Messages in this thread | | | Date | Fri, 8 May 2009 15:15:32 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen |
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On Fri, 8 May 2009 23:00:45 +0100 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> > The patch seems reasonable but the changelog and the (non-existent) > > design documentation could do with a touch-up. > > Is it right that I as a user can do things like mmap my database > PROT_EXEC to get better database numbers by making other > stuff swap first ? > > You seem to be giving everyone a "nice my process up" hack.
Yep.
But prior to 2.6.27(?) the same effect could be had by mmap()ing the file with or without PROT_EXEC. The patch restores a probably-beneficial heuristic which got lost in the LRU rewrite.
So we're no worse than pre-2.6.27 kernels here. Plus there are probably more effective ways of getting that sort of boost, such as having a process running which simply touches your favoured pages at a suitable (and fairly low) frequency.
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