linux-kernel - [PATCH] x86/mce: Dynamically size space for machine check records

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Message-ID: <f17da20f-4379-4dc6-b988-cb3a07f4aa6f@amd.com>
Date: Thu, 29 Feb 2024 12:28:45 -0600
From: "Naik, Avadhut" <avadnaik@....com>
To: Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>
Cc: "Mehta, Sohil" <sohil.mehta@...el.com>, "x86@...nel.org"
 <x86@...nel.org>, "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "yazen.ghannam@....com" <yazen.ghannam@....com>,
 Avadhut Naik <avadhut.naik@....com>
Subject: [PATCH] x86/mce: Dynamically size space for machine check records



On 2/29/2024 11:47, Tony Luck wrote:
> On Thu, Feb 29, 2024 at 09:39:51AM +0100, Borislav Petkov wrote:
>> On Thu, Feb 29, 2024 at 12:42:38AM -0600, Naik, Avadhut wrote:
>>> Somewhat confused here. Weren't we also exploring ways to avoid
>>> duplicate records from being added to the genpool? Has something
>>> changed in that regard?
>>
>> You can always send patches proposing how *you* think this duplicate
>> elimination should look like and we can talk. :)
>>
>> I don't think anyone would mind it if done properly but first you'd need
>> a real-life use case. As in, do we log sooo many duplicates such that
>> we'd want to dedup?
> 
> There are definitly cases where dedup will not help. If a row fails in a
> DIMM there will be a flood of correctable errors with different addresses
> (depending on number of channels in the interleave schema for a system
> this may be dozens or hundreds of distinct addresses).
> 
> Same for other failures in structures like column and rank.
> 

Wouldn't having dedup actually increase the time we spend #MC context?
Comparing the new MCE record against each existing record in the
genpool.

AFAIK, MCEs cannot be nested. Correct me if I am wrong here.

In a flood situation, like the one described above, that is exactly
what may happen: An MCE coming in while the dedup mechanism is
underway (in #MC context).

-- 
Thanks,
Avadhut Naik