Re: [LAU] Major CPU bugs - Was: Christmas present for self.

From: Robin Gareus <robin@email-addr-hidden>
Date: Thu Jan 04 2018 - 23:17:03 EET

On 01/04/2018 10:09 PM, Rob wrote:
> On 04/01/18 19:56, Paul Davis wrote:
>>
>> On Thu, Jan 4, 2018 at 2:43 PM, Robin Gareus <robin@gareus.org
>> <mailto:robin@gareus.org>> wrote:
>>
>>
>>     Depends on your DAW. In Ardour's case there is no context-switch. All
>>     tracks, Busses and FX run in the same process. So there won't be any
>>     direct effect.
>>
>>     Low-latency I/O however (soundcard) will see additional overhead, as
>>     will JACK with multiple clients (one context switch per client).
>>
>>
>> ​is this correct? my impression is that KPTI makes user->kernel and
>> kernel->user switches more expensive th​a they used to be, but does
>> not change the cost of a context switch that stays in the same ring mode.
>> ​
>> so, basically, system calls cost more; context switches stay at about
>> the same cost.
>
> https://lwn.net/Articles/741878/ - top-most page table is duplicated and
> stripped of kernel pages; duplicate is active when running userspace.
>

Thanks for the heads up. I stand corrected.

_______________________________________________
Linux-audio-user mailing list
Linux-audio-user@lists.linuxaudio.org
https://lists.linuxaudio.org/listinfo/linux-audio-user
Received on Fri Jan 5 00:15:02 2018

This archive was generated by hypermail 2.1.8 : Fri Jan 05 2018 - 00:15:02 EET