On Tue 28-11-17 14:12:15, Yafang Shao wrote: > 2017-11-28 11:11 GMT+08:00 Yafang Shao <laoar.shao@xxxxxxxxx>: > > Hi Michal, > > > > What about bellow change ? > > It makes the function domain_dirty_limits() more clear. > > And the result will have a higher precision. > > > > > > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > > index 8a15511..2b5e507 100644 > > --- a/mm/page-writeback.c > > +++ b/mm/page-writeback.c > > @@ -397,8 +397,8 @@ static void domain_dirty_limits(struct > > dirty_throttle_control *dtc) > > unsigned long bytes = vm_dirty_bytes; > > unsigned long bg_bytes = dirty_background_bytes; > > /* convert ratios to per-PAGE_SIZE for higher precision */ > > - unsigned long ratio = (vm_dirty_ratio * PAGE_SIZE) / 100; > > - unsigned long bg_ratio = (dirty_background_ratio * PAGE_SIZE) / 100; > > + unsigned long ratio = vm_dirty_ratio; > > + unsigned long bg_ratio = dirty_background_ratio; > > unsigned long thresh; > > unsigned long bg_thresh; > > struct task_struct *tsk; > > @@ -416,28 +416,33 @@ static void domain_dirty_limits(struct > > dirty_throttle_control *dtc) > > */ > > if (bytes) > > ratio = min(DIV_ROUND_UP(bytes, global_avail), > > - PAGE_SIZE); > > + 100); > > if (bg_bytes) > > bg_ratio = min(DIV_ROUND_UP(bg_bytes, global_avail), > > - PAGE_SIZE); > > + 99); /* bg_ratio should less than ratio */ > > bytes = bg_bytes = 0; > > } > > > Errata: > > if (bytes) > - ratio = min(DIV_ROUND_UP(bytes, global_avail), > - PAGE_SIZE); > + ratio = min(DIV_ROUND_UP(bytes / PAGE_SIZE, global_avail), > + 100); > if (bg_bytes) > - bg_ratio = min(DIV_ROUND_UP(bg_bytes, global_avail), > - PAGE_SIZE); > + bg_ratio = min(DIV_ROUND_UP(bg_bytes / PAGE_SIZE, global_avail), > + 100 - 1); /* bg_ratio should be less than ratio */ > bytes = bg_bytes = 0; And you really think this makes code easier to follow? I am somehow not conviced... -- Michal Hocko SUSE Labs -- 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>
