On 01/04/2016 08:15 PM, Haozhong Zhang wrote:
On 01/04/16 13:26, Boris Ostrovsky wrote:
On 12/30/2015 10:03 PM, Haozhong Zhang wrote:
This patch adds several functions to take multiplication, division and
shifting involving 64-bit integers. Those functions are derived from
Linux kernel and will be used by later patches to calculate scaling
ratio and scaled TSC.
Signed-off-by: Haozhong Zhang <haozhong.zh...@intel.com>
Reviewed-by: Boris Ostrovsky <boris.ostrov...@oracle.com>
(although I not sure why you decided to change Linux' code in mul64() below)
+ c = (u64)rl.l.high + rm.l.low + rn.l.low;
+ rl.l.high = c;
+ c >>= 32;
+ c = c + rm.l.high + rn.l.high + rh.l.low;
+ rh.l.low = c;
+ rh.l.high += (u32)(c >> 32);
I took these code from my KVM patches, but it seemed it was refactored
later and also inlined with mul_u64_u64_shr(). However, above code is
still equivalent to the current Linux code (if we take mul64() from
mul_u64_u64_shr() in Linux), so I think it should be fine. Or do you
want me to make them consistent with Linux code?
Yes, it is equivalent to what's in Linux. I don't think you need to do
anything, I was just curious why the two routines look slightly different.
-boris
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