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Re: [Qemu-devel] [PATCH v4 00/20] instrument: Add basic event instrument
From: |
Lluís Vilanova |
Subject: |
Re: [Qemu-devel] [PATCH v4 00/20] instrument: Add basic event instrumentation |
Date: |
Mon, 11 Sep 2017 02:31:04 +0300 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) |
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
- [Qemu-devel] [PATCH v4 13/20] instrument: Add event 'guest_cpu_exit', (continued)
- [Qemu-devel] [PATCH v4 13/20] instrument: Add event 'guest_cpu_exit', Lluís Vilanova, 2017/09/06
- [Qemu-devel] [PATCH v4 14/20] instrument: Add event 'guest_cpu_reset', Lluís Vilanova, 2017/09/06
- [Qemu-devel] [PATCH v4 15/20] trace: Introduce a proper structure to describe memory accesses, Lluís Vilanova, 2017/09/06
- [Qemu-devel] [PATCH v4 16/20] instrument: Add event 'guest_mem_before_trans', Lluís Vilanova, 2017/09/06
- [Qemu-devel] [PATCH v4 17/20] instrument: Add event 'guest_mem_before_exec', Lluís Vilanova, 2017/09/06
- [Qemu-devel] [PATCH v4 18/20] instrument: Add event 'guest_user_syscall', Lluís Vilanova, 2017/09/06
- [Qemu-devel] [PATCH v4 19/20] instrument: Add event 'guest_user_syscall_ret', Lluís Vilanova, 2017/09/06
- [Qemu-devel] [PATCH v4 20/20] instrument: Add API to manipulate guest memory, Lluís Vilanova, 2017/09/06
- Re: [Qemu-devel] [PATCH v4 00/20] instrument: Add basic event instrumentation, Emilio G. Cota, 2017/09/06
- Re: [Qemu-devel] [PATCH v4 00/20] instrument: Add basic event instrumentation, Markus Armbruster, 2017/09/07
- Re: [Qemu-devel] [PATCH v4 00/20] instrument: Add basic event instrumentation, Markus Armbruster, 2017/09/07