linux-kernel - Re: [PATCH 2/5] powerpc: module_[32|64].c: replace swap function with built-in one

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Message-Id: <673731554232279@sas1-633109cb7707.qloud-c.yandex.net>
Date:   Tue, 02 Apr 2019 22:11:19 +0300
From:   Andrey Abramov <st5pub@...dex.ru>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] powerpc: module_[32|64].c: replace swap function with built-in one

01.04.2019, 13:11, "Michael Ellerman" <mpe@...erman.id.au>:
> This looks OK. It's a bit of a pity to replace the 8-byte-at-a-time copy
> with a byte-at-a-time copy, but I suspect it's insignificant compared to
> the overhead of calling the comparison and swap functions.
>
> And we could always add a generic 8-byte-at-a-time swap function if it's
> a bottleneck.

I am sorry, I forgot to quickly comment on your letter.
Now (after George Spelvin's patches) the generic swap is able
to use u64 or u32 if the alignment and size are divisible
by 4 or 8, so we lose nothing here.