Re: [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushesto use function calls [POST 2]

[Jeremy Fitzhardinge]

Andi Kleen wrote:
>> Don't pay attention to that number.  It's only the extra latency of a HT
>> context->HT context function call + tlb flush.  Which means 1) the tlb
>> is shared anyway, so the extra flush is redundant, 2) they're not really
>> concurrent, 3) it's going down the single-cpu call, rather than the
>> multi-cpu one, 4) it's only measuring the latency for a particular tlb
>> flush, and doesn't take into account any throughput improvements the
>> extra queueing may add.
>>     
>
> A lot of flushes are synchronous. See the rest of my email that
> you snipped.

Yep, sure, but I just wanted to be clear that the 35% number is almost
useless in isolation, and the first step is to do proper measurements.

    J
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/