From: "Zengtao (B)" <prime.zeng@hisilicon.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>,
LKML <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: RE: [PATCH] cputime: Fix timeval-->cputime conversion
Date: Tue, 2 Feb 2016 02:57:40 +0000 [thread overview]
Message-ID: <678F3D1BB717D949B966B68EAEB446ED0A6B5D2A@SZXEMA509-MBX.china.huawei.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1602010942150.25254@nanos>
> -----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
>
prev parent reply other threads:[~2016-02-02 2:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 7:02 [PATCH] cputime: Fix timeval-->cputime conversion zengtao
2016-01-28 8:22 ` Thomas Gleixner
2016-01-28 11:52 ` Arnd Bergmann
2016-01-29 3:12 ` Zengtao (B)
2016-01-29 8:46 ` Arnd Bergmann
2016-01-30 2:31 ` Zengtao (B)
2016-02-01 3:51 ` Zengtao (B)
2016-02-01 8:43 ` Thomas Gleixner
2016-02-02 2:57 ` Zengtao (B) [this message]
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