Bug 93797

[    1.070360] clocksource: timekeeping watchdog: Marking clocksource 'tsc' as unstable because the skew is too large:
[    1.070361] clocksource:                       'hpet' wd_now: 53c870a wd_last: 4a8f15f mask: ffffffff
[    1.070362] clocksource:                       'tsc' cs_now: a6714a774 cs_last: a43566810 mask: ffffffffffffffff

is the first bad sign.

Created attachment 121165 [details] [review]
Fix system clock frequency

(In reply to Chris Wilson from comment #1)
> [    1.070360] clocksource: timekeeping watchdog: Marking clocksource 'tsc'
> as unstable because the skew is too large:
> [    1.070361] clocksource:                       'hpet' wd_now: 53c870a
> wd_last: 4a8f15f mask: ffffffff
> [    1.070362] clocksource:                       'tsc' cs_now: a6714a774
> cs_last: a43566810 mask: ffffffffffffffff
> 
> is the first bad sign.

Elio, please give a try to the attached patch, if it:
- gets rid of the above message
- gets rid of the slow-down

Assigned to Elio to check the patch.

The kernel with the patch seems to improve performance, but it is not gone 100%, our improvement is about a 50%, i will share the log as soon as possible.

Created attachment 121187 [details]
Dmesg log after patch

(In reply to Elio from comment #5)
> Created attachment 121187 [details]
> Dmesg log after patch

At least BogoMIPS looks sane now. Not sure what's the effect of this issue, I just noticed that I ran for a while without this fix and don't see any obvious slow-down.

Could you provide your BIOS info:
# dmidecode | grep -A3 "BIOS Information"

If it's not the latest working version, please try to upgrade.

APLK_IFWI_X64_R_2016_02_4_00

APLKRVPA.X64.0119.R10.160131622

(In reply to Elio from comment #7)
> APLK_IFWI_X64_R_2016_02_4_00

(In reply to Elio from comment #8)
> APLKRVPA.X64.0119.R10.160131622

Not sure about these BIOS versions. The latest official BIOS version is the following, please try to flash these:
IFWI: APLK_IFWI_X64_R_2015_52_4_00 (APLKRVPA.X64.0116.R20.1512211905)
KSC: 1.06

Please contact Sam Huston on where to get these, or if in doubt.

Sure, in the middle time in setting maxcpus in grub with 1 and it looks a lot better.

(In reply to Elio from comment #10)
> Sure, in the middle time in setting maxcpus in grub with 1 and it looks a
> lot better.

Ok, I can confirm this, I can see it on my system as well now. This started to happen when I upgraded to the BIOS I suggested to you in comment#9, so probably that won't solve your problem. Booting with maxcpus=1 gets rid of the issue for me too. I will try now different BIOS versions to see which one is the latest that works.

Meanwhile this isn't a graphics driver issue, I can see the problem even if I don't start the graphical interface, just by trying to type something on the text console. I notified already the core people (Mika Westerberg), he promised to take a look at this.

(In reply to Imre Deak from comment #11)
> (In reply to Elio from comment #10)
> > Sure, in the middle time in setting maxcpus in grub with 1 and it looks a
> > lot better.
> 
> Ok, I can confirm this, I can see it on my system as well now. This started
> to happen when I upgraded to the BIOS I suggested to you in comment#9, so
> probably that won't solve your problem. Booting with maxcpus=1 gets rid of
> the issue for me too. I will try now different BIOS versions to see which
> one is the latest that works.
> 
> Meanwhile this isn't a graphics driver issue, I can see the problem even if
> I don't start the graphical interface, just by trying to type something on
> the text console. I notified already the core people (Mika Westerberg), he
> promised to take a look at this.

One more thing I noticed that this is somehow related to GFX RC6 state. If we disable that via BIOS (Uncore/Render:C6 disable, GT PM: disable) or by booting with i915.enable_rc6=0 then we also don't have the problem. I assume entering RC6 would enable some deeper CPU/system level power state, which could cause this lag.

(In reply to Imre Deak from comment #12)
> (In reply to Imre Deak from comment #11)
> > (In reply to Elio from comment #10)
> > > Sure, in the middle time in setting maxcpus in grub with 1 and it looks a
> > > lot better.
> > 
> > Ok, I can confirm this, I can see it on my system as well now. This started
> > to happen when I upgraded to the BIOS I suggested to you in comment#9, so
> > probably that won't solve your problem. Booting with maxcpus=1 gets rid of
> > the issue for me too. I will try now different BIOS versions to see which
> > one is the latest that works.
> > 
> > Meanwhile this isn't a graphics driver issue, I can see the problem even if
> > I don't start the graphical interface, just by trying to type something on
> > the text console. I notified already the core people (Mika Westerberg), he
> > promised to take a look at this.
> 
> One more thing I noticed that this is somehow related to GFX RC6 state. If
> we disable that via BIOS (Uncore/Render:C6 disable, GT PM: disable) or by
> booting with i915.enable_rc6=0 then we also don't have the problem. I assume
> entering RC6 would enable some deeper CPU/system level power state, which
> could cause this lag.

Two other BIOS setup options under 'CPU Configuration'/'CPU Power Management' to get rid of the lag (either one alone gets rid of the lag while having the above RC6 and GT PM options enabled):
1. Max Core C State: 'Fused value'->'Core C6'
2. Max Package C State: 'S0ix default' -> 'C0'/'PC2'

(In reply to Imre Deak from comment #13)
> Two other BIOS setup options under 'CPU Configuration'/'CPU Power
> Management' to get rid of the lag (either one alone gets rid of the lag
> while having the above RC6 and GT PM options enabled):
> 1. Max Core C State: 'Fused value'->'Core C6'
> 2. Max Package C State: 'S0ix default' -> 'C0'/'PC2'

Err, the above correctly is 'S0ix default' -> 'C0'. Setting it to PC2 is not enough.

(In reply to Imre Deak from comment #14)
> (In reply to Imre Deak from comment #13)
> > Two other BIOS setup options under 'CPU Configuration'/'CPU Power
> > Management' to get rid of the lag (either one alone gets rid of the lag
> > while having the above RC6 and GT PM options enabled):
> > 1. Max Core C State: 'Fused value'->'Core C6'
> > 2. Max Package C State: 'S0ix default' -> 'C0'/'PC2'
> 
> Err, the above correctly is 'S0ix default' -> 'C0'. Setting it to PC2 is not
> enough.

Hi Imre Deak :

Can you teach me how to set up this two BIOS features in the grub 

1. Max Core C State: 'Fused value'->'Core C6'
2. Max Package C State: 'S0ix default' -> 'C0'


like in your previous comment , i mean something like this :
i915.enable_rc6=0

i would appreciate your help in this, because i can set up in the BIOS, but is most comfortable set it in grub menu, thanks in advanced

(In reply to Humberto Israel Perez Rodriguez from comment #15)
> (In reply to Imre Deak from comment #14)
> > (In reply to Imre Deak from comment #13)
> > > Two other BIOS setup options under 'CPU Configuration'/'CPU Power
> > > Management' to get rid of the lag (either one alone gets rid of the lag
> > > while having the above RC6 and GT PM options enabled):
> > > 1. Max Core C State: 'Fused value'->'Core C6'
> > > 2. Max Package C State: 'S0ix default' -> 'C0'/'PC2'
> > 
> > Err, the above correctly is 'S0ix default' -> 'C0'. Setting it to PC2 is not
> > enough.
> 
> Hi Imre Deak :
> 
> Can you teach me how to set up this two BIOS features in the grub 
> 
> 1. Max Core C State: 'Fused value'->'Core C6'
> 2. Max Package C State: 'S0ix default' -> 'C0'
> 
> like in your previous comment , i mean something like this :
> i915.enable_rc6=0
> 
> i would appreciate your help in this, because i can set up in the BIOS, but
> is most comfortable set it in grub menu, thanks in advanced

I don't know of any option to limit the package C state. There seems to be processor.max_cstate to limit the core C state, but for some reason I had to limit it to C2 as opposed to the C6 limit I set in BIOS. So removing the i915.enable_rc6=0 option and booting with processor.max_cstate=2 also gets rid of the problem.

*** This bug has been marked as a duplicate of bug 94706 ***

this issue does not occurs with bios 147.21 APL