concept prove patch for ktrace output to all file types

Howard Su howard0su at
Fri Jun 29 10:17:10 UTC 2007

On 6/28/07, Robert Watson <rwatson at> wrote:
> What happens to processes associated with the same or other ktrace
> sessions if
> one ktrace session stalls due to a fifo or pipe buffer filling?

I don't think my patch will bring the new problem here. Original, we write
to disk still be blocked due to some things like disk busy, etc.

If my reading is right, ktrace use two way to submit request. ktr_enqueue
will put the request into a queue if it is not safe to enter VFS.
ktr_submitrequest will be used to commit record to disk immediately. in my
case, blocking will be safe there.

The issue about losting some recording to fifo blocking. I don't think we
can solve that in the kernel. It is userland code's responsiblity to read it
to avoid losting data.


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