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Wed, 8 Jul 2020 12:06:57 +0000 From: Yash Shah To: Andreas Schwab CC: "Paul Walmsley ( Sifive)" , "palmer@dabbelt.com" , "robh+dt@kernel.org" , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , Sachin Ghadi , "aou@eecs.berkeley.edu" , "anup@brainfault.org" , "lollivier@baylibre.com" , Green Wan , "atish.patra@wdc.com" , "alistair.francis@wdc.com" , "deepa.kernel@gmail.com" , "bmeng.cn@gmail.com" Subject: RE: [PATCH 0/3] Dynamic CPU frequency switching for the HiFive Thread-Topic: [PATCH 0/3] Dynamic CPU frequency switching for the HiFive Thread-Index: AQHWQ9XZeaoAcUonuUqzTiy5jwwbX6jyoJC5gAsX94A= Date: Wed, 8 Jul 2020 12:06:56 +0000 Message-ID: References: <1592308864-30205-1-git-send-email-yash.shah@sifive.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: suse.de; dkim=none (message not signed) header.d=none;suse.de; dmarc=none action=none header.from=sifive.com; 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x-ms-exchange-antispam-messagedata: 3XAjUiBvviMHn9nMcrS/owzjThhZiRv7Wcc6t+66rjxhnsBU0x7y4Oy2vSAaTgJzTfM4zTzf3Kbe/u+vPbgpr0bfG77W+7/AMdKf0X3CByd++CEI/Vq79s35qIQb0Pi/WVQMqrO5awjRFNGST0OnUc2SdMueosDtB2CK9kTe2BQUrjfeO73Y8a4Q3JtffunojfhGxfM3rLMREnCJWuEtA/qT2U34i8bO4dEMQ896AvIfa35BUwmDgfTnrgKzFN3p6VjQ5G6Gn2+jAuyESt7kRJPW+9mRCF9o3By9waYRdn1znRlxBs8oLt7dli8e6GeVKJ8/lv3m0uWfBjo8VhKJ4EwPcGbgOYcatmuR2ZZxWcT9bn8Z5ZUlMHEiRiGnI81pc+AbLdWTeQ2cKzcTgIM9pZwHa49mHI+mvz2Y/9E4kkA0uHk8QZ1ORJ2VJUVIuJ3nqwy62xa1e5bZ+CTshHIKx53VWd1/iXKZvOw8Q3MnVCY= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: sifive.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BN6PR1301MB2020.namprd13.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6a52e268-1343-4efa-a8dc-08d823376968 X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Jul 2020 12:06:56.9946 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 22f88e9d-ae0d-4ed9-b984-cdc9be1529f1 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: +VF7jIYSVa4ShIcJh5C3wPbSD31f5WOpflZG0VcNm6xWCYhM5cNd7UC6izA6H1oO4V1KutbioBiJCTYqJGz/8g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR13MB1108 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andreas, > -----Original Message----- > From: Andreas Schwab > Sent: 01 July 2020 16:11 > To: Yash Shah > Cc: Paul Walmsley ( Sifive) ; > palmer@dabbelt.com; robh+dt@kernel.org; linux-riscv@lists.infradead.org; > linux-kernel@vger.kernel.org; devicetree@vger.kernel.org; Sachin Ghadi > ; aou@eecs.berkeley.edu; anup@brainfault.org; > lollivier@baylibre.com; Green Wan ; > atish.patra@wdc.com; alistair.francis@wdc.com; deepa.kernel@gmail.com; > bmeng.cn@gmail.com > Subject: Re: [PATCH 0/3] Dynamic CPU frequency switching for the HiFive >=20 > [External Email] Do not click links or attachments unless you recognize t= he > sender and know the content is safe >=20 > On Jun 16 2020, Yash Shah wrote: >=20 > > The patch series adds the support for dynamic CPU frequency switching > > for FU540-C000 SoC on the HiFive Unleashed board. All the patches are > > based on Paul Walmsley's work. > > > > This series is based on Linux v5.7 and tested on HiFive unleashed board= . >=20 > I'm using that patch with 5.7.5. >=20 > It appears to interfer with serial output when using the ondemand governo= r. >=20 > I also see soft lockups when using the performance governor: >=20 > [ 101.587527] rcu: INFO: rcu_sched self-detected stall on CPU > [ 101.592322] rcu: 0-...!: (932 ticks this GP) > idle=3D11a/1/0x4000000000000004 softirq=3D4301/4301 fqs=3D4 > [ 101.601432] (t=3D6001 jiffies g=3D4017 q=3D859) [ 101.605514] rcu: r= cu_sched > kthread starved for 5984 jiffies! g4017 f0x0 RCU_GP_WAIT_FQS(5) - > >state=3D0x0 ->cpu=3D2 [ 101.615494] rcu: RCU grace-period kthread stack > dump: > [ 101.620530] rcu_sched R running task 0 10 2 0x00= 000000 > [ 101.627560] Call Trace: > [ 101.630004] [] __schedule+0x25c/0x616 [ 101.635205] > [] schedule+0x42/0xb2 [ 101.640070] > [] schedule_timeout+0x56/0xb8 [ 101.645626] > [] rcu_gp_fqs_loop+0x208/0x248 [ 101.651266] > [] rcu_gp_kthread+0xc2/0xcc [ 101.656651] > [] kthread+0xda/0xec [ 101.661426] [= ] > ret_from_exception+0x0/0xc [ 101.666977] Task dump for CPU 0: > [ 101.670187] loop0 R running task 0 655 2 0x00= 000008 > [ 101.677218] Call Trace: > [ 101.679657] [] walk_stackframe+0x0/0xaa [ > 101.685036] [] show_stack+0x2a/0x34 [ 101.690074] > [] sched_show_task.part.0+0xc2/0xd2 [ 101.696154] > [] sched_show_task+0x64/0x66 [ 101.701618] > [] dump_cpu_task+0x3e/0x48 [ 101.706916] > [] rcu_dump_cpu_stacks+0x94/0xce [ 101.712731] > [] print_cpu_stall+0x116/0x18a [ 101.718375] > [] check_cpu_stall+0xcc/0x1a2 [ 101.723929] > [] rcu_pending.constprop.0+0x36/0xaa [ 101.730094] > [] rcu_sched_clock_irq+0xa6/0xea [ 101.735913] > [] update_process_times+0x1e/0x42 [ 101.741821] > [] tick_sched_handle+0x26/0x52 [ 101.747456] > [] tick_sched_timer+0x6a/0xd0 [ 101.753015] > [] __run_hrtimer.constprop.0+0x50/0xe8 > [ 101.759353] [] __hrtimer_run_queues+0x48/0x6c [ > 101.765254] [] hrtimer_interrupt+0xca/0x1d4 [ > 101.770985] [] riscv_timer_interrupt+0x32/0x3a [ > 101.776976] [] do_IRQ+0xa4/0xb8 [ 101.781663] > [] ret_from_exception+0x0/0xc >=20 > Andreas. >=20 > -- > Andreas Schwab, SUSE Labs, schwab@suse.de GPG Key fingerprint =3D 0196 > BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something > completely different." I am looking into the issues you reported. I will update soon. Thanks for testing. - Yash