RE: [PATCH] x86/smpboot: Don't do mwait_play_dead() on AMD systems

2018-04-03 Thread Ghannam, Yazen
> -Original Message- > From: Ingo Molnar On Behalf Of Ingo Molnar > Sent: Tuesday, April 3, 2018 10:41 AM > To: Ghannam, Yazen > Cc: x...@kernel.org; linux-kernel@vger.kernel.org; b...@suse.de > Subject: Re: [PATCH] x86/smpboot: Don't do mwait_play_

Re: [PATCH] x86/smpboot: Don't do mwait_play_dead() on AMD systems

2018-04-03 Thread Ingo Molnar
* Ghannam, Yazen wrote: > > -Original Message- > > From: Ingo Molnar On Behalf Of Ingo Molnar > > Sent: Tuesday, April 3, 2018 7:04 AM > > To: Ghannam, Yazen > > Cc: x...@kernel.org; linux-kernel@vger.kernel.org; b...@suse.de > > Subjec

RE: [PATCH] x86/smpboot: Don't do mwait_play_dead() on AMD systems

2018-04-03 Thread Ghannam, Yazen
> -Original Message- > From: Ingo Molnar On Behalf Of Ingo Molnar > Sent: Tuesday, April 3, 2018 7:04 AM > To: Ghannam, Yazen > Cc: x...@kernel.org; linux-kernel@vger.kernel.org; b...@suse.de > Subject: Re: [PATCH] x86/smpboot: Don't do mwait_play_dead() on AMD &g

Re: [PATCH] x86/smpboot: Don't do mwait_play_dead() on AMD systems

2018-04-03 Thread Ingo Molnar
* Yazen Ghannam wrote: > From: Yazen Ghannam > > Recent AMD systems support using MWAIT for C1 state. However, MWAIT will > not allow deeper cstates than C1 on current systems. > > With play_dead() we expect the OS to use the deepest state available. > The deepest state available on AMD syste

[PATCH] x86/smpboot: Don't do mwait_play_dead() on AMD systems

2018-04-02 Thread Yazen Ghannam
From: Yazen Ghannam Recent AMD systems support using MWAIT for C1 state. However, MWAIT will not allow deeper cstates than C1 on current systems. With play_dead() we expect the OS to use the deepest state available. The deepest state available on AMD systems is reached through SystemIO or HALT.