Experiencing some random hangs under heavy workload

[ltsdw]

I've been experiencing these hangs (where everything freezes for like 5 secs) when playing some games on wine that usually uses a lot of the CPU, sometimes when watching some videos.

To be sure that was cacule patch and nothing else I tested with the mainline arch kernel (no hangs). As I have some patches applied at my kernel I tried compiling it without the cacule patch (also no hangs). And then tried applying the cacule again and the hangs comes back.

I'm not quite sure. But I think that the commit that introduced it is the 06cb3974.

I didn't tried reverting the commit to test, only tested with these:

cacule-patch-with-hangs.txt - patch where hangs happens

cacule-without-hangs.txt - and without the hangs

But if needed I can try bisecting later to see exactly which commit causes it.

[ltsdw]

Also all the tunable configs are the default.

[raykzhao]

Hi @ltsdw

Based on #43, Have you tried to reduce the kernel.sched_cache_factor to a lower value e.g. 0? Also from my experience, you may try to set the kernel.sched_cacule_yield to 0 since it may cause freeze due to some I/O issues, see #35.

[ltsdw]

Hi there @raykzhao

Thank you for your suggestion I'll try.

[ltsdw]

sadly it didn't worked, tried:
kernel.sched_cache_factor=0
kernel.sched_cacule_yield=0

but the hangs still.

[hamadmarri]

kernel.sched_cache_factor=0

Could you please also set
kernel.sched_starve_factor=0

Is RDB enabled?

[ltsdw]

Could you please also set
kernel.sched_starve_factor=0

The hang still with kernel.sched_starve_factor=0

Is RDB enabled?

As I think it's enabled by default with the patch, I believe so.

[hamadmarri]

Could you please also set
kernel.sched_starve_factor=0

The hang still with kernel.sched_starve_factor=0

Is RDB enabled?

As I think it's enabled by default with the patch, I believe so.

Could you please try without RDB?

[ltsdw]

Could you please try without RDB?

As I don't think there is a runtime way to disable it, it's necessary recompile it, right?

[hamadmarri]

Could you please try without RDB?

As I don't think there is a runtime way to disable it, it's necessary recompile it, right?

Yes, you need to recompile. I think the version that was working for you was without RDB. Could you please attach the .config too?

Also provide all technical information and versions like kernel, wine, which game, and what settings.

Thanks

[ltsdw]

Yes, you need to recompile. I think the version that was working for you was without RDB. Could you please attach the .config too?

Also provide all technical information and versions like kernel, wine, which game, and what settings.

Thanks

Sure this one here was from my last compile on 5.13.8 config.txt.

CPU: i5 5200U
GPU: Intel(R) HD Graphics 5500 (using iris)
RAM: 8 GB
Mesa: 21.3.0 (commit c0fc745b78b)
Wine: 6.13 (with some patches from tkg)
Games that I tested with: NovaRO, GTA San Andreas, Path of Exile (this one I'll blame my gpu more than anything else), but it also happen out of nowhere when watching some videos too, or when I'm compiling something.

and when you say settings, you say which ones? the cacule's ones? if it's, it's all the default.

Now let me recompile it, will take some time.

[JohnyPeaN]

I have such lags in rdr2 (only) and setting kernel.sched_interactivity_factor=50 seems to be helping. It doesnt happen without RDB, but without RDB background load has stronger negative effects. I will test kernel.sched_starve_factor=0, too.

[ltsdw]

Yes, I can confirm, disabling the RDB did the trick, no more hangs, thank you @hamadmarri.

Also, not related to this issue but may I ask you, is there any straightforward tool to benchmark which of these tunable configs performs better?

[hamadmarri]

Yes, I can confirm, disabling the RDB did the trick, no more hangs, thank you @hamadmarri.

Also, not related to this issue but may I ask you, is there any straightforward tool to benchmark which of these tunable configs performs better?

Hi @ltsdw ,

Good to hear it's working fine now, however, I really would like to troubleshoot why RDB causes these freezes.

Regarding tunning, there is no specific way to test. I tried to make the defaults to work fine in general, but when you have any issue you can change them. You need to have a background on cpu scheduling so you can read about the every cacule sysctl and change them accordingly.

I would like to keep this issue open until we see why RDB performs bad with wine.

Thank you

[hamadmarri]

I suspect it is related to rcu calls and soft irq. I will post some fixes to try soon.

Thank you

[JohnyPeaN]

@hamadmarri, you might be onto somethinmg. This game does ~160k context switches, that might have something to do with it. But BMQ handles it, so its doable. I'm looking forward those fixes. Keep up the good work.