On 22 December 2014 at 06:43, David Gwynne <da...@gwynne.id.au> wrote: > this introduces a global gc task that loops over all the pools > looking for pages that havent been used for a very long time so > they can be freed. > > this is the simplest way of doing this without introducing per pool > timeouts/tasks which in turn could introduce races with pool_destroy, > or more shared global state that gets touched on pool_get/put ops. > > im adding the timeout in src/sys/kern/init_main.c cos having pool_init > do it causes faults when a pool is created before the timeout > subsystem is set up. > > i have tested this on sparc64, amd64, and hppa, and it seems to do > the advertised job. >
i have a couple of questions to understand the reasoning behind this. 1) how is it different from what we have now? 2) why can't you do it when you pool_put? 3) why can't you call it from uvm when there's memory pressure since from what i understand pool_reclaim was supposed to work like that? 4) i assume you don't want to call pool_reclaim from pool_gc_pages because of the mutex_enter_try benefits, but why does logic in these functions differ, e.g. why did you omit the pr_itemsperpage bit? 5) why 8 ticks is a "very long time" to free a page? why not 10 seconds? 6) why is there an XXX next to the splx? 7) it looks like pool_reclaim_all should also raise an IPL since it does the same thing. wasn't it noteced before?
