linux-kernel - Re: kdbus: to merge or not to merge?

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: <55C4C35A.4070306@zonque.org>
Date:	Fri, 7 Aug 2015 16:40:26 +0200
From:	Daniel Mack <daniel@...que.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	David Herrmann <dh.herrmann@...il.com>,
	Tom Gundersen <teg@...m.no>,
	"Kalle A. Sandstrom" <ksandstr@....fi>,
	Greg KH <gregkh@...uxfoundation.org>,
	Borislav Petkov <bp@...en8.de>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Havoc Pennington <havoc.pennington@...il.com>,
	Djalal Harouni <tixxdz@...ndz.org>, cee1 <fykcee1@...il.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: kdbus: to merge or not to merge?

On 08/06/2015 08:43 PM, Andy Lutomirski wrote:
> Nonetheless, it looks like the slice logic (aside: it looks *way* more
> complicated than necessary -- what's wrong with circular buffers)
> will, under most (but not all!) workloads, concentrate access to a
> smallish fraction of the pool.  This is IMO bad, since it means that
> most of the time most of the pool will remain uncommitted.  If, at
> some point, something causes the access pattern to change and hit all
> the pages (even just once), suddenly all of the pools get committed,
> and your memory usage blows up.

That's a general problem with memory overcommitment, and not specific to
kdbus. IOW: You'd have the same problem with a similar logic implemented
in userspace, right?


Daniel

--
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/