On Mon, 29 Jun 2020 09:57:42 -0700 Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote: > > > I am okay with Matthew's suggestion of keeping the stack pagevec size unchanged. > Andrew, do you have a preference? > > I was assuming that for people who really care about saving the kernel memory > usage, they would make CONFIG_NR_CPUS small. I also have a hard time coming > up with a better scheme. > > Otherwise, we will have to adjust the pagevec size when we actually > found out how many CPUs we have brought online. It seems like a lot > of added complexity for going that route. Even if we were to do this, the worst-case stack usage on the largest systems might be an issue. If it isn't then we might as well hard-wire it to 31 elements anyway, I dunno. An extra 128 bytes of stack doesn't sound toooo bad, and the performance benefit is significant. Perhaps we just go with the original patch. If there are any on-stack pagevecs in the page reclaim path then perhaps we could create a new mini-pagevec for just those. or look at simply removing the pagevec optimization in there altogether.
