netdev - Re: [PATCH net-next v3 1/2] net sched actions: dump more than TCA_ACT_MAX

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Date:   Wed, 19 Apr 2017 07:53:02 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com, jiri@...nulli.us,
        xiyou.wangcong@...il.com
Subject: Re: [PATCH net-next v3 1/2] net sched actions: dump more than
 TCA_ACT_MAX_PRIO actions per batch

On 17-04-19 07:49 AM, Jamal Hadi Salim wrote:
> From: Jamal Hadi Salim <jhs@...atatu.com>
>
> When you dump hundreds of thousands of actions, getting only 32 per
> dump batch even when the socket buffer and memory allocations allow
> is inefficient.
>
> With this change, the user will get as many as possibly fitting
> within the given constraints available to the kernel.
>
> A new top level TLV space is introduced. An attribute
> TCAA_ACT_FLAGS is used to carry the flags indicating the user
> is capable of processing these large dumps. Older user space which
> doesnt set this flag doesnt get the large (than 32) batches.
> The kernel uses the TCAA_ACT_COUNT attribute to tell the user how many
> actions are put in a single batch. As such user space app knows how long
> to iterate (independent of the type of action being dumped)
> instead of hardcoded maximum of 32.
>
> Some results dumping 1.5M actions, first unpatched tc which the
> kernel doesnt help:
>
> prompt$ time -p tc actions ls action gact | grep index | wc -l
> 1500000
> real 1388.43
> user 2.07
> sys 1386.79
>
> Now lets see a patched tc which sets the correct flags when requesting
> a dump:
>
> prompt$ time -p updatedtc actions ls action gact | grep index | wc -l
> 1500000
> real 178.13
> user 2.02
> sys 176.96
>
> Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
> ---
>  MAINTAINERS                    |  1 +
>  include/uapi/linux/rtnetlink.h | 21 +++++++++++++++++++--
>  net/sched/act_api.c            | 43 ++++++++++++++++++++++++++++++++----------
>  3 files changed, 53 insertions(+), 12 deletions(-)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7b4b828..94eadbc 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12198,6 +12198,7 @@ F:	kernel/taskstats.c
>
>  TC subsystem
>  M:	Jamal Hadi Salim <jhs@...atatu.com>
> +M:	Jamal Hadi Salim <jhs@...atatu.com>
>  L:	netdev@...r.kernel.org
>  S:	Maintained
>  F:	include/net/pkt_cls.h

Grrr. I did it again. Sending v4 shortly

cheers,
jamal