Messages in this thread | | | Date | Fri, 19 Aug 2022 10:47:58 +0800 | Subject | Re: [PATCH V2 1/2] mm/damon/lru_sort: Move target memory region check to head of func | From | haoxin <> |
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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@linux.alibaba.com> 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 ?
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