linux-kernel - Re: [PATCH v3 0/4] mm/folio_zero

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Message-ID: <e65acb10-3f33-4f41-bf25-7fa4028dd693@amd.com>
Date: Wed, 23 Apr 2025 14:48:50 +0530
From: Raghavendra K T <raghavendra.kt@....com>
To: Ankur Arora <ankur.a.arora@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
 torvalds@...ux-foundation.org, akpm@...ux-foundation.org, bp@...en8.de,
 dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
 luto@...nel.org, peterz@...radead.org, paulmck@...nel.org,
 rostedt@...dmis.org, tglx@...utronix.de, willy@...radead.org,
 jon.grimm@....com, bharata@....com, boris.ostrovsky@...cle.com,
 konrad.wilk@...cle.com
Subject: Re: [PATCH v3 0/4] mm/folio_zero_user: add multi-page clearing

On 4/23/2025 1:42 PM, Raghavendra K T wrote:
[...]

>> Also, any idea why the huge delta in the mm/folio_zero_user 2MB, 1GB
>> cases? Both of these are doing 4k page at a time, so the huge delta
>> is a little head scratching.
>>
>> There's a gap on Milan as well but it is much smaller.
>>
> 

Sorry forgot to add perhaps even more valid/important data point

> Need to think/analyze further, but from perf stat I see
> glaring difference in:
>              2M        1G
> pagefaults        32,906        202
> iTLB-load-misses    44,490        156

dTLB-loads		1,000,169	38,134
dTLB-load-misses	402,641		33,992

- Raghu