Re: Regression, host crash with 4.5rc1

[Steve Freitas <sflist@ihonk.com>]

On 11/25/2014 03:00 AM, Jan Beulich wrote:
> Okay, so it's not really the mwait-idle driver causing the regression,
> but it is C-state related. Hence we're now down to seeing whether all
> or just the deeper C states are affected, i.e. I now need to ask you
> to play with "max_cstate=". For that you'll have to remember that the
> option's effect differs between the ACPI and the MWAIT idle drivers.
> In the spirit of bisection I'd suggest using "max_cstate=2" first no
> matter which of the two scenarios you pick. If that still hangs,
> "max_cstate=1" obviously is the only other thing to try. Should that
> not hang (and you left out "mwait-idle=0"), trying "max_cstate=3"
> in that same scenario would be the other case to check.
>
> No need for 'd' and 'a' output for the time being, but 'c' output would
> be much appreciated for all cases where you observe hangs.
>

Okay, working through that now. I tried max_cstate=2 and got no hangs, 
whether with or without mwait-idle=0. However, I was puzzled by this:

(XEN) 'c' pressed -> printing ACPI Cx structures
(XEN) ==cpu0==
(XEN) active state:             C0
(XEN) max_cstate:               C2
(XEN) states:
(XEN)     C1:   type[C1] latency[003] usage[12219860] method[  FFH] 
duration[1190961948551]
(XEN)     C2:   type[C1] latency[010] usage[10205554] method[  FFH] 
duration[2015393965907]
(XEN)     C3:   type[C2] latency[020] usage[50926286] method[  FFH] 
duration[30527997858148]
(XEN)    *C0:   usage[73351700] duration[9974627547595]
(XEN) max=0 pwr=0 urg=0 nxt=0
(XEN) PC2[0] PC3[8589642315848] PC6[0] PC7[0]
(XEN) CC3[28794734145697] CC6[0] CC7[0]
(XEN) ==cpu1==
(XEN) active state:             C3
(XEN) max_cstate:               C2
(XEN) states:
(XEN)     C1:   type[C1] latency[003] usage[10699950] method[  FFH] 
duration[1141422044112]
(XEN)     C2:   type[C1] latency[010] usage[06382904] method[  FFH] 
duration[1329739264322]
(XEN)    *C3:   type[C2] latency[020] usage[44630764] method[  FFH] 
duration[31676618425954]
(XEN)     C0:   usage[61713618] duration[9561201640320]
(XEN) max=0 pwr=0 urg=0 nxt=0
(XEN) PC2[0] PC3[8589642315848] PC6[0] PC7[0]
(XEN) CC3[30066495105056] CC6[0] CC7[0]
(XEN) ==cpu2==
(XEN) active state:             C3
(XEN) max_cstate:               C2
(XEN) states:
(XEN)     C1:   type[C1] latency[003] usage[10829791] method[  FFH] 
duration[1145244102917]
(XEN)     C2:   type[C1] latency[010] usage[06392468] method[  FFH] 
duration[1330830147023]
(XEN)    *C3:   type[C2] latency[020] usage[44705668] method[  FFH] 
duration[31741190985486]
(XEN)     C0:   usage[61927927] duration[9491716216846]
(XEN) max=0 pwr=0 urg=0 nxt=0
(XEN) PC2[0] PC3[8589642315848] PC6[0] PC7[0]
(XEN) CC3[30117696095715] CC6[0] CC7[0]
(XEN) ==cpu3==
(XEN) active state:             C3
(XEN) max_cstate:               C2
(XEN) states:
(XEN)     C1:   type[C1] latency[003] usage[10692336] method[  FFH] 
duration[1144876437514]
(XEN)     C2:   type[C1] latency[010] usage[06394051] method[  FFH] 
duration[1333961503379]
(XEN)    *C3:   type[C2] latency[020] usage[44744178] method[  FFH] 
duration[31803488799434]
(XEN)     C0:   usage[61830565] duration[9426654792908]
(XEN) max=0 pwr=0 urg=0 nxt=0
(XEN) PC2[0] PC3[8589642315848] PC6[0] PC7[0]
(XEN) CC3[30191557548300] CC6[0] CC7[0]
(XEN) ==cpu4==
(XEN) active state:             C3
(XEN) max_cstate:               C2
(XEN) states:
(XEN)     C1:   type[C1] latency[003] usage[10746634] method[  FFH] 
duration[1144044534459]
(XEN)     C2:   type[C1] latency[010] usage[06444054] method[  FFH] 
duration[1340637424913]
(XEN)    *C3:   type[C2] latency[020] usage[44690901] method[  FFH] 
duration[31663207165902]
(XEN)     C0:   usage[61881589] duration[9561092487876]
(XEN) max=0 pwr=0 urg=0 nxt=0
(XEN) PC2[0] PC3[8589642315848] PC6[0] PC7[0]
(XEN) CC3[30049235012919] CC6[0] CC7[0]
(XEN) ==cpu5==
(XEN) active state:             C3
(XEN) max_cstate:               C2
(XEN) states:
(XEN)     C1:   type[C1] latency[003] usage[10694684] method[  FFH] 
duration[1140625901110]
(XEN)     C2:   type[C1] latency[010] usage[06461563] method[  FFH] 
duration[1342115502967]
(XEN)    *C3:   type[C2] latency[020] usage[44834522] method[  FFH] 
duration[31719560664023]
(XEN)     C0:   usage[61990769] duration[9506679619986]
(XEN) max=0 pwr=0 urg=0 nxt=0
(XEN) PC2[0] PC3[8589642315848] PC6[0] PC7[0]

Why would some of the cores be in C3 even though they list max_cstate as C2?

Steve