linux-toradex.git/lib/div64.c, branch v3.12-rc5

math64: New separate div64_u64_rem helper

2013-08-23T13:02:14+00:00

Commit f792685006274a850e6cc0ea9ade275ccdfc90bc ("math64: New
div64_u64_rem helper") implemented div64_u64 in terms of div64_u64_rem.
But div64_u64_rem was removed because it slowed down div64_u64 (and
there were no other users of div64_u64_rem).

Device Mapper's I/O statistics support has a need for div64_u64_rem;
reintroduce this helper as a separate method that doesn't slow down
div64_u64, especially on 32-bit systems.

Signed-off-by: Mike Snitzer 
Cc: Stanislaw Gruszka 
Cc: Ingo Molnar 
Cc: Frederic Weisbecker 
Cc: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

Revert "math64: New div64_u64_rem helper"

2013-04-30T17:13:05+00:00

This reverts commit f792685006274a850e6cc0ea9ade275ccdfc90bc.

The cputime scaling code was changed/fixed and does not need the
div64_u64_rem() primitive anymore. It has no other users, so let's
remove them.

Signed-off-by: Stanislaw Gruszka 
Cc: Frederic Weisbecker 
Cc: rostedt@goodmis.org
Cc: Linus Torvalds 
Cc: Dave Hansen 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1367314507-9728-4-git-send-email-sgruszka@redhat.com
Signed-off-by: Ingo Molnar

math64: New div64_u64_rem helper

2013-03-13T17:03:27+00:00

Provide an extended version of div64_u64() that
also returns the remainder of the division.

We are going to need this to refine the cputime
scaling code.

Signed-off-by: Frederic Weisbecker 
Cc: Stanislaw Gruszka 
Cc: Steven Rostedt 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Andrew Morton

lib: correct link to the original source for div64_u64

2012-06-28T09:51:39+00:00

Signed-off-by: Akinobu Mita 
Cc: Jiri Kosina 
Signed-off-by: Jiri Kosina

lib: reduce the use of module.h wherever possible

2012-03-07T20:04:04+00:00

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include.  Fix up any implicit
include dependencies that were being masked by module.h along
the way.

Signed-off-by: Paul Gortmaker

div64_u64(): improve precision on 32bit platforms

2010-10-26T23:52:19+00:00

The current implementation of div64_u64 for 32bit systems returns an
approximately correct result when the divisor exceeds 32bits.  Since doing
64bit division using 32bit hardware is a long since solved problem we just
use one of the existing proven methods.

Additionally, add a div64_s64 function to correctly handle doing signed
64bit division.

Addresses https://bugzilla.redhat.com/show_bug.cgi?id=616105

Signed-off-by: Brian Behlendorf 
Signed-off-by: Oleg Nesterov 
Cc: Ben Woodard 
Cc: Jeremy Fitzhardinge 
Cc: Mark Grondona 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

add an inlined version of iter_div_u64_rem

2008-06-12T08:47:58+00:00

iter_div_u64_rem is used in the x86-64 vdso, which cannot call other
kernel code.  For this case, provide the always_inlined version,
__iter_div_u64_rem.

Signed-off-by: Jeremy Fitzhardinge 
Signed-off-by: Ingo Molnar

common implementation of iterative div/mod

2008-06-12T08:47:56+00:00

We have a few instances of the open-coded iterative div/mod loop, used
when we don't expcet the dividend to be much bigger than the divisor.
Unfortunately modern gcc's have the tendency to strength "reduce" this
into a full mod operation, which isn't necessarily any faster, and
even if it were, doesn't exist if gcc implements it in libgcc.

The workaround is to put a dummy asm statement in the loop to prevent
gcc from performing the transformation.

This patch creates a single implementation of this loop, and uses it
to replace the open-coded versions I know about.

Signed-off-by: Jeremy Fitzhardinge 
Cc: Andrew Morton 
Cc: john stultz 
Cc: Segher Boessenkool 
Cc: Christian Kujau 
Cc: Robert Hancock 
Signed-off-by: Ingo Molnar

rename div64_64 to div64_u64

2008-05-01T15:03:58+00:00

Rename div64_64 to div64_u64 to make it consistent with the other divide
functions, so it clearly includes the type of the divide.  Move its definition
to math64.h as currently no architecture overrides the generic implementation.
 They can still override it of course, but the duplicated declarations are
avoided.

Signed-off-by: Roman Zippel 
Cc: Avi Kivity 
Cc: Russell King 
Cc: Geert Uytterhoeven 
Cc: Ralf Baechle 
Cc: David Howells 
Cc: Jeff Dike 
Cc: Ingo Molnar 
Cc: "David S. Miller" 
Cc: Patrick McHardy 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

introduce explicit signed/unsigned 64bit divide

2008-05-01T15:03:58+00:00

The current do_div doesn't explicitly say that it's unsigned and the signed
counterpart is missing, which is e.g.  needed when dealing with time values.

This introduces 64bit signed/unsigned divide functions which also attempts to
cleanup the somewhat awkward calling API, which often requires the use of
temporary variables for the dividend.  To avoid the need for temporary
variables everywhere for the remainder, each divide variant also provides a
version which doesn't return the remainder.

Each architecture can now provide optimized versions of these function,
otherwise generic fallback implementations will be used.

As an example I provided an alternative for the current x86 divide, which
avoids the asm casts and using an union allows gcc to generate better code.
It also avoids the upper divde in a few more cases, where the result is known
(i.e.  upper quotient is zero).

Signed-off-by: Roman Zippel 
Cc: john stultz 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds