Messages in this thread | | | Date | Mon, 16 Jan 2012 10:08:40 +0000 | Subject | Re: [PATCH 3/3] KVM: perf: kvm events analysis tool | From | Stefan Hajnoczi <> |
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On Mon, Jan 16, 2012 at 9:32 AM, Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote: > +DESCRIPTION > +----------- > +You can analyze some crucial events and statistics with this > +'perf kvm-events' command.
This line is very general and does not explain which events/statistics can be collected or how you can use that information. I suggest making this description more specific. Explain that this subcommand observers kvm.ko tracepoints and annotates/decodes them with additional information (this is why I would use this command and not raw perf record -e kvm:\*).
> + { SVM_EXIT_MONITOR, "monitor" }, \ > + { SVM_EXIT_MWAIT, "mwait" }, \ > + { SVM_EXIT_XSETBV, "xsetbv" }, \ > + { SVM_EXIT_NPF, "npf" }
All this copy-paste could be avoided by sharing this stuff with the arch/x86/kvm/ code.
> +static void exit_event_decode_key(struct event_key *key, char decode[20]) > +{ > + const char *exit_reason = get_exit_reason(key->info, key->key); > + > + memset(decode, 0, 20); > + strncpy(decode, exit_reason, 20);
This is a bad pattern to follow when using strncpy(3) because if there was a strlen(exit_reason) == 20 string then decode[] would not be NUL-terminated. Right now it's safe but it's better to just use strlcpy() and drop the memset(3).
> +} > + > +static struct kvm_events_ops exit_events = { > + .is_begain_event = exit_event_begain, > + .is_end_event = exit_event_end, > + .get_key = exit_event_get_key, > + .decode_key = exit_event_decode_key, > + .name = "VM-EXIT" > +}; > + > +#define KVM_TRACE_MMIO_READ_UNSATISFIED 0 > +#define KVM_TRACE_MMIO_READ 1 > +#define KVM_TRACE_MMIO_WRITE 2 > +static bool mmio_event_begain(struct event *event, void *data) > +{ > + if (!strcmp(event->name, "kvm_mmio")) { > + long type = raw_field_value(event, "type", data); > + > + if (type != KVM_TRACE_MMIO_READ_UNSATISFIED) > + return true; > + }; > + > + return false; > +} > + > +static bool mmio_event_end(struct event *event) > +{ > + return !strcmp(event->name, "kvm_mmio_done"); > +} > + > +static struct event_key mmio_event_get_key(struct event *event, void *data) > +{ > + struct event_key key; > + > + key.key = raw_field_value(event, "gpa", data); > + key.info = raw_field_value(event, "type", data); > + > + return key; > +} > + > +static void mmio_event_decode_key(struct event_key *key, char decode[20]) > +{ > + memset(decode, 0, 20); > + sprintf(decode, "%#lx:%s", key->key, > + key->info == KVM_TRACE_MMIO_READ ? "R" : "W");
Please drop the memset and use snprintf(3) instead of sprintf(3). It places the NUL-terminator and ensures you don't exceed the buffer size.
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