Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Song Liu <songliubraving@fb.com>
To:     Jiri Olsa <jolsa@redhat.com>
CC:     Song Liu <song@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Kernel Team <Kernel-team@fb.com>,
        "acme@kernel.org" <acme@kernel.org>,
        "acme@redhat.com" <acme@redhat.com>,
        "namhyung@kernel.org" <namhyung@kernel.org>,
        "jolsa@kernel.org" <jolsa@kernel.org>
Subject: Re: [PATCH v5 5/5] perf-stat: introduce bpf_counter_ops->disable()
Thread-Topic: [PATCH v5 5/5] perf-stat: introduce bpf_counter_ops->disable()
Thread-Index: AQHXOhwex5gB4i62NU+zgG+lriKiJqrHUbkAgAAOWgCAAO6+AIAAdISAgANZnwA=
Date:   Thu, 29 Apr 2021 22:40:01 +0000
Message-ID: <7DBDECAE-D100-44C0-B5D3-DE48631430B5@fb.com>
References: <20210425214333.1090950-1-song@kernel.org>
 <20210425214333.1090950-6-song@kernel.org> <YIcwRj4WtsZln4SR@krava>
 <CDBE5630-F7F0-494D-BFA8-33742D831C2D@fb.com> <YIgElir6KJCoygX5@krava>
 <5257A59A-CC47-4CA7-9C15-CD6E20DC4BD0@fb.com>
In-Reply-To: <5257A59A-CC47-4CA7-9C15-CD6E20DC4BD0@fb.com>
Accept-Language: en-US
Content-Language: en-US
Content-Type: text/plain; charset="us-ascii"
Content-ID: <D467AC954697C948B5210CAF609838BB@namprd15.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 9ef9b241-ccfd-452d-b269-08d90b5fb98e
X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Apr 2021 22:40:01.1341
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: u6FhNU24YHoUnf00AbDEH1eAcNZc+v0OseqhSgQBCBcmMQomRPA68U9xkklQ+QHQMx6hADUuXLk6e1y8EkRB9Q==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR15MB3169
X-OriginatorOrg: fb.com
X-Proofpoint-ORIG-GUID: L054yL6uRi_11SuLHaPKf63aIr3AabqX
X-Proofpoint-GUID: L054yL6uRi_11SuLHaPKf63aIr3AabqX
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761
 definitions=2021-04-29_13:2021-04-28,2021-04-29 signatures=0
X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0
 lowpriorityscore=0 mlxscore=0 impostorscore=0 suspectscore=0
 mlxlogscore=999 phishscore=0 priorityscore=1501 spamscore=0 adultscore=0
 clxscore=1015 malwarescore=0 classifier=spam adjust=0 reason=mlx
 scancount=1 engine=8.12.0-2104060000 definitions=main-2104290143
X-FB-Internal: deliver
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


> On Apr 27, 2021, at 12:30 PM, Song Liu <songliubraving@fb.com> wrote:
>=20
>=20
>=20
>> On Apr 27, 2021, at 5:33 AM, Jiri Olsa <jolsa@redhat.com> wrote:
>>=20
>> On Mon, Apr 26, 2021 at 10:18:57PM +0000, Song Liu wrote:
>>>=20
>>>=20
>>>> On Apr 26, 2021, at 2:27 PM, Jiri Olsa <jolsa@redhat.com> wrote:
>>>>=20
>>>> On Sun, Apr 25, 2021 at 02:43:33PM -0700, Song Liu wrote:
>>>>=20
>>>> SNIP
>>>>=20
>>>>> +static inline int bpf_counter__disable(struct evsel *evsel __maybe_u=
nused)
>>>>> +{
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> static inline int bpf_counter__read(struct evsel *evsel __maybe_unuse=
d)
>>>>> {
>>>>> 	return -EAGAIN;
>>>>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>>>>> index d29a8a118973c..e71041c890102 100644
>>>>> --- a/tools/perf/util/evlist.c
>>>>> +++ b/tools/perf/util/evlist.c
>>>>> @@ -17,6 +17,7 @@
>>>>> #include "evsel.h"
>>>>> #include "debug.h"
>>>>> #include "units.h"
>>>>> +#include "bpf_counter.h"
>>>>> #include <internal/lib.h> // page_size
>>>>> #include "affinity.h"
>>>>> #include "../perf.h"
>>>>> @@ -421,6 +422,9 @@ static void __evlist__disable(struct evlist *evli=
st, char *evsel_name)
>>>>> 	if (affinity__setup(&affinity) < 0)
>>>>> 		return;
>>>>>=20
>>>>> +	evlist__for_each_entry(evlist, pos)
>>>>> +		bpf_counter__disable(pos);
>>>>=20
>>>> I was wondering why you don't check evsel__is_bpf like
>>>> for the enable case.. and realized that we don't skip
>>>> bpf evsels in __evlist__enable and __evlist__disable
>>>> like we do in read_affinity_counters
>>>>=20
>>>> so I guess there's extra affinity setup and bunch of
>>>> wrong ioctls being called?
>>>=20
>>> We actually didn't do wrong ioctls because the following check:
>>>=20
>>>      if (... || !pos->core.fd)
>>>               continue;
>>>=20
>>> in __evlist__enable and __evlist__disable. That we don't allocate=20
>>> core.fd for is_bpf events.=20
>>>=20
>>> It is probably good to be more safe with an extra check of=20
>>> evsel__is_bpf(). But it is not required with current code.=20
>>=20
>> hum, but it will do all the affinity setup no? for no reason,
>> if there's no non-bpb event
>=20
> Yes, it will do the affinity setup. Let me see how to get something
> like all_counters_use_bpf here (or within builtin-stat.c).
>=20

Would something like the following work? It is not clean (skipping some=20
useful logic in __evlist__[enable|disable]). But it seems to work in the
tests.

Thanks,
Song


From ecb75a1fa747ca5521bcda972840df1e97c09b11 Mon Sep 17 00:00:00 2001
From: Song Liu <song@kernel.org>
Date: Wed, 28 Apr 2021 17:41:28 -0700
Subject: [PATCH] perf-stat: skip evlist__[enable|disable] when all events u=
ses
 BPF

When all events of a perf-stat session use BPF, it is not necessary to
call evlist__enable() and evlist__disable(). Skip them when
all_counters_use_bpf is true.

Signed-off-by: Song Liu <song@kernel.org>
---
 tools/perf/builtin-stat.c | 12 +++++++++---
 tools/perf/util/evlist.c  |  3 ---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 5a830ae09418e..44459e0352fda 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -572,7 +572,8 @@ static int enable_counters(void)
         * - we have initial delay configured
         */
        if (!target__none(&target) || stat_config.initial_delay) {
-               evlist__enable(evsel_list);
+               if (!all_counters_use_bpf)
+                       evlist__enable(evsel_list);
                if (stat_config.initial_delay > 0)
                        pr_info(EVLIST_ENABLED_MSG);
        }
@@ -581,13 +582,18 @@ static int enable_counters(void)

 static void disable_counters(void)
 {
+       struct evsel *counter;
        /*
         * If we don't have tracee (attaching to task or cpu), counters may
         * still be running. To get accurate group ratios, we must stop gro=
ups
         * from counting before reading their constituent counters.
         */
-       if (!target__none(&target))
-               evlist__disable(evsel_list);
+       if (!target__none(&target)) {
+               evlist__for_each_entry(evsel_list, counter)
+                       bpf_counter__disable(counter);
+               if (!all_counters_use_bpf)
+                       evlist__disable(evsel_list);
+       }
 }

 static volatile int workload_exec_errno;
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 6e5c41528c7d0..6ea3e677dc1e7 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -425,9 +425,6 @@ static void __evlist__disable(struct evlist *evlist, ch=
ar *evsel_name)
        if (affinity__setup(&affinity) < 0)
                return;

-       evlist__for_each_entry(evlist, pos)
-               bpf_counter__disable(pos);
-
        /* Disable 'immediate' events last */
        for (imm =3D 0; imm <=3D 1; imm++) {
                evlist__for_each_cpu(evlist, i, cpu) {
--
2.30.2

=20