On Thu, 23 May 2013, Peter Zijlstra wrote: > The patch completely fails to explain how RLIMIT_LOCKED is supposed to > deal with pinned vs locked. Perf used to account its pages against > RLIMIT_LOCKED, with the patch it compares pinned against RLIMIT_LOCKED > but completely discards any possible locked pages. Pinned pages are different from mlock. Mlock semantics means that the pages are kept in memory but the pages are movable (subject to page migration f.e.). Pinned pages have to stay where they are since the physical addresses may be used for device I/O or other stuff. Both pinned and mlocked pages cannot be evicted from memory. If one wants to account for unevictable pages then both are contributing. However, since a pinned page may be mlocked simply adding up the counter may cause problems. The sum could be used as a worst case estimate though. We could mlock all pinned pages but then the issue arises on how to track that properly in order to unpin when the I/O action is done since the app may have also mlocked pages. -- To unsubscribe from this list: send the line "unsubscribe trinity" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
