On Sat, 24 Nov 2001, Andrea Arcangeli wrote:
> I don't care who has to do it, but who has to do it it has to do it in a
> very very very very slow path, and you want to handle it in iput fast
> path instead, cute?
Let's count. In the place where before -pre9 iput() had
return;
we have (2.4.15 + patch)
if (!sb || sb->s_flags & MS_ACTIVE)
return;
and on the fast path the first is false and second is true.
Price:
compare with zero
not taken branch
test (register + offset), <bit>
not taken branch
return
instead of
return
Compare with the stuff we had done just before that. Pollution of fast
path sucks, but here it _is_ noise.
I agree that variant in 2.4.15 is crap - hell, it's completely broken.
Please, grab the patch in question, apply to 2.4.15 and look at the
resulting code.
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This archive was generated by hypermail 2b29 : Fri Nov 30 2001 - 21:00:16 EST