Hi Andreas, > -----Original Message----- > From: Andreas Schwab <schwab@xxxxxxx> > Sent: 01 July 2020 16:11 > To: Yash Shah <yash.shah@xxxxxxxxxx> > Cc: Paul Walmsley ( Sifive) <paul.walmsley@xxxxxxxxxx>; > palmer@xxxxxxxxxxx; robh+dt@xxxxxxxxxx; linux-riscv@xxxxxxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; Sachin Ghadi > <sachin.ghadi@xxxxxxxxxx>; aou@xxxxxxxxxxxxxxxxx; anup@xxxxxxxxxxxxxx; > lollivier@xxxxxxxxxxxx; Green Wan <green.wan@xxxxxxxxxx>; > atish.patra@xxxxxxx; alistair.francis@xxxxxxx; deepa.kernel@xxxxxxxxx; > bmeng.cn@xxxxxxxxx > Subject: Re: [PATCH 0/3] Dynamic CPU frequency switching for the HiFive > > [External Email] Do not click links or attachments unless you recognize the > sender and know the content is safe > > On Jun 16 2020, Yash Shah wrote: > > > 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. > > I'm using that patch with 5.7.5. > > It appears to interfer with serial output when using the ondemand governor. > > I also see soft lockups when using the performance governor: > > [ 101.587527] rcu: INFO: rcu_sched self-detected stall on CPU > [ 101.592322] rcu: 0-...!: (932 ticks this GP) > idle=11a/1/0x4000000000000004 softirq=4301/4301 fqs=4 > [ 101.601432] (t=6001 jiffies g=4017 q=859) [ 101.605514] rcu: rcu_sched > kthread starved for 5984 jiffies! g4017 f0x0 RCU_GP_WAIT_FQS(5) - > >state=0x0 ->cpu=2 [ 101.615494] rcu: RCU grace-period kthread stack > dump: > [ 101.620530] rcu_sched R running task 0 10 2 0x00000000 > [ 101.627560] Call Trace: > [ 101.630004] [<ffffffe00085a7e2>] __schedule+0x25c/0x616 [ 101.635205] > [<ffffffe00085abde>] schedule+0x42/0xb2 [ 101.640070] > [<ffffffe00085d0ba>] schedule_timeout+0x56/0xb8 [ 101.645626] > [<ffffffe000263c34>] rcu_gp_fqs_loop+0x208/0x248 [ 101.651266] > [<ffffffe0002666de>] rcu_gp_kthread+0xc2/0xcc [ 101.656651] > [<ffffffe00022654e>] kthread+0xda/0xec [ 101.661426] [<ffffffe00020140a>] > ret_from_exception+0x0/0xc [ 101.666977] Task dump for CPU 0: > [ 101.670187] loop0 R running task 0 655 2 0x00000008 > [ 101.677218] Call Trace: > [ 101.679657] [<ffffffe0002028ae>] walk_stackframe+0x0/0xaa [ > 101.685036] [<ffffffe000202b76>] show_stack+0x2a/0x34 [ 101.690074] > [<ffffffe0002319b0>] sched_show_task.part.0+0xc2/0xd2 [ 101.696154] > [<ffffffe00022bb9c>] sched_show_task+0x64/0x66 [ 101.701618] > [<ffffffe000231afe>] dump_cpu_task+0x3e/0x48 [ 101.706916] > [<ffffffe000267762>] rcu_dump_cpu_stacks+0x94/0xce [ 101.712731] > [<ffffffe0002631f6>] print_cpu_stall+0x116/0x18a [ 101.718375] > [<ffffffe000264a46>] check_cpu_stall+0xcc/0x1a2 [ 101.723929] > [<ffffffe000264b52>] rcu_pending.constprop.0+0x36/0xaa [ 101.730094] > [<ffffffe000266ab2>] rcu_sched_clock_irq+0xa6/0xea [ 101.735913] > [<ffffffe00026d1be>] update_process_times+0x1e/0x42 [ 101.741821] > [<ffffffe0002793bc>] tick_sched_handle+0x26/0x52 [ 101.747456] > [<ffffffe0002798fe>] tick_sched_timer+0x6a/0xd0 [ 101.753015] > [<ffffffe00026d9be>] __run_hrtimer.constprop.0+0x50/0xe8 > [ 101.759353] [<ffffffe00026da9e>] __hrtimer_run_queues+0x48/0x6c [ > 101.765254] [<ffffffe00026e410>] hrtimer_interrupt+0xca/0x1d4 [ > 101.770985] [<ffffffe0006ceef8>] riscv_timer_interrupt+0x32/0x3a [ > 101.776976] [<ffffffe00085e17c>] do_IRQ+0xa4/0xb8 [ 101.781663] > [<ffffffe00020140a>] ret_from_exception+0x0/0xc > > Andreas. > > -- > Andreas Schwab, SUSE Labs, schwab@xxxxxxx GPG Key fingerprint = 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
