Messages in this thread | | | Date | Thu, 3 Jan 2008 09:52:39 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] procfs: provide slub's /proc/slabinfo |
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* Matt Mackall <mpm@selenic.com> wrote:
> > Which means that SLOB could also trivially implement the same thing, > > with no new #ifdef'fery or other crud. > > Except SLOB's emulation of slabs is so thin, it doesn't have the > relevant information. We have a very small struct kmem_cache, which I > suppose could contain a counter. But we don't have anything like the > kmalloc slabs, so you'd only be getting half the picture anyway. The > output of slabtop would simply be misleading because there are no > underlying "slabs" in the first place.
i think SLOB/embedded is sufficiently special that a "no /proc/slabinfo" restriction is perfectly supportable. (for instance it's only selectable if CONFIG_EMBEDDED=y) If a SLOB user has any memory allocation problems it's worth going to the bigger allocators anyway, to get all the debugging goodies.
btw., do you think it would be worth/possible to have build mode for SLUB that is acceptably close to the memory efficiency of SLOB? (and hence work towards unifying all the 3 allocators into SLUB in essence)
right now we are far away from it - SLUB has an order of magnitude larger .o than SLOB, even on UP. I'm wondering why that is so - SLUB's data structures _are_ quite compact and could in theory be used in a SLOB-alike way. Perhaps one problem is that much of SLUB's debugging code is always built in?
Ingo
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