netdev - Re: [PATCH net-next] net: sched: refactor flower walk to iterate over idr

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Date:   Tue, 10 Jul 2018 15:55:44 +0200
From:   Simon Horman <simon.horman@...ronome.com>
To:     Vlad Buslov <vladbu@...lanox.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, jhs@...atatu.com,
        xiyou.wangcong@...il.com, jiri@...nulli.us
Subject: Re: [PATCH net-next] net: sched: refactor flower walk to iterate
 over idr

On Mon, Jul 09, 2018 at 01:29:11PM +0300, Vlad Buslov wrote:
> Extend struct tcf_walker with additional 'cookie' field. It is intended to
> be used by classifier walk implementations to continue iteration directly
> from particular filter, instead of iterating 'skip' number of times.
> 
> Change flower walk implementation to save filter handle in 'cookie'. Each
> time flower walk is called, it looks up filter with saved handle directly
> with idr, instead of iterating over filter linked list 'skip' number of
> times. This change improves complexity of dumping flower classifier from
> quadratic to linearithmic. (assuming idr lookup has logarithmic complexity)
> 
> Reviewed-by: Jiri Pirko <jiri@...lanox.com>
> Signed-off-by: Vlad Buslov <vladbu@...lanox.com>

Reported-by: Simon Horman <simon.horman@...ronome.com>

Thanks, I'm very pleased to see this change. I would appreciate it if
we could have a little time to test its impact on performance thoroughly.

One question: will this work as expected (i.e. be at least backwards
compatible) with existing user-space code?