From: SeongJae Park <sjpark@xxxxxxxxx> Hi Amit, On Fri, 11 Jun 2021 12:55:27 +0000 "Shah, Amit" <aams@xxxxxxxxx> wrote: > On Thu, 2021-05-20 at 07:56 +0000, SeongJae Park wrote: > > From: SeongJae Park <sjpark@xxxxxxxxx> > > > > PG_idle and PG_young allow the two PTE Accessed bit users, Idle Page > > Tracking and the reclaim logic concurrently work while don't interfere > > ... while not interfering with ... Will fix so. > > > each other. That is, when they need to clear the Accessed bit, they set > > PG_young to represent the previous state of the bit, respectively. And > > when they need to read the bit, if the bit is cleared, they further read > > the PG_young to know whether the other has cleared the bit meanwhile or > > not. > > > > We could add another page flag and extend the mechanism to use the flag > > if we need to add another concurrent PTE Accessed bit user subsystem. > > However, the space is limited. Meanwhile, if the new subsystem is > > mutually exclusive with IDLE_PAGE_TRACKING or interfering with it is not > > a real problem, it would be ok to simply reuse the PG_idle flag. > > However, it's impossible because the flags are dependent on > > IDLE_PAGE_TRACKING. > > For better readability, I suggest: > > For yet another user of the PTE Accessed bit, we could add another page > flag, or extend the mechanism to use the flags. For the DAMON usecase, > however, we don't need to do that just yet. IDLE_PAGE_TRACKING and > DAMON are mutually exclusive, so there's only ever going to be one user > of the current set of flags. > > In this commit, we split out the CONFIG options to allow for the use of > PG_young and PG_idle outside of idle page tracking. Thank you for the suggestion, it looks better to me, either. I will update so in the next spin. Thanks, SeongJae Park [...]
