linux-kernel - Re: THP backed thread stacks

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Message-ID: <278ec047-4c5d-ab71-de36-094dbed4067c@redhat.com>
Date:   Tue, 7 Mar 2023 11:10:23 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Rik van Riel <riel@...riel.com>
Subject: Re: THP backed thread stacks

On 07.03.23 00:57, Mike Kravetz wrote:
> One of our product teams recently experienced 'memory bloat' in their
> environment.  The application in this environment is the JVM which
> creates hundreds of threads.  Threads are ultimately created via
> pthread_create which also creates the thread stacks.  pthread attributes
> are modified so that stacks are 2MB in size.  It just so happens that
> due to allocation patterns, all their stacks are at 2MB boundaries.

Is this also related to a recent change, where we try to always align at 
PMD boundaries now, such that this gets more likely?

commit f35b5d7d676e59e401690b678cd3cfec5e785c23
Author: Rik van Riel <riel@...riel.com>
Date:   Tue Aug 9 14:24:57 2022 -0400

     mm: align larger anonymous mappings on THP boundaries


As a side note, I even heard of complains about memory bloat when 
switching from 4k -> 64k page size with many threads ...

-- 
Thanks,

David / dhildenb