On 08/27/2014 02:46 PM, Andrew Morton wrote: > I assume (because I wasn't told!) that there are two objectives here: > > 1) reduce memory consumption by not maintaining pagecache and > 2) reduce CPU cost by avoiding the double-copies. > > These things are pretty easily quantified. And really they must be > quantified as part of the developer testing, because if you find > they've worsened then holy cow, what went wrong. > There are two more huge ones: 3) Writes via mmap are immediately durable (or at least they're durable after a *very* lightweight flush). 4) No page faults ever once a page is writable (I hope -- I'm not sure whether this series actually achieves that goal). A note on #3: there is ongoing work to enable write-through memory for things like this. Once that's done, then writes via mmap might actually be synchronously durable, depending on chipset details. --Andy -- 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>