linux-kernel - Re: [RFC PATCH 0/1] Buddy allocator like folio split

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7ec81ff8-5645-42a1-a048-c8700aff07fa@redhat.com>
Date: Fri, 18 Oct 2024 20:42:22 +0200
From: David Hildenbrand <david@...hat.com>
To: Zi Yan <ziy@...dia.com>, linux-mm@...ck.org,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: Ryan Roberts <ryan.roberts@....com>, Hugh Dickins <hughd@...gle.com>,
 "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
 Yang Shi <yang@...amperecomputing.com>, Miaohe Lin <linmiaohe@...wei.com>,
 Kefeng Wang <wangkefeng.wang@...wei.com>, Yu Zhao <yuzhao@...gle.com>,
 John Hubbard <jhubbard@...dia.com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 0/1] Buddy allocator like folio split

On 09.10.24 00:37, Zi Yan wrote:
> Hi all,

Hi!

> 
> Matthew and I have discussed about a different way of splitting large
> folios. Instead of split one folio uniformly into the same order smaller
> ones, doing buddy allocator like split can reduce the total number of
> resulting folios, the amount of memory needed for multi-index xarray
> split, and keep more large folios after a split. In addition, both
> Hugh[1] and Ryan[2] had similar suggestions before.
> 
> The patch is an initial implementation. It passes simple order-9 to
> lower order split tests for anonymous folios and pagecache folios.
> There are still a lot of TODOs to make it upstream. But I would like to gather
> feedbacks before that.

Interesting, but I don't see any actual users besides the debug/test 
interface wired up.

I assume ftruncate() / fallocate(PUNCH_HOLE) might be good use cases? 
For example, when punching 1M of a 2M folio, we can just leave a 1M 
folio in the pagecache.

Any other obvious users you have in mind?

-- 
Cheers,

David / dhildenb