Messages in this thread | | | Date | Sun, 10 May 2009 22:56:27 +0900 | Subject | Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen | From | KOSAKI Motohiro <> |
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Hi
>> 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.
hmm I don't think this patch change JIT behavior. JIT makes large executable _anon_ pages. but page_mapping(anon-page) return NULL.
Thus, the logic do nothing.
> 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.
true. My SSD have high speed random reading charactastics.
> 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.
Yes, mesurement is essential.
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