Re: [RFC] [PATCH] To improve kretprobe scalability

From: Srinivasa DS
Date: Thu May 22 2008 - 04:43:09 EST

Abhishek Sagar wrote:
On 5/21/08, Srinivasa D S <srinivasa@xxxxxxxxxx> wrote:
1) Instead of having one global lock to protect kretprobe instances
present in kretprobe object and kretprobe hash table. We will have two locks,
one lock for protecting kretprobe hash table and another lock for kretporbe

Is it possible to get rid of the kretprobe hash table itself and lose
the kretprobe_lock? It seems like it is just doing a pid-to-instance
mapping. These return instances could be queued in the "current"
task_struct in a LIFO manner. Mutation to this per-task list can be
done with local irqs off...

There were ideas of storing kretprobe instances in task_struct to get rid of locking, but that would require extending task_struct and catching each task exit, destroying its kretprobe instances. This makes code more invasive.
But in this implementation (global hash table, hashed by task), we
lock only the current task's hash bucket and hence we have fairly low contention.

Srinivasa DS
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at