Knowing how long we spend in firmware calls is an important part of
minimising OS jitter.
This patch adds tracepoints to each OPAL call. If tracepoints are
enabled we branch out to a common routine that calls an entry and exit
tracepoint.
This allows us to write tools that monitor the frequency and duration
of OPAL calls, eg:
name count total(ms) min(ms) max(ms) avg(ms) period(ms)
OPAL_HANDLE_INTERRUPT 5 0.199 0.037 0.042 0.040 12547.545
OPAL_POLL_EVENTS 204 2.590 0.012 0.036 0.013 2264.899
OPAL_PCI_MSI_EOI 2830 3.066 0.001 0.005 0.001 81.166
We use jump labels if configured, which means we only add a single
nop instruction to every OPAL call when the tracepoints are disabled.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
c49f63530b