linux-kernel - Re: [RFC PATCH 5/6] zsmalloc: introduce handle mapping API

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: <jylsgsw4sdja5jrglywg46bskoylnoemcq4x2hrb6g2hb54tmj@jw5i4s32wt26>
Date: Wed, 29 Jan 2025 12:32:55 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Yosry Ahmed <yosry.ahmed@...ux.dev>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Minchan Kim <minchan@...nel.org>, 
	Johannes Weiner <hannes@...xchg.org>, Nhat Pham <nphamcs@...il.com>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 5/6] zsmalloc: introduce handle mapping API

On (25/01/28 17:21), Yosry Ahmed wrote:
> On Tue, Jan 28, 2025 at 06:38:35PM +0900, Sergey Senozhatsky wrote:
> > On (25/01/28 14:29), Sergey Senozhatsky wrote:
> > > Maybe copy-in is just an okay thing to do.  Let me try to measure.
> 
> Yeah seems like the optimization is effective, at least on that
> workload

The workload is just lots of browser tabs (zram is configured as a
swap device), so it's quite representative.

> unless the memcpy() is cheap and avoiding it is not buying as
> much
>
> ...
>
> (do you know if that's the case?).

We run on arm64 and x86_64 on a variety of models from low-cost ones to
high-cost ones.  I probably wouldn't expect memcpy() of 6GB of random
sized objects (loop unrolling is possible only partially) to be cheap
in general.