Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] Linux-2.5 fix/improve get_pid() | Date | 8 Aug 2002 14:30:35 -0700 |
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Followup to: <Pine.LNX.4.44.0208081312330.8705-100000@home.transmeta.com> By author: Linus Torvalds <torvalds@transmeta.com> In newsgroup: linux.dev.kernel > > Guys, this discussion is getting ridiculous. > > Doing a bit allocator should be trivial, but it's hard to know when a bit > is to be free'd. You can't just do it at "exit()" time, because even if > pid X exits, that doesn't mean that X can be re-used: it may still be used > as a pgid or a tid by some other process Y. > > So if you really want to take this approach, you need to count the uses of > "pid X", and free the bitmap entry only when that count goes to zero. I > see no such logic in Bill Irwin's code, only a comment about last use > (which doesn't explain how to notice that last use). >
Even so, we need to maintain Not Recently Used semantic. A discussion on #kernel seems to have ended up with recommending a design target of "no pid reuse within 30 seconds", with 1 second being an absolute requirement.
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