Re: CVS commit: src/sys/arch/x86/x86

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

Hi,

Hmm, but TSC drift is still observed on recent (high clock) CPUs.
I will have researched and fix later.

On 2020/04/03 12:05, Kengo NAKAHARA wrote:
> Module Name:	src
> Committed By:	knakahara
> Date:		Fri Apr  3 03:05:39 UTC 2020
>
> Modified Files:
> 	src/sys/arch/x86/x86: tsc.c
>
> Log Message:
> Fix TSC drift is observed almost every time wrongly.
>
> Ths "TSC drift" in tsc_tc_init() means the cpu_cc_skew delta between
> first measurement (in cpu_start_secondary) and second measurement
> (in cpu_boot_secondary), that is, the TSC drift is expected to be
> almost zero.  However, the second measument in current implementation
> is added extra cpu_cc_skew accidentally, so current delta value means
> almost cpu_cc_skew wrongly.
>
> tsc_sync_bp and tsc_sync_ap should use rdtsc() to get raw values.
>
> Advised by nonaka@n.o, thanks.
>
>
> To generate a diff of this commit:
> cvs rdiff -u -r1.38 -r1.39 src/sys/arch/x86/x86/tsc.c
>
> Please note that diffs are not public domain; they are subject to the
> copyright notices on the relevant files.

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Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>