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SubjectRe: [RESEND PATCH 0/11] kernel:lockdep:replace DFS with BFS
2009/7/13 Peter Zijlstra <>:
> On Sun, 2009-06-28 at 23:04 +0800, wrote:
>> Hi,Peter
>> Currently lockdep uses recursion DFS(depth-first search) algorithm to
>> search target in checking lock circle(check_noncircular()),irq-safe
>> -> irq-unsafe(check_irq_usage()) and irq inversion when adding a new
>> lock dependency. This patches replace the current DFS with BFS, based on
>> the following consideration:
>>     1,no loss of efficiency, no matter DFS or BFS, the running time
>>     are O(V+E) (V is vertex count, and E is edge count of one
>>     graph);
> I'd still like to get some feedback on the loss of that generation count
> optimization done by DaveM, I haven't had time to analyze the
> ramifications of that.

Hi, Ingo and Peter

As you said, BFS patch-set is valuable(decrease kernel stack consume
largely, and report
the shortest circle).

It has been pending on lkml silently for several monthes, and I hope
it may be merged to
tip-tree or other tree. I don't know what we should and can do to make
it being accepted by tip-tree.
Anyway, I'd like to do any fixes for it to be merged.

Any suggestions, ideas or objections?


Lei Ming
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