From: Jeffrey Walton <noloader@gmail.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Denker <jsd@av8n.com>, "Theodore Ts'o" <tytso@mit.edu>,
linux-kernel@vger.kernel.org,
Stephan Mueller <smueller@chronox.de>,
Herbert Xu <herbert@gondor.apana.org.au>,
Andi Kleen <andi@firstfloor.org>,
Sandy Harris <sandyinchina@gmail.com>,
cryptography@lakedaemon.net, linux-crypto@vger.kernel.org
Subject: Re: better patch for linux/bitops.h
Date: Wed, 4 May 2016 23:30:24 -0400 [thread overview]
Message-ID: <CAH8yC8mbW5yTwbKN7_RMNVnTiKmtP0u3_2+tKV=-L4BZ6miGVw@mail.gmail.com> (raw)
In-Reply-To: <0015E1DE-DFF9-4CCE-805E-7AC286021BED@zytor.com>
>>> So you are actually saying outright that we should sacrifice *actual*
>>portability in favor of *theoretical* portability? What kind of
>>twilight zone did we just step into?!
>>
>>I'm not sure what you mean. It will be well defined on all platforms.
>>Clang may not recognize the pattern, which means they could run
>>slower. GCC and ICC will be fine.
>>
>>Slower but correct code is what you have to live with until the Clang
>>dev's fix their compiler.
>>
>>Its kind of like what Dr. Jon Bentley said: "If it doesn't have to be
>>correct, I can make it as fast as you'd like it to be".
>
> The current code works on all compilers we care about. The code you propose does not; it doesn't work on anything but very recent versions of our flagship target compiler, and pretty your own admission might even cause security hazards in the kernel if compiled on clang.
I'm not sure how you're arriving at the conclusion the code does not work.
> That qualifies as insane in my book.
OK, thanks.
I see the kernel is providing IPSec, SSL/TLS, etc. You can make
SSL/TLS run faster by using aNULL and eNULL.
Jeff
next prev parent reply other threads:[~2016-05-05 3:30 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-02 6:26 [RFC PATCH 0/3] random: replace urandom pool with a CRNG Theodore Ts'o
2016-05-02 6:26 ` [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG Theodore Ts'o
2016-05-03 8:50 ` Stephan Mueller
2016-05-04 16:54 ` Jeffrey Walton
2016-05-04 17:30 ` tytso
2016-05-04 17:52 ` H. Peter Anvin
2016-05-03 9:36 ` Stephan Mueller
2016-05-04 6:24 ` Stephan Mueller
2016-05-04 14:40 ` Jeffrey Walton
2016-05-04 17:49 ` tytso
2016-05-04 18:22 ` Jeffrey Walton
2016-05-04 18:29 ` H. Peter Anvin
2016-05-04 19:07 ` tytso
2016-05-04 20:53 ` H. Peter Anvin
2016-05-04 21:42 ` John Denker
2016-05-04 21:52 ` better patch for linux/bitops.h John Denker
2016-05-05 1:35 ` Jeffrey Walton
2016-05-05 2:41 ` H. Peter Anvin
2016-05-05 2:54 ` Jeffrey Walton
2016-05-05 3:08 ` H. Peter Anvin
2016-05-05 3:30 ` Jeffrey Walton [this message]
2016-05-05 3:50 ` Theodore Ts'o
2016-05-05 4:03 ` Jeffrey Walton
2016-05-05 6:35 ` H. Peter Anvin
2016-05-05 16:15 ` UB in general ... and linux/bitops.h in particular John Denker
2016-05-05 17:32 ` Andi Kleen
2016-05-06 2:25 ` Jeffrey Walton
2016-05-05 21:34 ` better patch for linux/bitops.h Sandy Harris
2016-05-05 22:18 ` tytso
2016-05-05 22:22 ` H. Peter Anvin
2016-05-05 22:38 ` H. Peter Anvin
2016-05-06 0:13 ` H. Peter Anvin
2016-05-04 21:56 ` [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG H. Peter Anvin
2016-05-04 22:06 ` linux/bitops.h John Denker
2016-05-04 23:06 ` linux/bitops.h Andi Kleen
2016-05-05 0:13 ` linux/bitops.h John Denker
2016-05-05 1:20 ` linux/bitops.h Jeffrey Walton
2016-05-05 1:27 ` linux/bitops.h H. Peter Anvin
2016-05-05 0:30 ` linux/bitops.h H. Peter Anvin
2016-05-05 0:48 ` linux/bitops.h Linus Torvalds
2016-05-06 20:08 ` linux/bitops.h Sasha Levin
2016-05-06 20:07 ` linux/bitops.h Sasha Levin
2016-05-06 20:25 ` linux/bitops.h H. Peter Anvin
2016-05-06 20:30 ` linux/bitops.h H. Peter Anvin
2016-05-02 6:26 ` [PATCH 2/3] random: make /dev/urandom scalable for silly userspace programs Theodore Ts'o
2016-05-02 7:00 ` Stephan Mueller
2016-05-02 12:50 ` Theodore Ts'o
2016-05-02 13:48 ` Theodore Ts'o
2016-05-02 13:53 ` Stephan Mueller
2016-05-02 6:26 ` [PATCH 3/3] random: add interrupt callback to VMBus IRQ handler Theodore Ts'o
2016-05-02 9:00 ` Jeffrey Walton
2016-05-02 9:14 ` Stephan Mueller
2016-05-02 12:56 ` Theodore Ts'o
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