Both VMX and SVM propagate virtual_tsc_khz in the same way, so this
patch removes the call-back set_tsc_khz() and replaces it with a common
function.
Signed-off-by: Haozhong Zhang <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
VMX and SVM calculate the TSC scaling ratio in a similar logic, so this
patch generalizes it to a common TSC scaling function.
Signed-off-by: Haozhong Zhang <[email protected]>
[Inline the multiplication and shift steps into mul_u64_u64_shr. Remove
BUG_ON. - Paolo]
Signed-off-by: Paolo Bonzini <[email protected]>
Commit f792685006 ("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 <[email protected]>
Cc: Stanislaw Gruszka <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Mikulas Patocka <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
There is div64_long() to handle the s64/long division, but no mocro do
u64/ul division. It is necessary in some scenarios, so add this
function.
[[email protected]: coding-style fixes]
Signed-off-by: Alex Shi <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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 <[email protected]>
Signed-off-by: Oleg Nesterov <[email protected]>
Cc: Ben Woodard <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
Cc: Mark Grondona <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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 <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
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 <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: john stultz <[email protected]>
Cc: Segher Boessenkool <[email protected]>
Cc: Christian Kujau <[email protected]>
Cc: Robert Hancock <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
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 <[email protected]>
Cc: john stultz <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Haozhong Zhang