Messages in this thread | | | Subject | Re: Synchronization primitives in UML (was: Re: [uml-devel] Re: [patch 09/20] uml: use SIG_IGN for empty sighandler) | Date | Tue, 09 Nov 2004 15:48:45 -0500 | From | Jeff Dike <> |
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blaisorblade_spam@yahoo.it said: > I also understand now what all this is for. When I have time for this, > I'll at least copy and paste your mail into a comment, with any > needed adjustment.
That would be a good idea.
> For the semaphore issue, I have some ideas (like using futexes) which > need to be developed a bit:
> 1) I want to create a semaphore API in os_*. > 2) It will be able to use socketpairs. > 3) It will be able to use futexes, if they are > non-persistant and usable without too much issues (the same way we > are going to support Async I/O). > 4) It will be used first by the code > which could really benefit from the performance increase. > 5) It won't > use persistant objects.
This all sounds good, although there are simplicity benefits to just using one underlying mechanism, as long as there are no overriding disadvantages to it.
> Any comment on these issues? Also, apart TT context switching, is > there any other performance-sensitive use of semaphores, which would > benefit from using futexes?
Offhand, I think context switching is the most sensitive one.
> Yes, semget and friends are uglier. > But don't think that the current nested code is simple to read - three > semaphores at a time, without a clear name, are not the clearer code > on the world.
What nested code are you talking about?
Jeff
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