On Sat, Aug 18, 2007 at 04:45:31PM +0800, Fengguang Wu wrote: > Matt, > > On Sat, Aug 18, 2007 at 01:40:42AM -0500, Matt Mackall wrote: > > > - On memory pressure, > > > - as VSZ goes up, RSS will be bounded by physical memory. > > > So VSZ:RSS ratio actually goes up with memory pressure. > > > > And yes. > > > > But that's not what I'm talking about. You're likely to have more > > holes in your ranges with memory pressure as things that aren't active > > get paged or swapped out and back in. And because we're walking the > > LRU more rapidly, we'll flip over a lot of the active bits more often > > which will mean more output. > > > > > - page range is a good unit of locality. They are more likely to be > > > reclaimed as a whole. So (RSS:page_ranges) wouldn't degrade as much. > > > > There is that. The relative magnitude of the different effects is > > unclear. But it is clear that the worst case for pmap is much worse > > > than pagemap (two lines per page of RSS?). > It's one line per page. No sane app will make vmas proliferate.
Sane apps are few and far between. > So let's talk about the worst case. > > pagemap's data set size is determined by VSZ. > 4GB VSZ means 1M PFNs, hence 8MB pagemap data. > > pmaps's data set size is bounded by RSS hence physical memory. > 4GB RSS means up to 1M page ranges, hence ~20M pmaps data. > Not too bad :) Hmmm, I've been misreading the output. What does it do with nonlinear VMAs? -- Mathematics is the supreme nostalgia of our time. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
