Dreadlocks – Deadlock Detection in Linux

Supervisor: Dimitri Perelman

By: Dan Slov & Gal Nave

Networked Software Lab

Problem definition:

Deadlock is a specific condition when two or more processes (or threads) are each waiting for each other to release a resource, thus forming a circular chain.

Project goals:• Supply support for successful debugging

•Implement M.Herlihy and E.Koskinen “Dreadlocks” algorithm in Linux.

• Evaluate the performance overhead implied by the solution

What is Digest?Each thread has a list of processes/threads, it is waiting for in order to acquire a mutex lock . This list is called a digest

Deadlock Detection – how it gets done: Thread trying to acquire mutex that is

already locked checks the owner’s digest for its TID and if it is found there – DEADLOCK.

Digest of A:{B}

Digest of B:{A}

New lock algorithm :

Try to lock a mutex

Taken?

Acquire it

try to detect a deadlock

Deadlock?

alert the userno

yes

yes

no