Messages in this thread | | | From | John Stultz <> | Date | Wed, 16 Nov 2016 12:00:56 -0800 | Subject | Re: [PATCH] clocksource_cyc2ns: avoid overflowing 64 bits |
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On Wed, Nov 16, 2016 at 11:56 AM, Chris Metcalf <cmetcalf@mellanox.com> wrote: > On 11/16/2016 2:45 PM, John Stultz wrote: >> >> On Wed, Nov 16, 2016 at 11:30 AM, Chris Metcalf <cmetcalf@mellanox.com> >> wrote: >>> >>> diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h >>> index 08398182f56e..5444429884b8 100644 >>> --- a/include/linux/clocksource.h >>> +++ b/include/linux/clocksource.h >>> @@ -171,6 +171,10 @@ static inline u32 clocksource_hz2mult(u32 hz, u32 >>> shift_constant) >>> * >>> * Converts cycles to nanoseconds, using the given mult and shift. >>> * >>> + * The code is optimized for performance and not intended to work >>> + * with absolute clocksource cycles, as it will easily overflow, >>> + * but just intended for relative (delta) clocksource cycles. >>> + * >>> * XXX - This could use some mult_lxl_ll() asm optimization >> >> Just as a heads up, it seems your working against an older kernel, as >> this didn't apply. Its simple enough to fix up, so I'll do so, but in >> the future, please submit patches against something close to Linus >> HEAD. > > > Oops, sorry; it wasn't version skew (I'm at v4.9-rc4) but whitespace damage. > I assumed if I just pasted the patch into Thunderbird it would work, since > it had > no tabs. But bizarrely, if I look at the patch in the mailer, it shows a > two-space > prefix, but when I save the email to a file, it has a three-space prefix. > WTF?
Yea. Not many mailers can be trusted with sending patches. I'd recommend git-send-email. :)
thanks -john
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