On Thu, Dec 03, 2015 at 11:36:52AM +0100, Vlastimil Babka wrote: > On 12/03/2015 08:11 AM, Joonsoo Kim wrote: > > Cached pfn is used to determine the start position of scanner > > at next compaction run. Current cached pfn points the skipped pageblock > > so we uselessly checks whether pageblock is valid for compaction and > > skip-bit is set or not. If we set scanner's cached pfn to next pfn of > > skipped pageblock, we don't need to do this check. > > > > This patch moved update_pageblock_skip() to > > isolate_(freepages|migratepages). Updating pageblock skip information > > isn't relevant to CMA so they are more appropriate place > > to update this information. > > That's step in a good direction, yeah. But why not go as far as some variant of > my (not resubmitted) patch "mm, compaction: decouple updating pageblock_skip and > cached pfn" [1]. Now the overloading of update_pageblock_skip() is just too much > - a struct page pointer for the skip bits, and a pfn of different page for the > cached pfn update, that's just more complex than it should be. > > (I also suspect the pageblock_flags manipulation functions could be simpler if > they accepted zone pointer and pfn instead of struct page) Okay. > Also recently in Aaron's report we found a possible scenario where pageblocks > are being skipped without entering the isolate_*_block() functions, and it would > make sense to update the cached pfn's in that case, independently of updating > pageblock skip bits. > > But this might be too out of scope of your series, so if you want I can > separately look at reviving some useful parts of [1] and the simpler > pageblock_flags manipulations. I will cherry-pick some useful parts of that with your authorship and respin this series after you finish to review all patches. Thanks. -- 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>