On Fri, Feb 07, 2014 at 11:30:02AM +0100, Vlastimil Babka wrote: > On 02/07/2014 06:08 AM, Joonsoo Kim wrote: > > isolation_suitable() and migrate_async_suitable() is used to be sure > > that this pageblock range is fine to be migragted. It isn't needed to > > call it on every page. Current code do well if not suitable, but, don't > > do well when suitable. It re-check it on every valid pageblock. > > This patch fix this situation by updating last_pageblock_nr. > > It took me a while to understand that the problem with migrate_async_suitable() was the > lack of last_pageblock_nr updates (when the code doesn't go through next_pageblock: > label), while the problem with isolation_suitable() was the lack of doing the test only > when last_pageblock_nr != pageblock_nr (so two different things). How bout making it > clearer in the changelog by replacing the paragraph above with something like: Really nice!! Sorry for bad description and thanks for taking time to understand it. > > <snip> > isolation_suitable() and migrate_async_suitable() is used to be sure > that this pageblock range is fine to be migragted. It isn't needed to > call it on every page. Current code do well if not suitable, but, don't > do well when suitable. > > 1) It re-checks isolation_suitable() on each page of a pageblock that was already > estabilished as suitable. > 2) It re-checks migrate_async_suitable() on each page of a pageblock that was not entered > through the next_pageblock: label, because last_pageblock_nr is not otherwise updated. > > This patch fixes situation by 1) calling isolation_suitable() only once per pageblock and > 2) always updating last_pageblock_nr to the pageblock that was just checked. > </snip> > > > Additionally, move PageBuddy() check after pageblock unit check, > > since pageblock check is the first thing we should do and makes things > > more simple. > > You should also do this, since it becomes redundant and might only confuse people: > > next_pageblock: > low_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages) - 1; > - last_pageblock_nr = pageblock_nr; > Okay. > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > With the above resolved, consider the patch to be > > Acked-by: Vlastimil Babka <vbabka@xxxxxxx> I will do it. 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>