Messages in this thread | | | Date | Sun, 11 Apr 2010 00:35:29 +0100 | From | Alan Cox <> | Subject | Re: [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning |
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> The non-swappable part will be tricky. One doesn't know how many > threads will be created in a process. This mechanism shouldn't put an > arbitrary limit in place. So where to allocate the memory? Perhaps > it's better to implicitly mark the memory page pointed to by the new > syscall as non-swappable? This could mean one page per thread...
You only need one page per 4096 threads or so if you make it create the page on the first request, tied to say the signals and the like in threaded tasks, and you then allocate 'slots' in the page for future calls until you've got 4096 live.
ie you'd see something like
addr = set_tid_notifier_addr();
[1st call map page at x to x + 4095, probably R/O] [returns x]
next thread addr = set_tid_notifier_addr()
[returns x + 1]
Alan
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