -0800, Brian McGrew wrote: >>> I have a very interesting question about something that we're seeing >>> happening with threading between Fedora Core 3 and Fedora Core 5. Running >>> on Dell PowerEdge 1800 Hardware with a Xeon processor with hyper-threading >>> turned on. Both systems are using a 2.6.16.16 kernel (MVP al la special). >>> >>> We have a multithreaded application that starts two worker threads. On >>> Fedora Core 3 both of these we use getpid() to get the PID of the thread and >>> then use set_afinity to assign each thread to it's own CPU. Both threads >>> run almost symmetrically even on their given CPU watching the system >>> monitor. >> this is odd; even in FC3 getpid() is supposed to return the process ID >> not the thread ID >> >>> What am I missing? What do I need to do in FC5 or the kernel or the >>> threading library to get my threads to run in symmetric parallel again??? >> you should fix the app to use something like pthread_self() instead... >> (or the highly unportable gettid() but that would just be horrible) > ----- > > And on FC5 I am using pthread_self but my problem isn't simply with > pthread_self, it's with the scheduling. On FC3 both threads run > simultaneously in almost symmetric parallel. On FC5 one thread don't pick > up and start until the previous one is done. On FC3, using getpid for the > thread I could use set_afinity to force each thread to its own processor and > with FC5 I can't; so I've got one idle processor all the time. > This sounds so unlikely I hesitate to mention it, but you are not, by any chance, running pthreads on one and nptl on the other, are you?
-- bill davidsen <davidsen@tmr.com> CTO TMR Associates, Inc Doing interesting things with small computers since 1979 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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