On Tue, Oct 23, 2012 at 02:30:45PM -0700, Andrew Morton wrote:
> >
> > The data is encoded in a somewhat awkward two letters mnemonic form, to
> > encourage userspace to be prepared for fields being added or removed in
> > the future.
> >
>
> Wow. This version generates 1k less kernel bloat than v2! Gee, and I
> only sent that email as a late-night joke ;)
Cool!
> fs/proc/task_mmu.o with neither patch:
> text data bss dec hex filename
> 14849 112 5312 20273 4f31 fs/proc/task_mmu.o
>
> fs/proc/task_mmu.o with the v2 patch:
> 16074 112 5776 21962 55ca fs/proc/task_mmu.o
>
> fs/proc/task_mmu.o with the v3 patch:
> 15446 112 5368 20926 51be fs/proc/task_mmu.o
>
> fs/proc/task_mmu.o with the v3 patch and the below fix:
> 15123 112 5352 20587 506b fs/proc/task_mmu.o
>
> So the delta has gone from 1700 bytes down to 300. Seems that it pays
> to be anal about these things ;)
LOL ;-)
> Don't forget the `static'! Without it, the compiler will need to
Yeah, for some reason missed it, thanks!
> construct the array as a temporary on the stack each time the function
> is called - it's just terrible. (There's no reason why the compiler
> can't insert the static for us as an optimisation, and I think later
> gcc's may have got smarter about this).
>
> Was there a reason why you added the ".l = " to the initialiser? My
> gcc is happy without it.
Mine either, just as habbit I would say, thanks.
> Also... what happens if there's an unrecognised bit set in `flags'?
> Memory corruption or code skew could cause this. We emit a couple of
> NULs into the procfs output, which I guess is an OK response to such a
> condition.
That's indeed will produce some nil character on the screen. I guess we
need some designited init here, say
[0 ... (BITS_PER_LONG-1)] = { {'-', '-'} },
...
[ilog2(VM_READ)] = { {'r', 'd'} },
...
and so on, i'll update on top
> From: Andrew Morton <[email protected]>
> Subject: procfs-add-vmflags-field-in-smaps-output-v3-fix
>
> make mnemonics[] static, remove unneeded init code, tidy whitespace
>
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