Date: Sat, 16 Sep 2017 07:54:47 +0100 From: Ed Schouten <ed@nuxi.nl> To: John Baldwin <jhb@freebsd.org> Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: UMA and zone alignment Message-ID: <CABh_MKnyDp-FjN38cmXCUq9SHLBdcQbTrekvjwU948=oWE70RA@mail.gmail.com> In-Reply-To: <10066620.9raPCKhsf8@ralph.baldwin.cx> References: <10066620.9raPCKhsf8@ralph.baldwin.cx>
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2017-09-16 0:38 GMT+01:00 John Baldwin <jhb@freebsd.org>:
> I think I'd like to add UMA_ALIGNOF() and encourage UMA zones to use
> UMA_ALIGNOF(type) instead of UMA_ALIGN_PTR, etc. going forward. This would
> mean UMA would then honor 'struct foo { ... } __aligned(XX)', etc. What do
> you all think?
Awesome!
Random remark: it looks like uma_zcreate() already takes the size of
the objects to allocate without any wrapping; it's just sizeof(...).
Wouldn't we be able to do this for alignment as well?
More specifically, if all of the UMA_ALIGN_* definitions were
incremented by one and uma_zcreate() decrements it, we could eliminate
the UMA_ALIGNOF() macro entirely and simply use _Alignof() at the call
site directly.
If people don't like _Alignof()'s spelling, we could always consider
making something like <stdalign.h> available in kernel space.
--
Ed Schouten <ed@nuxi.nl>
Nuxi, 's-Hertogenbosch, the Netherlands
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