netdev - Re: [PATCH v5 net 6/6] net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting

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Date: Fri, 9 Jun 2023 17:20:10 -0700
From: Peilin Ye <yepeilin.cs@...il.com>
To: Vlad Buslov <vladbu@...dia.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>, Jakub Kicinski <kuba@...nel.org>,
	Pedro Tammela <pctammela@...atatu.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
	Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>,
	Peilin Ye <peilin.ye@...edance.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	John Fastabend <john.fastabend@...il.com>,
	Hillf Danton <hdanton@...a.com>, netdev@...r.kernel.org,
	Cong Wang <cong.wang@...edance.com>
Subject: Re: [PATCH v5 net 6/6] net/sched: qdisc_destroy() old ingress and
 clsact Qdiscs before grafting

On Thu, Jun 08, 2023 at 12:17:27PM +0300, Vlad Buslov wrote:
> > When I didn't specify "prio", sometimes that
> > rhashtable_lookup_insert_fast() call in fl_ht_insert_unique() returns
> > -EEXIST.  Is it because that concurrent add-filter requests auto-allocated
> > the same "prio" number, so they collided with each other?  Do you think
> > this is related to why it's slow?
> 
> It is slow because when creating a filter without providing priority you
> are basically measuring the latency of creating a whole flower
> classifier instance (multiple memory allocation, initialization of all
> kinds of idrs, hash tables and locks, updating tp list in chain, etc.),
> not just a single filter, so significantly higher latency is expected.

Ah, I see.  Thanks for the explanation.

Thanks,
Peilin Ye