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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: dddd2585-0cec-4077-07c1-08d78fb40178 X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Jan 2020 18:45:57.6743 (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: eVnaOzRrY++qkAKy1R2kPICqXCbAG6nyY7NqhnhfThzLHOFUDzd0MD7dxq7MqF90nz4jR2sD6fsGrOi3Di9eng== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2949 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2020-01-02_06:2020-01-02,2020-01-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 phishscore=0 bulkscore=0 adultscore=0 mlxlogscore=923 suspectscore=0 spamscore=0 lowpriorityscore=0 mlxscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 clxscore=1011 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-2001020154 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter,=20 > On Dec 17, 2019, at 9:59 AM, Song Liu wrote: >=20 > This patch tries to enable PMU sharing. When multiple perf_events are > counting the same metric, they can share the hardware PMU counter. We > call these events as "compatible events". >=20 > The PMU sharing are limited to events within the same perf_event_context > (ctx). When a event is installed or enabled, search the ctx for compatibl= e > events. This is implemented in perf_event_setup_dup(). One of these > compatible events are picked as the master (stored in event->dup_master). > Similarly, when the event is removed or disabled, perf_event_remove_dup() > is used to clean up sharing. >=20 > A new state PERF_EVENT_STATE_ENABLED is introduced for the master event. > This state is used when the slave event is ACTIVE, but the master event > is not. >=20 > On the critical paths (add, del read), sharing PMU counters doesn't > increase the complexity. Helper functions event_pmu_[add|del|read]() are > introduced to cover these cases. All these functions have O(1) time > complexity. >=20 > Cc: Peter Zijlstra > Cc: Arnaldo Carvalho de Melo > Cc: Jiri Olsa > Cc: Alexey Budankov > Cc: Namhyung Kim > Cc: Tejun Heo > Signed-off-by: Song Liu Happy New Year! Wish you a great 2020! Could you please share feedbacks on this version?=20 Thanks, Song