linux-kernel - Re: [PATCH v3] Weighted interleave auto-tuning

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: <Z4_9Z_TfVY3VOMHg@gourry-fedora-PF4VCD3F>
Date: Tue, 21 Jan 2025 15:02:47 -0500
From: Gregory Price <gourry@...rry.net>
To: Honggyu Kim <honggyu.kim@...com>
Cc: "Huang, Ying" <ying.huang@...ux.alibaba.com>,
	Joshua Hahn <joshua.hahnjy@...il.com>, kernel_team@...ynix.com,
	hyeonggon.yoo@...com, rafael@...nel.org, lenb@...nel.org,
	gregkh@...uxfoundation.org, akpm@...ux-foundation.org,
	rakie.kim@...com, dan.j.williams@...el.com,
	Jonathan.Cameron@...wei.com, dave.jiang@...el.com,
	horen.chuang@...ux.dev, hannes@...xchg.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-mm@...ck.org, kernel-team@...a.com
Subject: Re: [PATCH v3] Weighted interleave auto-tuning

On Tue, Jan 21, 2025 at 08:27:17PM +0900, Honggyu Kim wrote:
> Hi Ying and Joshua,
> > IMHO, this interface is somewhat hard to be used.  Users need to know
> > which value is legal.  So, this will become something like,
> > 
> > $ cat mode
> > auto [manual]
> > $ echo auto > mode
> > $ cat mode
> > [auto] manual
> 
> This is exactly I internally proposed to Hyeonggon, but couldn't share
> the idea directly here.
> 
> That also makes sense, but I feel like somewhat vague what "auto" false
> means. The "auto" might be better to be "use_hmat" instead and this
> makes "use_hmat" false more meaningful. "use_hmat_weight" or
> "use_hmat_info" might be another candidates.
> 

I don't think we want to encode hmat-ism into the uapi. In fact,
mempolicy doesn't even know about hmat.  It just gets source information
from *somewhere* and applies it accordingly.

I think what you might be asking for is

auto -> [true, false]

if auto=true
  mode -> [default,
           read_bw, write_bw, combined_bw,
           read_ltc, write_ltc, combined_ltc]
if auto=false
  mode -> [disabled]

Where default mode is the kernel selection of whatever combination of
read/write bw/ltc data, and user could switch the attribute.

HOWEVER, such `mode` would require us to cache the attribute structure
per-node, and maybe some thought on what's reasonable, so that I would
prefer that to be a completely different feature / discussion.

~Gregory