Messages in this thread | | | Date | Sat, 7 May 2016 13:40:57 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch V2 3/7] futex: Add op for hash preallocation |
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On Sat, 7 May 2016, Thomas Gleixner wrote: > On Fri, 6 May 2016, Darren Hart wrote: > > > Note, that this call must be issued before the first futex operation in the > > > process because that would automatically allocate the default sized hash. > > > > So this seems like it could be tricky for the user as system libraries, like > > glibc, make use of futexes. Can we guarantee that "sys_futex" is not called by > > the time main() is called? > > To the extent of my testing I never observed that the hash was automatically > created when I called futex(PREALLOC) right away in main. But yes, that might > need some thought.
Thinking more about it. If a process is single threaded and it definitely is up to the point where it reaches main(), there is nothing which might cause a sys_futex() call except something which would use shared futexes in the depth of init code. I doubt that this happens, and if it does, then it's some non standard feature^Whackery which I do not care about at all.
Thanks,
tglx
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