netdev - Re: [PATCH net-next] ipv6: let trace_fib6_table

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Message-ID: <20171019172613.cewlo6ctggzmauyi@kafai-mbp.dhcp.thefacebook.com>
Date:   Thu, 19 Oct 2017 10:26:13 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     Paolo Abeni <pabeni@...hat.com>
CC:     <netdev@...r.kernel.org>, "David S. Miller" <davem@...emloft.net>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        David Ahern <dsa@...ulusnetworks.com>
Subject: Re: [PATCH net-next] ipv6: let trace_fib6_table_lookup() dereference
 the fib table

On Thu, Oct 19, 2017 at 07:31:43AM +0000, Paolo Abeni wrote:
> The perf traces for ipv6 routing code show a relevant cost around
> trace_fib6_table_lookup(), even if no trace is enabled. This is
> due to the fib6_table de-referencing currently performed by the
> caller.
> 
> Let's the tracing code pay this overhead, passing to the trace
> helper the table pointer. This gives small but measurable
> performance improvement under UDP flood.
> 
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Acked-by: Martin KaFai Lau <kafai@...com>