Messages in this thread | | | Date | Wed, 19 Mar 2008 02:04:40 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH prototype] [0/8] Predictive bitmaps for ELF executables |
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On Wed, 19 Mar 2008 09:32:28 +0100 Andi Kleen <andi@firstfloor.org> wrote:
> On Tue, Mar 18, 2008 at 10:44:37AM -0700, Andrew Morton wrote: > > On Tue, 18 Mar 2008 18:20:45 +0100 Andi Kleen <andi@firstfloor.org> wrote: > > > > > > What's the permission problem? executable-but-not-readable files? Could > > > > > > Not writable. > > > > Oh. > > > > I doubt if a userspace implementation would even try to alter the ELF > > files, really - there seems to be no point in it. This is just complexity > > Well the information has to be somewhere and i think the ELF file > is the best location for it. It makes it the most user transparent.
Adopt a standard, stick with it.
Assuming that all users have the same access pattern might be inefficient, a little bit. There might be some advantage to making it per-user, dunno.
The requirement to write to an executable sounds like a bit of a showstopper.
> > > Yes it could, but i dont even want to thi nk about all the issues of > > > doing such an interface. It is basically an microkernelish approach. > > > I prefer monolithic simplicity. > > > > It's not complex at all. Pass a null-terminated pathname to the server and > > keep running. The server will asynchronously read your pages for you. > > But how do you update the bitmap in your scheme?
umm,
BITMAP_TRAINING_RUN=1 /usr/lib64/firefox-2.0.0.12/firefox-bin
will write the bitmap to ~/.bitmaps/usr/lib64/firefox-2.0.0.12/firefox-bin ?
if it proves useful, build it all into libc..
I'm assuming that the per-page minor fault cost is relatively low and that the major benefit is in disk scheduling[*]. If that's false then we'd need kernel support I guess - some sort of gang-fault syscall?
* solid-state disks are going to put a lot of code out of a job.
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