2022-01-12 22:59:10

by Geert Uytterhoeven

[permalink] [raw]
Subject: Re: [PATCH crypto 1/2] lib/crypto: blake2s-generic: reduce code size on small systems

Hi Jason,

On Tue, Jan 11, 2022 at 2:49 PM Jason A. Donenfeld <[email protected]> wrote:
> Re-wind the loops entirely on kernels optimized for code size. This is
> really not good at all performance-wise. But on m68k, it shaves off 4k
> of code size, which is apparently important.

On arm32:

add/remove: 1/0 grow/shrink: 0/1 up/down: 160/-4212 (-4052)
Function old new delta
blake2s_sigma - 160 +160
blake2s_compress_generic 4872 660 -4212
Total: Before=9846148, After=9842096, chg -0.04%

On arm64:

add/remove: 1/2 grow/shrink: 0/1 up/down: 160/-4584 (-4424)
Function old new delta
blake2s_sigma - 160 +160
[email protected]_00007634_e8a0 8 - -8
[email protected]_0000423a_178c 8 - -8
blake2s_compress_generic 5088 520 -4568
Total: Before=32800278, After=32795854, chg -0.01%

> Signed-off-by: Jason A. Donenfeld <[email protected]>

For the size reduction:
Tested-by: Geert Uytterhoeven <[email protected]>

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds


2022-01-12 23:12:42

by Jason A. Donenfeld

[permalink] [raw]
Subject: Re: [PATCH crypto 1/2] lib/crypto: blake2s-generic: reduce code size on small systems

Hi Geert,

Thanks for testing this. However, I've *abandoned* this patch, due to
unacceptable performance hits, and figuring out that we can accomplish
basically the same thing without as large of a hit by modifying the
obsolete sha1 implementation.

Herbert - please do not apply this patch. Instead, later versions of
this patchset (e.g. v3 [1] and potentially later if it comes to that)
are what should be applied.

Jason

[1] https://lore.kernel.org/linux-crypto/[email protected]/