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Re: [Xen-devel] [PATCH] Adjust time init sequence

>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 12.12.08 10:08 >>>
>On 12/12/2008 03:40, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>> A temp workaround is to move rdtscll(t->local_tsc_stamp) into
>> calibrate_tsc_bp, which gives a sane NOW() before percpu time
>> init. But then the purpose behind is ambiguous... why would we
>> want to count system time from this point? If we can't count
>> system time starting from power on, it looks clearer to tag system
>> time as 0 when initializing wc_sec/wc_nsec by do_settime.
>> Actually the starting point of xen system time is not that critical
>> since it's mostly used by relative progress. Then my previous
>> updated patch can be used? :-)
>How about rdtscll(t->local_tsc_stamp) at the top of init_xen_time(), and
>remove the one I added to early_time_init()? That would allow NOW() usage at
>least in init_xen_time(), and be later than the TSC reset.

Perhaps it should be considered to switch to the non-resetting
synchronization logic in x86-64 Linux up to 2.6.20 (according to the
comments there derived from ia64), or even the current version that
doesn't re-write the TSC at all?


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