On Thu, May 19, 2016 at 02:28:49PM +0200, Peter Zijlstra wrote: > On Sat, May 07, 2016 at 10:47:38AM +0200, Thomas Gleixner wrote: > > On Fri, 6 May 2016, Darren Hart wrote: > > > > 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. > > I suspect that even if glibc uses futexes before main(), they will not > be contended, because, last time I checked, the C runtime environment is > very much single threaded unless explicitly made not so by the program. > > In any case (re)hashing if the hash is empty is 'easy', if there's already > state, > not so much.
It certainly would be nice to be able to resize the hash if it's empty. -- Darren Hart Intel Open Source Technology Center
