On Thu, Jun 23, 2022 at 04:58:58PM +0800, Tao Liu wrote:
> We hit a divide 0 error in ofed 5.1.2.3.7.1. But dim.c and
> rdma_dim.c seem same as upstream.
>
> CallTrace:
> Hardware name: H3C R4900 G3/RS33M2C9S, BIOS 2.00.37P21 03/12/2020
> task: ffff880194b78000 task.stack: ffffc90006714000
> RIP: 0010:backport_rdma_dim+0x10e/0x240 [mlx_compat]
> RSP: 0018:ffff880c10e83ec0 EFLAGS: 00010202
> RAX: 0000000000002710 RBX: ffff88096cd7f780 RCX: 0000000000000064
> RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
> RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 000000001d7c6c09
> R13: ffff88096cd7f780 R14: ffff880b174fe800 R15: 0000000000000000
> FS: 0000000000000000(0000) GS:ffff880c10e80000(0000)
> knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000a0965b00 CR3: 000000000200a003 CR4: 00000000007606e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
> <IRQ>
> ib_poll_handler+0x43/0x80 [ib_core]
> irq_poll_softirq+0xae/0x110
> __do_softirq+0xd1/0x28c
> irq_exit+0xde/0xf0
> do_IRQ+0x54/0xe0
> common_interrupt+0x8f/0x8f
> </IRQ>
> ? cpuidle_enter_state+0xd9/0x2a0
> ? cpuidle_enter_state+0xc7/0x2a0
> ? do_idle+0x170/0x1d0
> ? cpu_startup_entry+0x6f/0x80
> ? start_secondary+0x1b9/0x210
> ? secondary_startup_64+0xa5/0xb0
> Code: 0f 87 e1 00 00 00 8b 4c 24 14 44 8b 43 14 89 c8 4d 63 c8 44 29 c0 99 31 d0 29 d0 31 d2 48 98 48 8d 04 80 48 8d 04 80 48 c1 e0 02 <49> f7 f1 48 83 f8 0a 0f 86 c1 00 00 00 44 39 c1 7f 10 48 89 df
> RIP: backport_rdma_dim+0x10e/0x240 [mlx_compat] RSP: ffff880c10e83ec0
>
> crash> struct dim ffff88096cd7f780
> struct dim {
> state = 1 '\001',
> prev_stats = {
> ppms = 2142150514,
> bpms = 391112768,
> epms = -30709,
> cpms = 1,
> cpe_ratio = 0
> },
> start_sample = {
> time = 51174507127193614,
> pkt_ctr = 0,
> byte_ctr = 0,
> event_ctr = 1,
> comp_ctr = 494693321
> },
> measuring_sample = {
> time = 51174507266581985,
> pkt_ctr = 0,
> byte_ctr = 0,
> event_ctr = 65,
> comp_ctr = 494693385
> },
> work = {
> data = {
> counter = 128
> },
> entry = {
> next = 0xffff88096cd7f7d0,
> prev = 0xffff88096cd7f7d0
> },
> func = 0xffffffffa02b9f80
> },
> priv = 0xffff880b174fe800,
> profile_ix = 1 '\001',
> mode = 0 '\000',
> tune_state = 2 '\002',
> steps_right = 1 '\001',
> steps_left = 1 '\001',
> tired = 0 '\000'
> }
>
> Fixes: f4915455dcf0 ("linux/dim: Implement RDMA adaptive moderation (DIM)")
> Signed-off-by: Tao Liu <thomas.liu@xxxxxxxxx>
> ---
> lib/dim/rdma_dim.c | 3 +++
> 1 file changed, 3 insertions(+)
I think that this change will be better as it won't change
decision order in rdma_dim_stats_compare()
diff --git a/include/linux/dim.h b/include/linux/dim.h
index b698266d0035..69ae238ec2dc 100644
--- a/include/linux/dim.h
+++ b/include/linux/dim.h
@@ -21,7 +21,7 @@
* We consider 10% difference as significant.
*/
#define IS_SIGNIFICANT_DIFF(val, ref) \
- (((100UL * abs((val) - (ref))) / (ref)) > 10)
+ (ref && (((100UL * abs((val) - (ref))) / (ref)) > 10))
/*
* Calculate the gap between two values.
>
> diff --git a/lib/dim/rdma_dim.c b/lib/dim/rdma_dim.c
> index 15462d54758d..a657b106343c 100644
> --- a/lib/dim/rdma_dim.c
> +++ b/lib/dim/rdma_dim.c
> @@ -34,6 +34,9 @@ static int rdma_dim_stats_compare(struct dim_stats *curr,
> return (curr->cpms > prev->cpms) ? DIM_STATS_BETTER :
> DIM_STATS_WORSE;
>
> + if (!prev->cpe_ratio)
> + return DIM_STATS_SAME;
> +
> if (IS_SIGNIFICANT_DIFF(curr->cpe_ratio, prev->cpe_ratio))
> return (curr->cpe_ratio > prev->cpe_ratio) ? DIM_STATS_BETTER :
> DIM_STATS_WORSE;
> --
> 2.30.1 (Apple Git-130)
>
