linux-kernel - Re: commit 7ffb791423c7 breaks steam game

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Message-ID: <c5e5b3a7-e8ab-42c8-a33c-ce2c0dd21344@nvidia.com>
Date: Sat, 22 Mar 2025 13:06:29 +1100
From: Balbir Singh <balbirs@...dia.com>
To: Bert Karwatzki <spasswolf@....de>, Alex Deucher <alexdeucher@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>, Kees Cook <kees@...nel.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Peter Zijlstra <peterz@...radead.org>, Andy Lutomirski <luto@...nel.org>,
 linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org
Subject: Re: commit 7ffb791423c7 breaks steam game

On 3/21/25 23:26, Bert Karwatzki wrote:
>>>
>>
>> I am not an expert in amdgpu or gtt_mgr, but I wonder if some of the deletes are coming
>> from forceful eviction  of memory during allocation?
>>
>> Have you filed a bug report for the nokaslr case?
>>
>> Balbir Singh
> 
> I did some more monitoring and in the BAD case ttm_global_swapout() is called
> 585 times leading to 54495 calls to ttm_bo_swapout_cb() while in the GOOD both
> function are called 0 times.
> 

Could you please check if under /sys/kernel/debug

You can find a ttm directory under that hierarchy and a ttm_shrink file? Is anything
writing to the file (like the game?)

With nokaslr, do you see a change in the game characteristics, like more simulated
objects (an increase in fleet size, simulated objects)?

It might be interesting to debug the ttm_pages_limit to see if that changes when
nokaslr is enabled as well

Thanks!
Balbir