On Thu, Jul 19, 2018 at 05:15:55PM +0200, Michal Hocko wrote: > Your changelog doesn't really explain the motivation. Does the change > help performance? Is this a pure cleanup?
Hi Michal, Sorry to not have explained this better from the very beginning. It should help a bit in performance terms as we would be skipping those condition checks and assignations for zones that do not have any pages. It is not a huge win, but I think that skipping code we do not really need to run is worh to have. > The function is certainly not an example of beauty. It is more an > example of changes done on top of older ones without much thinking. But > I do not see your change would make it so much better. I would consider > it a much nicer cleanup if it was split into logical units each doing > one specific thing. About the cleanup, I thought that moving that block of code to a separate function would make the code easier to follow. If you think that this is still not enough, I can try to split it and see the outcome. > Btw. are you sure this change is correct? E.g. > /* > * Set an approximate value for lowmem here, it will be adjusted > * when the bootmem allocator frees pages into the buddy system. > * And all highmem pages will be managed by the buddy system. > */ > zone->managed_pages = is_highmem_idx(j) ? realsize : freesize; > > expects freesize to be calculated properly and just from quick reading > the code I do not see why skipping other adjustments is ok for size > 0. > Maybe this is OK, I dunno and my brain is already heading few days off > but a real cleanup wouldn't even make me think what the heck is going on > here. This changed in commit e69438596bb3e97809e76be315e54a4a444f4797. Current code does not have "realsize" anymore. Thanks -- Oscar Salvador SUSE L3
