Emilio G Cota writes: > On Wed, Sep 06, 2017 at 20:22:41 +0300, Lluís Vilanova wrote: >> This series adds an API to add instrumentation events. >> >> It also provides additional APIs for: >> * Controlling tracing events
> hmm didn't Stefan say that tracing should be decoupled from this? I understood decoupling instr from the tracing infrastructure (since tracing events are defined as not stable, and instr must be stable by definition). >> * Peek/poke guest memory >> >> There's still missing APIs for (can be added in later series?): >> * Provide something like tracing's per-vCPU trace states (i.e., so that each >> vCPU can have different instrumentation code). It's still not clear to me if >> we should extend the per-vCPU bitmap with instrumentation events, or >> otherwise >> somehow reuse the bits in tracing events (since they're currently limited). > As I said in the description of my alternative implementation [*], I don't see > much value in having per-vCPU events, as most instrumenters just care about > the guest application/system. I can only think of cases where the instrumenter > is only interested in a guest process (in system-mode), but that'd be ugly > anyway (would need to change both QEMU and the guest kernel to track the pid). > If the need ever arises, we could add __vcpu(cpu_index) registration > functions. > [*] https://lists.gnu.org/archive/html/qemu-devel/2017-09/msg01446.html Sorry, your series slipped my radar. I'll take a look at it. Thanks, Lluis
