Messages in this thread | | | Date | Sun, 10 May 2009 14:45:33 +0100 | From | Alan Cox <> | Subject | Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen |
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On Sun, 10 May 2009 18:36:19 +0900 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote: > I don't oppose this policy. PROT_EXEC seems good viewpoint.
I don't think it is that simple
Not only can it be abused but some systems such as java have large PROT_EXEC mapped environments, as do many other JIT based languages.
Secondly it moves the pressure from the storage volume holding the system binaries and libraries to the swap device which already has to deal with a lot of random (and thus expensive) I/O, as well as the users filestore for mapped objects there - which may even be on a USB thumbdrive.
I still think the focus is on the wrong thing. We shouldn't be trying to micro-optimise page replacement guesswork - we should be macro-optimising the resulting I/O performance. My disks each do 50MBytes/second and even with the Gnome developers finest creations that ought to be enough if the rest of the system was working properly.
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