From: "H. Peter Anvin" <hpa@zytor.com>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>, Tejun Heo <tj@kernel.org>,
Pekka Enbeerg <penberg@cs.helsinki.fi>,
linux-kernel@vger.kernel.org,
Eric Dumazet <eric.dumazet@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: x86: A fast way to check capabilities of the current cpu
Date: Wed, 15 Dec 2010 13:39:12 -0800 [thread overview]
Message-ID: <4D093580.9000303@zytor.com> (raw)
In-Reply-To: <AANLkTimhdmWGhxW9qnFWYxiVDManH4XG4RqTLJb_Fdbk@mail.gmail.com>
On 12/15/2010 01:30 PM, Miguel Ojeda wrote:
>
> In this case it this_cpu_*_test_bit() return an int, but they act as a
> bool and are used in if()s; where is the catch?
>
If they aren't, and are stored in a variable for whatever reason, then
the || form will generate additional instructions to booleanize the
value for no good reason.
-hpa
next prev parent reply other threads:[~2010-12-15 21:40 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-15 20:07 x86: A fast way to check capabilities of the current cpu Christoph Lameter
2010-12-15 20:11 ` x86: Avoid passing struct cpuinfo pointer to mce_available Christoph Lameter
2010-12-15 20:56 ` x86: A fast way to check capabilities of the current cpu Andrew Morton
2010-12-15 21:03 ` H. Peter Anvin
2010-12-15 21:30 ` Miguel Ojeda
2010-12-15 21:39 ` H. Peter Anvin [this message]
2010-12-15 21:48 ` Miguel Ojeda
2010-12-16 6:25 ` Miles Bader
2010-12-16 10:17 ` Miguel Ojeda
2010-12-16 10:29 ` Miles Bader
2010-12-16 15:38 ` H. Peter Anvin
2010-12-17 4:26 ` Miles Bader
2011-01-21 17:11 ` Tejun Heo
2011-01-21 17:21 ` Christoph Lameter
2011-01-21 17:28 ` Tejun Heo
2011-01-21 17:46 ` Christoph Lameter
2011-01-21 17:48 ` Tejun Heo
2011-01-21 17:57 ` Christoph Lameter
2011-01-21 18:12 ` Tejun Heo
2011-01-21 18:20 ` Christoph Lameter
2011-01-21 22:32 ` H. Peter Anvin
2011-01-24 17:05 ` Christoph Lameter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4D093580.9000303@zytor.com \
--to=hpa@zytor.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=eric.dumazet@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=miguel.ojeda.sandonis@gmail.com \
--cc=penberg@cs.helsinki.fi \
--cc=tj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.