Messages in this thread | | | Date | Thu, 31 Dec 2009 08:43:39 +0000 (GMT) | From | Hugh Dickins <> | Subject | Re: [PATCH 2/3 -mmotm-2009-12-10-17-19] Count zero page as file_rss |
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On Thu, 31 Dec 2009, Minchan Kim wrote: > On Thu, Dec 31, 2009 at 1:49 AM, Hugh Dickins > <hugh.dickins@tiscali.co.uk> wrote: > > > > You are right that I completely overlooked the issue of whether to > > include the ZERO_PAGE in rss counts (now being a !vm_normal_page, > > it was just natural to leave it out); and I overlooked the fact that > > it used to be counted into file_rss in the old days (being !PageAnon). > > > > So I'm certainly at fault for that, and thank you for bringing the > > issue to attention; but once considered, I can't actually see a good > > reason why we should add code to count ZERO_PAGEs into file_rss now. > > And if this patch falls, then 1/3 and 3/3 would fall also. > > > > And the patch below would be incomplete anyway, wouldn't it? > > There would need to be a matching change to zap_pte_range(), > > but I don't see that. > > Thanks. > If we think this patch is need, I will repost path with fix it. > > What do you think?
If someone comes up with a convincing case in which their system is behaving significantly worse because the zero page is not being counted in rss now, then we shall probably want your patch.
But I still don't yet see a reason to add code just to keep the anon_rss+file_rss number looking the same as it was before, in this exceptional case where there's a significant number of zero pages.
Hugh
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