Messages in this thread | | | Date | Mon, 6 Sep 2021 10:13:43 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH v2] trace: Add migrate-disabled counter to tracing output. |
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On 2021-09-03 19:42:16 [-0400], Steven Rostedt wrote: Hi Steven,
> BTW, > > When doing a v2, always create a new thread. Never send it as a reply to > the previous patch. The reason I missed this is because replies to previous > patches do not end up in my internal patchwork. And I only look at that for > patches. Not my INBOX.
oki.
> > > --- a/kernel/trace/trace_events.c > > +++ b/kernel/trace/trace_events.c > > @@ -181,7 +181,8 @@ static int trace_define_common_fields(void) > > > > __common_field(unsigned short, type); > > __common_field(unsigned char, flags); > > - __common_field(unsigned char, preempt_count); > > + /* XXX */ > > + __common_field(unsigned char, preempt_mg_count); > > __common_field(int, pid); > > > > return ret; > > I'm going to have to nuke this hunk of the patch, and update all the other > locations that have preempt_mg_count in it. Because I just tested it, and > this breaks user space.
I left that with that XXX on purpose so you can look and comment and say how to fix it. The problem I had with preempt_count was that only the lower nibble contains the preemption counter. So I thought you could easily came up with something how this can be split or taught to only expose the lower nibble. I didn't after a few attempts. My understanding is that this `preempt_count' is also used in the filter tracefs file so something like "preempt_count > 1" > filter would also match for migrate_count = 2, preempt_count = 1. You seem to be happy to filter in user space.
Sebastian
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