linux-kernel - Re: [patch] SLQB slab allocator

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]

Date:	Wed, 14 Jan 2009 12:01:32 -0600 (CST)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	Nick Piggin <npiggin@...e.de>
cc:	Pekka Enberg <penberg@...helsinki.fi>,
	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
	Lin Ming <ming.m.lin@...el.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [patch] SLQB slab allocator

On Wed, 14 Jan 2009, Nick Piggin wrote:

> Right, but that regression isn't my only problem with SLUB. I think
> higher order allocations could be much more damaging for more a wider
> class of users. It is less common to see higher order allocation failure
> reports in places other than lkml, where people tend to have systems
> stay up longer and/or do a wider range of things with them.

The higher orders can fail and will then result in the allocator doing
order 0 allocs. It is not a failure condition. Higher orders are an
advantage because they localize variables of the same type and therefore
reduce TLB pressure.

> The idea of removing queues doesn't seem so good to me. Queues are good.
> You amortize or avoid all sorts of things with queues. We have them
> everywhere in the kernel ;)

Queues require maintenance which introduces variability because queue
cleaning has to be done periodically and the queues grow in number if NUMA
scenarios have to be handled effectively. This is a big problem for low
latency applications (like in HPC). Spending far too much time optimizing
queue cleaning in SLAB lead to the SLUB idea.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/