Re: [PATCH RESEND] fs: Move bh_cachep to the __read_mostly section

From: Chinmay V S
Date: Mon Jul 02 2012 - 14:24:36 EST


Hi Vlad,

I suppose we both are looking at opposite sides of the same coin.
While i am wary of the potential pitfalls,
you have focused on the benefits of using __read_mostly.

At this point i would like to send out a shout to everyone concerned to please
clarify the status of __read_mostly:

1. Is it being actively pursued? (systems that *will* clearly benefit from it)
2. Any actual results on real world use-cases? (w/ & w/o __read_mostly)
3. Is __read_mostly being accepted in non-architecture specific kernel code?
4. Is anyone working on a potential replacement for it?

regards
ChinmayVS


>I think your point is clear and has actually been nicely stated at
>thecodeartist.blogspot.com/2011/12/why-readmostly-does-not-work-as-it.htm
>(by u? :))

PS: Yes, the link i referred to *is* indeed my own article that i posted a few
months ago after my experiments with __read_mostly. I was initially excited when
i found this bit while digging through the code. But upon seeing that an entire
arch had disabled it, and then understanding why, i feel its usage needs to be
restricted to arch specific code and even then thoroughly tested too.
(then again, i may be wrong.)
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