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charset="us-ascii" Content-ID: <93440AC397C1D948B352E8A2FEC2142C@namprd10.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BN0PR10MB5128.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2be9359c-6039-49e4-5d0f-08da335ba7db X-MS-Exchange-CrossTenant-originalarrivaltime: 11 May 2022 14:36:37.7089 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 8tJ/B+HZ+KSz9q4qf6NptG8kXfe7LCjRPhFPsu7v4+28F49uPRW0ikzfAbZhX3HCrt6klAxaz+vVMrDchXW7KA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR10MB2817 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.486,18.0.858 definitions=2022-05-11_07:2022-05-11,2022-05-11 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 mlxlogscore=999 spamscore=0 bulkscore=0 adultscore=0 suspectscore=0 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2205110068 X-Proofpoint-GUID: dWP2pE2Tlh_B-OUnLuUJgD8LqK8AWo3r X-Proofpoint-ORIG-GUID: dWP2pE2Tlh_B-OUnLuUJgD8LqK8AWo3r X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE, SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org > On May 11, 2022, at 10:23 AM, Greg KH wrote: >=20 > On Wed, May 11, 2022 at 02:16:19PM +0000, Chuck Lever III wrote: >>=20 >>=20 >>> On May 11, 2022, at 8:38 AM, Greg KH wrote= : >>>=20 >>> On Wed, May 11, 2022 at 12:03:13PM +0200, Wolfgang Walter wrote: >>>> Hi, >>>>=20 >>>> starting with 5.4.188 wie see a massive performance regression on our >>>> nfs-server. It basically is serving requests very very slowly with cpu >>>> utilization of 100% (with 5.4.187 and earlier it is 10%) so that it is >>>> unusable as a fileserver. >>>>=20 >>>> The culprit are commits (or one of it): >>>>=20 >>>> c32f1041382a88b17da5736886da4a492353a1bb "nfsd: cleanup >>>> nfsd_file_lru_dispose()" >>>> 628adfa21815f74c04724abc85847f24b5dd1645 "nfsd: Containerise filecache >>>> laundrette" >>>>=20 >>>> (upstream 36ebbdb96b694dd9c6b25ad98f2bbd263d022b63 and >>>> 9542e6a643fc69d528dfb3303f145719c61d3050) >>>>=20 >>>> If I revert them in v5.4.192 the kernel works as before and performanc= e is >>>> ok again. >>>>=20 >>>> I did not try to revert them one by one as any disruption of our nfs-s= erver >>>> is a severe problem for us and I'm not sure if they are related. >>>>=20 >>>> 5.10 and 5.15 both always performed very badly on our nfs-server in a >>>> similar way so we were stuck with 5.4. >>>>=20 >>>> I now think this is because of 36ebbdb96b694dd9c6b25ad98f2bbd263d022b6= 3 >>>> and/or 9542e6a643fc69d528dfb3303f145719c61d3050 though I didn't tried = to >>>> revert them in 5.15 yet. >>>=20 >>> Odds are 5.18-rc6 is also a problem? >>=20 >> We believe that >>=20 >> 6b8a94332ee4 ("nfsd: Fix a write performance regression") >>=20 >> addresses the performance regression. It was merged into 5.18-rc. >=20 > And into 5.17.4 if someone wants to try that release. I don't have a lot of time to backport this one myself, so I welcome anyone who wants to apply that commit to their favorite LTS kernel and test it for us. >>> If so, I'll just wait for the fix to get into Linus's tree as this does >>> not seem to be a stable-tree-only issue. >>=20 >> Unfortunately I've received a recent report that the fix introduces >> a "sleep while spinlock is held" for NFSv4.0 in rare cases. >=20 > Ick, not good, any potential fixes for that? Not yet. I was at LSF last week, so I've just started digging into this one. I've confirmed that the report is a real bug, but we still don't know how hard it is to hit it with real workloads. -- Chuck Lever