linux-kernel - Re: [RFC] Unified Ring Buffer (Next Generation)

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: <20100520134838.GA26573@Krystal>
Date:	Thu, 20 May 2010 09:48:38 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Christoph Hellwig <hch@....de>, Li Zefan <lizf@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Tom Zanussi <tzanussi@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [RFC] Unified Ring Buffer (Next Generation)

* Andi Kleen (andi@...stfloor.org) wrote:
> > The plan here is to create a ring buffer that supports per-buffer instance
> > "flags" that specify what must be supported: e.g. either splice() or mmap(),
> > global vs per-cpu buffers, etc.
> 
> And you plan to test all those flags in the hot path? 

No, I plan to make the hot path inline in the caller, so the flags can
statically select the proper behavior at compile-time. We can test flags
dynamically on the slow-path to save space.

[...]

> > 
> > But all in all, I think users needing _something_ to perform system-wide tracing
> > shout a lot louder than users who need to save a few bytes. So let's try to get
> > something good in first, while keeping an eye on the object size, and if it
> > happens to be too large for some users, then they can always implement a
> > slower and less efficient ring_buffer_tiny.c if they feel like it.
> 
> They don't need to, they already have kfifo.
> 

Right.

> > I totally agree with you. This is in good part why I spent a large part of 2009
> > writing papers explaining my ring buffer, doing Promela models and formal proofs
> > of correctness. I think after all that work, the abstractions I will use will be
> > much easier to grap by anyone willing to do a bit of reading.
> 
> Writing papers is not a replacement for simple maintainable code.

True. I rather mean "in addition to simple maintainable code".

Thanks,

Mathieu


-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
--
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/