On Fri, 19 Aug 2022 10:47:58 +0800 haoxin <xhao@xxxxxxxxxxxxxxxxx> wrote: > > 在 2022/8/19 上午10:28, SeongJae Park 写道: > > Hi Xin, > > > >> 在 2022/8/19 上午1:11, SeongJae Park 写道: > >>> Hi Xin, > >>> > >>> > >>> On Thu, 18 Aug 2022 18:57:31 +0800 Xin Hao <xhao@xxxxxxxxxxxxxxxxx> wrote: > >>> > >>>> In damon_lru_sort_apply_parameters(), if "monitor_region_start" > >>>> and "monitor_region_end" is not a valid physical address range, > >>>> There no need to run the remainder codes in it. > >>> The function, 'damon_lru_sort_apply_parameters()', checks validity of > >>> parameters and construct the DAMON context one by one. For example, > >>> 'damon_set_attrs()' returns an error if the parameters are invalid. So the > >>> intended flow is, > >>> > >>> 1. check DAMON attributes parameters, > >>> 2. apply DAMON attributes parameters, > >>> 3. check scheme parameters, > >>> 4. apply scheme parameters, > >>> 5. check target region parameters, and > >>> 6. apply target region parameters. > >>> > >>> Therefore what this patch does is making the target regions validity check to > >>> be done earlier than validity checks of other parameters. There is no special > >>> reason to check the region earlier than others. Also, this change makes the > >>> flow of the function a little bit weird in my humble opinion, as the flow will > >>> be > >>> > >>> 1. check target region parameters, > >>> 2. check DAMON attributes parameters, > >>> 3. apply DAMON attributes parameters, > >>> 4. check scheme parameters, > >>> 5. apply scheme parameters, and > >>> 6. apply target region parameters. > >> Ok, understand what you mean, my fix looks ugly, buy any apply above > >> are not not necessary if one of them checks failed, why not check all > >> fisrt and then apply them, like this: > >> > >> 1. check target region parameters, > >> > >> 2. check DAMON attributes parameters, > >> > >> 3. check scheme parameters, > > The parameter values could be changed by users after the check, so we should > > cache those somewhere anyway. In other words, we cache those in the DAMON > > context. Therefore I think the above works were not totally waste of the time. > > Also, because the parameters applying functions like 'damon_set_attrs()' does > > the check and applying of the parameters together, I feel like current flow is > > natural. > > Ok, Thank you for your detailed explain, just keep it. but there still > a problem in damon_lru_sort_apply_parameters > > if (!monitor_region_start && !monitor_region_end && > !get_monitoring_region(&monitor_region_start, > &monitor_region_end)) > > if (!monitor_region_start || !monitor_region_end || > !get_monitoring_region(&monitor_region_start, > &monitor_region_end)) > > the '&&' should fix to '||', anyone checks fail, it should return ? No. The code is for setting the monitoring region as the biggest System RAM resource only if the user didn't set both 'monitor_region_start' and 'monitor_region_end'. Thanks, SJ
