From: Leon Romanovsky <leonro@nvidia.com>
To: Tao Liu <thomas.liu@ucloud.cn>
Cc: <linux-rdma@vger.kernel.org>, <saeedm@nvidia.com>,
<talgi@nvidia.com>, <mgurtovoy@nvidia.com>, <jgg@nvidia.com>,
<yaminf@nvidia.com>
Subject: Re: [PATCH RFC net] linux/dim: Fix divide 0 in RDMA DIM.
Date: Mon, 27 Jun 2022 10:42:02 +0300 [thread overview]
Message-ID: <YrlfSnNNdjkaajAg@unreal> (raw)
In-Reply-To: <20220623085858.42945-1-thomas.liu@ucloud.cn>
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@ucloud.cn>
> ---
> 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)
>
next prev parent reply other threads:[~2022-06-27 7:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-23 8:58 [PATCH RFC net] linux/dim: Fix divide 0 in RDMA DIM Tao Liu
2022-06-27 3:32 ` Tao Liu
2022-06-27 7:42 ` Leon Romanovsky [this message]
2022-06-27 8:45 ` Tao Liu
2022-06-27 8:57 ` Leon Romanovsky
2022-06-27 10:23 ` Tao Liu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YrlfSnNNdjkaajAg@unreal \
--to=leonro@nvidia.com \
--cc=jgg@nvidia.com \
--cc=linux-rdma@vger.kernel.org \
--cc=mgurtovoy@nvidia.com \
--cc=saeedm@nvidia.com \
--cc=talgi@nvidia.com \
--cc=thomas.liu@ucloud.cn \
--cc=yaminf@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.