Messages in this thread | | | From | "Zengtao (B)" <> | Subject | RE: [PATCH] cputime: Fix timeval-->cputime conversion | Date | Tue, 2 Feb 2016 02:57:40 +0000 |
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> -----Original Message----- > From: Thomas Gleixner [mailto:tglx@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 >
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