netdev - Re: [PATCH net-next 0/2] net/sctp: Avoid allocating high order memory with kmalloc()

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Message-ID: <20180724173647.GA8881@localhost.localdomain>
Date:   Tue, 24 Jul 2018 14:36:47 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Konstantin Khorenko <khorenko@...tuozzo.com>
Cc:     oleg.babin@...il.com, netdev@...r.kernel.org,
        linux-sctp@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Vlad Yasevich <vyasevich@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Xin Long <lucien.xin@...il.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>
Subject: Re: [PATCH net-next 0/2] net/sctp: Avoid allocating high order
 memory with kmalloc()

On Tue, Jul 24, 2018 at 06:35:35PM +0300, Konstantin Khorenko wrote:
> Hi Marcelo,
> 
> pity to abandon Oleg's attempt to avoid high order allocations and use
> flex_array instead, so i tried to do the performance measurements with
> options you kindly suggested.

Nice, thanks!

...
> As we can see single stream tests do not show any noticeable degradation,
> and SCTP_*_MANY tests spread decreased significantly when -S/-s options are used,
> but still too big to consider the performance test pass or fail.
> 
> Can you please advise anything else to try - to decrease the dispersion rate -

In addition, you can try also using a veth tunnel or reducing lo mtu
down to 1500, and also make use of sctp tests (need to be after the --
) option -m 1452.  These will alleaviate issues with cwnd handling
that happen on loopback due to the big MTU and minimize issues with
rwnd/buffer size too.

Even with -S, -s, -m and the lower MTU, it is usual to see some
fluctuation, but not that much.

> or can we just consider values are fine and i'm reworking the patch according
> to your comment about sctp_stream_in(asoc, sid)/sctp_stream_in_ptr(stream, sid)
> and that's it?

Ok, thanks. It seems so, yes.

  Marcelo