> On Apr 30, 2021, at 15:53, Stuart Henderson <s...@spacehopper.org> wrote:
> 
> On 2021/04/05 09:34, Scott Cheloha wrote:
>>>> On Apr 5, 2021, at 09:07, Stuart Henderson <s...@spacehopper.org> wrote:
>>> I've attached r620-E5_2630v2-2p6c2t.tgz, from Dell PE R620 with E5-2630v2.
>>> This is a machine which has "disabling user TSC (skew=XXX)" reported for
>>> some cores:
>>> Nov  5 16:08:34 pweb /bsd: cpu11: disabling user TSC (skew=-107)
>>> Nov  5 16:08:34 pweb /bsd: cpu13: disabling user TSC (skew=-101)
>> This is probably NUMA latency when synchronizing between packages.
> 
> Interesting, just updated a dual socket R610 (Intel(R) Xeon(R) CPU L5520
> @ 2.27GHz, 2394.39 MHz, 06-1a-05, smt 0/1, core 0-3, package 0/1) to 6.9
> and remembered about this. In that case there's no "disabling user TSC".
> 
> Production server so not a good one for running debug kernels etc..but
> thought it was worth drafting a quick mail to mention that it's not all
> NUMA machines.

This is helpful, but skew numbers would be
even more helpful.

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