Re: [PATCH 0/2] arm64: Introduce boot parameter to disable TLB flush instruction within the same inner shareable domain

[Jon Masters]

On 7/8/19 8:25 PM, Jon Masters wrote:
> On 7/2/19 10:45 PM, qi.fuli@xxxxxxxxxxx wrote:
> 
>> However, we found that with the increase of that the TLB flash was called,
>> the noise was also increasing. Here we understood that the cause of this 
>> issue is the implementation of Linux's TLB flush for arm64, especially use of 
>> TLBI-is instruction which is a broadcast to all processor core on the system. 
> 
> Are you saying that for a microbenchmark in which very large numbers of
> threads are created and destroyed rapidly there are a large number of
> associated tlb range flushes which always use broadcast TLBIs?
> 
> If that's the case, and the hardware doesn't do any ASID filtering and
> each TLBI results in a DVM to every PE, would it make sense to look at
> whether there are ways to improve batching/switch to an IPI approach
> rather than relying on broadcasts, as a more generic solution?

What I meant was a heuristic to do this automatically, rather than via a
command line.

Jon.