Messages in this thread | | | Date | Tue, 14 Jun 2022 19:44:27 +0530 | Subject | Re: Commit 282d8998e997 (srcu: Prevent expedited GPs and blocking readers from consuming CPU) cause qemu boot slow | From | Neeraj Upadhyay <> |
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On 6/14/2022 7:33 PM, zhangfei.gao@foxmail.com wrote: > > > On 2022/6/14 下午8:19, Neeraj Upadhyay wrote: >> >>> >>> 5.18-rc4 based ~8sec >>> >>> 5.19-rc1 ~2m43sec >>> >>> 5.19-rc1+fix1 ~19sec >>> >>> 5.19-rc1-fix2 ~19sec >>> >> >> If you try below diff on top of either 5.19-rc1+fix1 or 5.19-rc1-fix2 >> ; does it show any difference in boot time? >> >> --- a/kernel/rcu/srcutree.c >> +++ b/kernel/rcu/srcutree.c >> @@ -706,7 +706,7 @@ static void srcu_schedule_cbs_snp(struct >> srcu_struct *ssp, struct srcu_node *snp >> */ >> static void srcu_gp_end(struct srcu_struct *ssp) >> { >> - unsigned long cbdelay; >> + unsigned long cbdelay = 1; >> bool cbs; >> bool last_lvl; >> int cpu; >> @@ -726,7 +726,9 @@ static void srcu_gp_end(struct srcu_struct *ssp) >> spin_lock_irq_rcu_node(ssp); >> idx = rcu_seq_state(ssp->srcu_gp_seq); >> WARN_ON_ONCE(idx != SRCU_STATE_SCAN2); >> - cbdelay = !!srcu_get_delay(ssp); >> + if (ULONG_CMP_LT(READ_ONCE(ssp->srcu_gp_seq), >> READ_ONCE(ssp->srcu_gp_seq_needed_exp))) >> + cbdelay = 0; >> + >> WRITE_ONCE(ssp->srcu_last_gp_end, ktime_get_mono_fast_ns()); >> > Test here: > qemu: https://github.com/qemu/qemu/tree/stable-6.1 > kernel: > https://github.com/Linaro/linux-kernel-uadk/tree/uacce-devel-5.19-srcu-test > (in case test patch not clear, push in git tree) > > Hardware: aarch64 > > 1. 5.18-rc6 > real 0m8.402s > user 0m3.015s > sys 0m1.102s > > 2. 5.19-rc1 > real 2m41.433s > user 0m3.097s > sys 0m1.177s > > 3. 5.19-rc1 + fix1 from Paul > real 2m43.404s > user 0m2.880s > sys 0m1.214s > > 4. 5.19-rc1 + fix2: fix1 + Remove "if (!jbase)" block > real 0m15.262s > user 0m3.003s > sys 0m1.033s > > When build kernel in the meantime, load time become longer. > > 5. 5.19-rc1 + fix3: fix1 + SRCU_MAX_NODELAY_PHASE 1000000 > real 0m15.215s > user 0m2.942s > sys 0m1.172s > > 6. 5.19-rc1 + fix4: fix1 + Neeraj's change of srcu_gp_end > real 1m23.936s > user 0m2.969s > sys 0m1.181s >
Thanks for this data. Can you please share below test combo also?
7. 5.19-rc1 + fix5: fix2 + Neeraj's change of srcu_gp_end
8. 5.19-rc1 + fix6: fix3 + Neeraj's change of srcu_gp_end
Thanks Neeraj
> More test details: https://docs.qq.com/doc/DRXdKalFPTVlUbFN5 > > Thanks >
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