Messages in this thread | | | Date | Thu, 25 Sep 2008 10:29:57 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [RFC PATCH 1/3] Unified trace buffer |
| |
On Thu, 25 Sep 2008, Mathieu Desnoyers wrote: > > We could use a page header instead to contain the "unused_size" > information.
Absolutely. There's no one way to do this.
> I would prefer to put the extended timestamp within the event header > instead of creating a separate entry for this for atomicity concerns > (what happens if a long interrupt executes between the TSCExtend marker > event and the event expecting to be written right next to it ?).
The log entries should be reserved with interrupts disabled anyway, and they are per-CPU, so there are no atomicity issues.
For NMI's, things get more exciting. I'd really prefer NMI's to go to a separate ring buffer entirely, because otherwise consistency gets really hard. Using lockless algorithms for a variable-sized pool of pages is a disaster waiting to happen.
I don't think we can currently necessarily reasonably trace NMI's, but it's something to keep in mind as required support eventually.
Linus
| |