Re: [PATCH v3 1/3] arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error

From	Nicolai Stange <nicstange@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 1/3] arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error
Date	2016-07-13 16:40 +0200
Message-ID	<rUtuq-4iQ-11@gated-at.bofh.it> (permalink)
References	<rUs5k-3uO-3@gated-at.bofh.it> <rUs5k-3uO-1@gated-at.bofh.it> <rUsRH-3OH-13@gated-at.bofh.it> <rUsRH-3OH-21@gated-at.bofh.it>
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Paolo Bonzini <pbonzini@redhat.com> writes:

> On 13/07/2016 15:49, Peter Zijlstra wrote:
>> On Wed, Jul 13, 2016 at 03:03:42PM +0200, Nicolai Stange wrote:
>> 
>>>  		clockevents_config_and_register(levt,
>>> +						(u32)(((u64)tsc_khz * 1000) /
>>> +							TSC_DIVISOR),
>>>  						0xF, ~0UL);
>> 
>> div_u64() perhaps ?
>
> Or just squash together the two patches and do
>
> 	tsc_khz * (1000 / TSC_DIVISOR)
>
> because with TSC_DIVISOR equal to 2/4/8 there is no error from
> reassociating the operation.

Oh great, I didn't see this. Will resend.

Thanks,

Nicolai

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[PATCH v3 1/3] arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error Nicolai Stange <nicstange@gmail.com> - 2016-07-13 15:10 +0200
  Re: [PATCH v3 1/3] arch, x86, tsc deadline clockevent dev: reduce  frequency roundoff error Peter Zijlstra <peterz@infradead.org> - 2016-07-13 16:00 +0200
    Re: [PATCH v3 1/3] arch, x86, tsc deadline clockevent dev: reduce  frequency roundoff error Paolo Bonzini <pbonzini@redhat.com> - 2016-07-13 16:00 +0200
      Re: [PATCH v3 1/3] arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error Nicolai Stange <nicstange@gmail.com> - 2016-07-13 16:40 +0200

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