Messages in this thread | | | Date | Wed, 7 Aug 2019 11:34:34 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH 4/4] writeback, memcg: Implement foreign dirty flushing |
| |
Hello,
On Tue, Aug 06, 2019 at 04:03:06PM -0700, Andrew Morton wrote: > > + if (i < MEMCG_CGWB_FRN_CNT) { > > + unsigned long update_intv = > > + min_t(unsigned long, HZ, > > + msecs_to_jiffies(dirty_expire_interval * 10) / 8); > > An explanation of what's going on here would be helpful. > > Why "* 1.25" and not, umm "* 1.24"?
Just because /8 is cheaper. It's likely that a fairly wide range of numbers are okay for the above. I'll add some comment to explain that and why the specific constants are picked.
> > +void mem_cgroup_flush_foreign(struct bdi_writeback *wb) > > +{ > > + struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); > > + unsigned long intv = msecs_to_jiffies(dirty_expire_interval * 10); > > Ditto.
This is just dirty expiration. If the dirty data has expired, writeback must already be in progress by its bdi_wb, so there's no reason to scheduler foreign writeback. Will add a comment.
Thanks.
-- tejun
| |