> -----Original Message----- > From: Thomas Gleixner [mailto:t...@linutronix.de] > Sent: Monday, February 01, 2016 4:43 PM > To: Zengtao (B) > Cc: Arnd Bergmann; LKML; Frederic Weisbecker > Subject: RE: [PATCH] cputime: Fix timeval-->cputime conversion > > On Mon, 1 Feb 2016, Zengtao (B) wrote: > > > Hi Arnd: > > I have got a new idea about the problem: > > In include/linux/time64.h > > #define NSEC_PER_SEC 1000000000L > > I think we should change it to > > #define NSEC_PER_SEC 1000000000LL > > > > My reason is : > > 1. when it is used in a multiplication, it will easily get overflow. > > 2. when it don't get overflow, the change has no side affect. > > That's not a good idea. NSEC_PER_SEC is used in lots of places with 32bit > storage. I really don't want to mop up all the fallout.
Yes, agree, a lot of places it has been used as 32bit value. Beyond that, I think it is more reasonable to use 64bit. > > Thanks, > > tglx >
