Softirq preemption

[Lee Revell <rlrevell@joe-job.com>]

Ingo,

Is there any chance that the softirq preemption feature from the -rt
kernel can be pushed upstream?

Currently I am testing 2.6.14-rt21 with PREEMPT_DESKTOP and hard/softirq
preemption disabled in order to simulate the behavior of 2.6.14
mainline.  The network TX softirq is the longest non-preemptible code
path, it can run for 5-6ms.  However I can see that the preempt_count
drops to zero on many occasions, which IIRC means that no locks are held
and we could easily preempt at that point.

Without softirq	preemption I don't see how we have any chance of meeting
the 1ms goal for desktop responsiveness that was decided on at OLS 2004.

Lee

Attachment: softirq-tx.trace.gz
Description: GNU Zip compressed data