linux-kernel - Re: [RFC PATCH v1 0/4] hugetlb: parallelize hugetlb page allocation on boot

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: <9d5de524-28ee-4d71-9493-f77967ea213c@redhat.com>
Date:   Fri, 24 Nov 2023 20:47:43 +0100
From:   David Hildenbrand <david@...hat.com>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Gang Li <gang.li@...ux.dev>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Gang Li <ligang.bdlg@...edance.com>
Subject: Re: [RFC PATCH v1 0/4] hugetlb: parallelize hugetlb page allocation
 on boot

On 24.11.23 20:44, David Rientjes wrote:
> On Thu, 23 Nov 2023, David Hildenbrand wrote:
> 
>> On 23.11.23 14:30, Gang Li wrote:
>>> From: Gang Li <ligang.bdlg@...edance.com>
>>>
>>> Inspired by these patches [1][2], this series aims to speed up the
>>> initialization of hugetlb during the boot process through
>>> parallelization.
>>>
>>> It is particularly effective in large systems. On a machine equipped
>>> with 1TB of memory and two NUMA nodes, the time for hugetlb
>>> initialization was reduced from 2 seconds to 1 second.
>>
>> Sorry to say, but why is that a scenario worth adding complexity for /
>> optimizing for? You don't cover that, so there is a clear lack in the
>> motivation.
>>
>> 2 vs. 1 second on a 1 TiB system is usually really just noise.
>>
> 
> The cost will continue to grow over time, so I presume that Gang is trying
> to get out in front of the issue even though it may not be a large savings
> today.
> 
> Running single boot tests, with the latest upstream kernel, allocating
> 1,440 1GB hugetlb pages on a 1.5TB AMD host appears to take 1.47s.
> 
> But allocating 11,776 1GB hugetlb pages on a 12TB Intel host takes 65.2s
> today with the current implementation.

And there, the 65.2s won't be noise because that 12TB system is up by a 
snap of a finger? :)

-- 
Cheers,

David / dhildenb