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
More test details: https://docs.qq.com/doc/DRXdKalFPTVlUbFN5
Thanks
