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charset="us-ascii" Content-ID: <3D7055E0B69DFF42A74004867F3E6857@namprd15.prod.outlook.com> MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: SA1PR15MB5109.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: afad72a1-dd7f-4cf1-0af3-08d96efa3d1c X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Sep 2021 16:45:29.5315 (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: HEIMEUvNatKR61aSHendB9AySfpQEOvhSRiRcpLab1odBHYq803hm1Tj+rMpiuDQs7yGHQvAATt3UzVblm3HzQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR15MB5078 X-OriginatorOrg: fb.com X-Proofpoint-ORIG-GUID: tKUMguly3w6hAiwsVkqDJt5T8jbduTJb X-Proofpoint-GUID: tKUMguly3w6hAiwsVkqDJt5T8jbduTJb X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-09-03_07:2021-09-03,2021-09-03 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 impostorscore=0 priorityscore=1501 mlxscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 suspectscore=0 spamscore=0 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2108310000 definitions=main-2109030098 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, > On Sep 3, 2021, at 1:27 AM, Peter Zijlstra wrote: > > On Thu, Sep 02, 2021 at 09:57:04AM -0700, Song Liu wrote: > >> +static int >> +intel_pmu_snapshot_branch_stack(struct perf_branch_entry *entries, unsigned int cnt) >> +{ >> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); >> + >> + intel_pmu_disable_all(); >> + intel_pmu_lbr_read(); >> + cnt = min_t(unsigned int, cnt, x86_pmu.lbr_nr); >> + >> + memcpy(entries, cpuc->lbr_entries, sizeof(struct perf_branch_entry) * cnt); >> + intel_pmu_enable_all(0); >> + return cnt; >> +} > > Given this disables the PMI from 'random' contexts, should we not add > IRQ disabling around this to avoid really bad behaviour? Do you mean we should add (instead of not add) IRQ disable? Thanks, Song