On Fri, 2015-03-06 at 11:32 -0800, Linus Torvalds wrote: > IOW, I wonder if we could special-case the common non-IO > fault-handling path something along the lines of: > > - look up the vma in the vma lookup cache
But you'd still need mmap_sem there to at least get the VMA's first value. > - look up the page in the page cache > - get the page table spinlock > - re-check the vma now (it ends up being stable if it can't be torn > down due to the page table spinlock) > > because I suspect that page faults are the biggest users of that > mmap_sem, and we could probably handle a fairly large common case > (making it simpler by special-casing it and punting in any even > _slightly_ complicated situations) without even getting the semaphore > at all, since we have to serialize on the actual page table *anyway*. > > Basically, to me, the whole "if a lock is so contended that we need to > play locking games, then we should look at why we *use* the lock, > rather than at the lock itself" is a religion. > > Linus > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
