Date: Fri, 28 Feb 2014 22:42:24 +1100 From: Peter Jeremy <peter@rulingia.com> To: arch@FreeBSD.org Subject: Re: small kernel kernel option... Message-ID: <20140228114224.GE2705@server.rulingia.com> In-Reply-To: <20140226214816.GB92037@funkthat.com> References: <20140226214816.GB92037@funkthat.com>
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--q9KOos5vDmpwPx9o Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2014-Feb-26 13:48:16 -0800, John-Mark Gurney <jmg@funkthat.com> wrote: >I'm about to commit a change to sha256 to speed it up, but the cost >of that speed up is an increase in code/data size from just under 1k >to almost 9k (as measured on amd64)... this increase is from unrolling >a loop.. Out of interest, how much of a speedup and what CPU/compiler combinations did you test your change on? I ask because several years ago, I tried about 7 different SHA-256 implementations (basically, all the C ones I could easily find in FreeBSD and ports I had installed, as well as one I tweaked myself) across a range of CPUs and compilers. I found that not only was there a very wide variation in speed between implementations but that the best on one CPU often ran quite poorly on another and unrolling loops didn't necessarily help. --=20 Peter Jeremy --q9KOos5vDmpwPx9o Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iKYEARECAGYFAlMQdiBfFIAAAAAALgAoaXNzdWVyLWZwckBub3RhdGlvbnMub3Bl bnBncC5maWZ0aGhvcnNlbWFuLm5ldDBCRjc3QTcyNTg5NEVCRTY0RjREN0VFRUZF OEE0N0JGRjAwRkI4ODcACgkQ/opHv/APuIfJAgCcCDPc8M7zXY+CXQP2RLcPgA2/ I+sAoIKZYCrb1xoKofOPwniloOR7yofx =WjFN -----END PGP SIGNATURE----- --q9KOos5vDmpwPx9o--
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