send_sigio() scalability

Richard Gooch (rgooch@atnf.csiro.au)
Mon, 17 May 1999 13:17:59 +1000

Hi, all. I just noticed that send_sigio() walks the task list,
looking for the process(es) to send a signal to. This appears to be a
potential scalability problem, as a large number of tasks is going to
slow this down.

Has anyone done any benchmarking to evaluate the effect of this? In
the absence of numbers, how about some convincing handwaving? Is it
worth exploring options to fix this?

I can think of one quick and simple hack to fix this for 90% (maybe
99%) of cases: record the task pointer at fcntl() time. Then at
send_sigio() time, if the recorded pid and task match, skip the
task list walk.

Regards,

Richard....

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