Messages in this thread | | | Date | Mon, 22 Nov 2004 12:56:34 -0600 | From | Ray Bryant <> | Subject | Re: [Lse-tech] scalability of signal delivery for Posix Threads |
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Andi Kleen wrote: > On Mon, Nov 22, 2004 at 05:51:59PM +0100, Andreas Schwab wrote: > >>Andi Kleen <ak@suse.de> writes: >> >> >>>At least in traditional signal semantics you have to call sigaction >>>or signal in each signal handler to reset the signal. So that >>>assumption is not necessarily true. >> >>If you use sigaction then you get POSIX semantics, which don't have this >>problem. > > > It's just a common case where Ray's assumption is not true. > > -Andi >
True enough. And in that case the design that I was describing wouldn't make sigaction() that much more expensive since if you are not in the POSIX thread environment (more precisely, the thread was not created with CLONE_SIGHAND) each thread has its own sighand structure and the "global" locking mechanisum I had proposed would only require the taking of one additional lock.
However, special casing ITIMER_PROF is also a reasonable avenue of approach. The performance monitor code can also deliver signals to user space when a sampling buffer overflows, and this can have the same kind of scaling problem as ITIMER_PROF. I'll have to do a little research to figure out how exactly that works, but that signal (SIGIO?) would also be a candidate for special casing on our platform.
-- Best Regards, Ray ----------------------------------------------- Ray Bryant 512-453-9679 (work) 512-507-7807 (cell) raybry@sgi.com raybry@austin.rr.com The box said: "Requires Windows 98 or better", so I installed Linux. ----------------------------------------------- - 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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