Messages in this thread | | | From | John Stultz <> | Date | Wed, 16 Nov 2016 12:31:05 -0800 | Subject | Re: [PATCH v2] tile: avoid using clocksource_cyc2ns with absolute cycle count |
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On Wed, Nov 16, 2016 at 12:29 PM, John Stultz <john.stultz@linaro.org> wrote: > On Wed, Nov 16, 2016 at 12:16 PM, Chris Metcalf <cmetcalf@mellanox.com> wrote: >> Change 4cecf6d401a0 results in essentially identical code for x86 as >> this proposed change does for tile. In fact a follow-on change by >> Salman introduced mult_frac() and switched to using it, so it was >> identical at that point. >> >> PeterZ (cc'ed) then improved it to use __int128 math via >> mul_u64_u32_shr(), but that doesn't help tile; we only do one multiply >> instead of two, but the multiply is handled by an out-of-line call to >> __multi3, and the sched_clock() function ends up about 2.5x slower as >> a result. >> >> Thanks for thinking about this! > > Heh. Thanks for the history lesson and apologies for my forgetfulness. :)
Oh.. and some of these details might be useful to have in the commit message!
thanks -john
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