From: Ben Woodard <woodard@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
"Behlendorf, Brian D." <behlendorf1@llnl.gov>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Mark Grondona <mgrondona@llnl.gov>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] trivial, document that div64_u64() is not precise on 32bit platforms
Date: Tue, 03 Aug 2010 19:12:41 -0500 [thread overview]
Message-ID: <1280880761.10330.5.camel@snog.zork.net> (raw)
In-Reply-To: <20100803152812.210439dc.akpm@linux-foundation.org>
Andrew,
On Tue, 2010-08-03 at 15:28 -0700, Andrew Morton wrote:
> Well that was a bit lazy of us - I wonder how hard it is to fix.
>
> At present people will test their code on 64-bit only to find out
> later
> that it doesn't work correctly on 32-bit. Bad. Perhaps we should
> similarly break the 64-bit version :)
I just talked to Brian. He's got an implementation that does the
division correctly. He's going to clean it up and send you a patch so
that it will work without losing precision on both 32b and 64b. It is
based upon public domain code from http://www.hackersdelight.org and
has been proven to be correct in all cases.
-ben
next prev parent reply other threads:[~2010-08-04 0:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-02 16:09 Oleg Nesterov
2010-08-03 22:28 ` Andrew Morton
2010-08-04 0:12 ` Ben Woodard [this message]
2010-08-09 16:30 ` [PATCH] Make div64_u64() " Brian Behlendorf
2010-09-17 0:00 ` Oleg Nesterov
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