On 2 Aug 2002, Alan Cox wrote:
> The numbers look very different on a real processor. Signal delivery is
> indeed not stunningly fast but relative to a context switch its very low
> indeed.
actually the opposite is true, on a 2.2 GHz P4:
$ ./lat_sig catch
Signal handler overhead: 3.091 microseconds
$ ./lat_ctx -s 0 2
2 0.90
ie. *process to process* context switches are 3.4 times faster than signal
delivery. Ie. we can switch to a helper thread and back, and still be
faster than a *single* signal.
signals are in essence 'lightweight' threads created and destroyed for the
purpose of a single asynchronous event, it's IMO a very inefficient and
baroque concept for almost anything (but debugging and a number of very
special uses). I'd guess that with a sane threading library a helper
thread is faster for almost everything.
Ingo
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This archive was generated by hypermail 2b29 : Wed Aug 07 2002 - 22:00:21 EST