Messages in this thread | | | From | Nick Piggin <> | Subject | Re: [PATCH] undo the brd.c part of ramfs-and-ram-disk-pages-are-unevictable.patch | Date | Fri, 13 Jun 2008 05:08:19 +1000 |
| |
On Friday 13 June 2008 05:00, Lee Schermerhorn wrote: > On Thu, 2008-06-12 at 13:53 -0400, Rik van Riel wrote: > > Undo the brd.c part of ramfs-and-ram-disk-pages-are-unevictable.patch. > > The brd pages do not live on the LRU at all, so there is no need to > > play these tricks. > > Does this mean that these pages cannot be migrated? E.g., to evacuate > memory for hotplug? Looks like all paths to migrate_pages() construct a > list of pages to migrate by isolating them from the lru > [isolate_lru_page()]. Any pages not found in the lru are skipped.
Yes. They have nothing to do with user pages or pagecache pages at all really. brd is now a properly layered block device driver that does not know anything about buffer cache ;)
You can think of the pages it allocates as completely private, and they are used to implement the backing store for the block device.
The vm/fs layers will instantiate buffer cache over this device, which is reclaimable.
| |