Re: [PATCH] trace-cmd: Do not use instance from trace context

[Steven Rostedt <rostedt@goodmis.org>]

On Fri, 29 Jul 2022 17:48:08 -0400
Alexander Aring <aahringo@redhat.com> wrote:

> >
> > Bah, I kept getting confused by when to use instance vs ctx->instance,
> > and I guess I messed this one up.  
> 
> I tested it and it seems to fix the problem..., so if it's not to late:
> 
> Tested-by: Alexander Aring <aahringo@redhat.com>

Not too late. I haven't downloaded the patch from patchwork yet (nor my
other patches).

> 
> I am not sure what I should expect from the PTP time synchronization
> over IP capable interfaces (it never worked for me) but I need to say
> it is significantly slower than kvm time synchronization with vsock
> and I am using only virtual interfaces. On the agents I get a couple
> of:

Well, kvm time synchronization doesn't do much between the host and
guest. And I'm looking at making it do even less. That's because the
kvm synchronization is just "read the offset and shift of the guest
from the host and do the calculations via the reader (trace-cmd
report or kernelshark)". But the P2P is sending packets back and forth
between the host and guest and trying to figure out the round trip
latency.

> 
> CPU 1: 787 events lost
> CPU 5: 3059 events lost
> ...
> 
> the result looks to me like garbage too, my lock states do not make
> any sense...(maybe related due the events lost?)

This should be investigated.

> 
> However I think we should move this discussion to bugzilla?
> 

Sure.

-- Steve