linux-kernel - Re: [RESEND PATCH 0/11] kernel:lockdep:replace DFS with BFS

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: <d82e647a0907160012p4f4ee559q1a04be4cfbc4753c@mail.gmail.com>
Date:	Thu, 16 Jul 2009 15:12:37 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	mingo@...e.hu, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [RESEND PATCH 0/11] kernel:lockdep:replace DFS with BFS

2009/7/16 Peter Zijlstra <a.p.zijlstra@...llo.nl>:
>
> I've asked several times to comment on the removal of that generation
> count DaveM did. Is that a normal part of DFS, or was that an
> optimization on top particular to this problem, can something similar be
> done for BFS, etc.

DFS uses generation count DaveM did to decide if a class is visted, and BFS
uses bitmap to mark a class is visted or not and the extra efficiency loss is

          bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);

before staring each BFS.

On most of ARCH, bimap_zero can be optimizied to only consume very few
instructions,
can't it?

It seems bitmap is more easily used in BFS than generation count.

>
> Other than that it does seem to hold up, I've got the patches running on
> my laptop. Don't worry they're not getting lost.

Great.

-- 
Lei Ming
--
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/