Cc: Andi Kleen <andi@...>, Christoph Lameter <clameter@...>, Peter Zijlstra <a.p.zijlstra@...>, Steven Rostedt <rostedt@...>, LKML <linux-kernel@...>, Andrew Morton <akpm@...>, Christoph Hellwig <hch@...>, Rafael J. Wysocki <rjw@...>
here's some silly statistics about allocator coverage on lkml, based on
configs reported to lkml in the past 4 months:
$ for N in SLAB SLUB SLOB; do printf "%s: " $N; grep ^CONFIG_$N=y linux-kernel | wc -l; done
SLAB: 70
SLUB: 77
SLOB: 4
so SLUB and SLAB is utilized about equally amongst people who reported
configs to lkml.
But people who use SLUB enabled it intentionally - and they are thus
much less likely to complain about this choice of them.
Reporting:
"I just enabled SLUB instead of SLAB, and hey guys, it does not have
SLABinfo"
has a foolish ring to it, doesnt it? I'd rather ask carefully, like this
person did:
http://kerneltrap.org/mailarchive/linux-kernel/2007/10/12/335765
This is one of the reasons why i think the whole SLAB->SLUB renaming was
bad - we should have done SLAB2 or SLAB^2 instead, so that people expect
_at least as good_ behavior (performance, features, etc.) from SLUB as
from SLAB. Instead of "something different".
anyway ... i think we still generally suck _alot_ at providing
near-transparent kernel upgrades to users. (kernel upgrades are still a
pain and risk, and often just due to poor developer choices on our
side.)
It's nowhere near as bad as the 2.4->2.6 transition was (in fact it
shouldnt even be mentioned in the same sentence), and it's getting
better gradually, but i think we should just by default be 10 times more
careful about these things - whenever it is borderline technically sane
to do so. We induce enough unintentional breakage of user-space, we
shouldnt compound it with intentional breakages. The kernel community
still has _a lot_ of user and distro trust to win back. So being seen as
over-cautious wont harm.
Ingo
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