On Wed, 4 Apr 2007, Rik van Riel wrote: > Hugh Dickins wrote: > > > (I didn't understand how Rik would achieve his point 5, _no_ lock > > contention while repeatedly re-marking these pages, but never mind.) > > The CPU marks them accessed&dirty when they are reused. > > The VM only moves the reused pages back to the active list > on memory pressure. This means that when the system is > not under memory pressure, the same page can simply stay > PG_lazyfree for multiple malloc/free rounds.
Sure, there's no need for repetitious locking at the LRU end of it; but you said "if the system has lots of free memory, pages can go through multiple free/malloc cycles while sitting on the dontneed list, very lazily with no lock contention". I took that to mean, with userspace repeatedly madvising on the ranges they fall in, which will involve mmap_sem and ptl each time - just in order to check that no LRU movement is required each time. (Of course, there's also the problem that we don't leave our systems with lots of free memory: some LRU balancing decisions.) Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
