From mboxrd@z Thu Jan  1 00:00:00 1970
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Subject: Re: [PATCH 3/3] KVM: perf: kvm events analysis tool
Date: Tue, 17 Jan 2012 10:37:11 +0800
Message-ID: <4F14DED7.3030002@linux.vnet.ibm.com>
References: <4F13EE3D.2070602@linux.vnet.ibm.com> <4F13EEC5.8050807@linux.vnet.ibm.com> <CAJSP0QVxR9sYYh_Vr6ZKAU-YrWpjgL5jpiKz2zt7eJxV_kgaOg@mail.gmail.com>
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Cc: Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
To: Stefan Hajnoczi <stefanha@gmail.com>
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On 01/16/2012 06:08 PM, Stefan Hajnoczi wrote:

> 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.
>=20
> This line is very general and does not explain which events/statistic=
s
> 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:\*).
>=20


Okay.

>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD { SVM_EXIT_MONITOR, =EF=BF=BD =EF=BF=
=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD=
 =EF=BF=BD "monitor" }, \
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD { SVM_EXIT_MWAIT, =EF=BF=BD =EF=BF=BD=
 =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =
=EF=BF=BD =EF=BF=BD "mwait" }, \
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD { SVM_EXIT_XSETBV, =EF=BF=BD =EF=BF=BD=
 =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =
=EF=BF=BD =EF=BF=BD"xsetbv" }, \
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD { SVM_EXIT_NPF, =EF=BF=BD =EF=BF=BD =
=EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=
=BF=BD =EF=BF=BD =EF=BF=BD "npf" }
>=20
> All this copy-paste could be avoided by sharing this stuff with the
> arch/x86/kvm/ code.
>=20


I will try to combine them in the next version.

>> +static void exit_event_decode_key(struct event_key *key, char decod=
e[20])
>> +{
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD const char *exit_reason =3D get_exit=
_reason(key->info, key->key);
>> +
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD memset(decode, 0, 20);
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD strncpy(decode, exit_reason, 20);
>=20
> This is a bad pattern to follow when using strncpy(3) because if ther=
e
> was a strlen(exit_reason) =3D=3D 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).
>=20


Good point.

>> +static void mmio_event_decode_key(struct event_key *key, char decod=
e[20])
>> +{
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD memset(decode, 0, 20);
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD sprintf(decode, "%#lx:%s", key->key,
>> + =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=
=BD key->info =3D=3D KVM_TRACE_MMIO_READ ? "R" : "W");
>=20
> 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.
>=20
> Same pattern below.
>=20


Will do, thanks Stefan! :)