Re: Candidate Linux ABI for Intel AMX and hypothetical new related features

[Andy Lutomirski]

> On Apr 15, 2021, at 10:00 AM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> 
> On 4/15/21 9:24 AM, Andy Lutomirski wrote:
>> In the patches, *as submitted*, if you trip the XFD #NM *once* and you
>> are the only thread on the system to do so, you will eat the cost of a
>> WRMSR on every subsequent context switch.
> 
> I think you're saying: If a thread trips XFD #NM *once*, every switch to
> and from *that* thread will incur the WRMSR cost.

Indeed.  My sentence was missing a few words at the end.

> 
> The first time I read this, I thought you were saying that all threads
> would incur a WRMSR cost on every context switch.  If that's the case, I
> grossly misread the patches. :)