On Fri, Oct 18, 2013 at 02:07:11PM +0100, Steve Capper wrote: > This patch series implements get_user_pages_fast on ARM. Unlike other > architectures, we do not use IPIs/disabled IRQs as a blocking > mechanism to protect the page table walker. Instead an atomic counter > is used to indicate how many fast gup walkers are active on an address > space, and any code that would cause them problems (THP splitting or > code that could free a page table page) spins on positive values of > this counter. Curious: did you try benchmarking the two schemes? Whilst I expect this algorithm to be better on ARM, exclusive memory accesses aren't free and we're adding code to the fast path. Will -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>