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From: David Ahern <dsa@cumulusnetworks•com>
To: David Miller <davem@davemloft•net>
Cc: netdev@vger•kernel.org
Subject: Re: [PATCH net-next] net: FIB tracepoints
Date: Thu, 27 Aug 2015 22:12:01 -0700	[thread overview]
Message-ID: <55DFEDA1.2070903@cumulusnetworks.com> (raw)
In-Reply-To: <55DFEC92.8050700@cumulusnetworks.com>

On 8/27/15 10:07 PM, David Ahern wrote:
> On 8/27/15 10:05 PM, David Miller wrote:
>> From: David Ahern <dsa@cumulusnetworks•com>
>> Date: Thu, 27 Aug 2015 21:59:32 -0700
>>
>>> +        __array(    __u8,    src,    4    )
>>> +        __array(    __u8,    dst,    4    )
>>   ...
>>> +        __array(    __u8,    src,    4    )
>>
>> Maybe there is something I don't understand about tracing, but why not
>> use __u32?  If endianness types are the issue, just force cast it as
>> needed.
>>
>> Using a memcpy() on a 4-byte array is kinda excessive.
>>
>
> Silly trick need to use %pI4. ie., printing the addresses as strings vs.
> hex.

perhaps an example helps:

swapper     0 [000]   406.447548: fib:fib_table_lookup: table 255 oif 0 
iif 0 src 0.0.0.0 dst 2.1.1.2 tos 0 scope 0 flags 0

If src and dst are u32's then they print as either 0x%x or %d which is 
not intuitive. I added support to perf for the following printk formats 
with 3d199b5be53:

       %pi4 print an IPv4 address with leading zeros
       %pI4 print an IPv4 address without leading zeros
       %pi6 print an IPv6 address without colons
       %pI6 print an IPv6 address with colons
       %pI6c print an IPv6 address in compressed form with colons
       %pISpc print an IP address from a sockaddr

  reply	other threads:[~2015-08-28  5:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-28  4:59 [PATCH net-next] net: FIB tracepoints David Ahern
2015-08-28  5:05 ` David Miller
2015-08-28  5:07   ` David Ahern
2015-08-28  5:12     ` David Ahern [this message]
2015-08-28  5:17       ` David Miller
2015-08-28  5:32         ` David Ahern
2015-08-28  5:48           ` David Miller
2015-08-28  5:16     ` David Miller
2015-08-28  5:27       ` David Ahern
2015-08-28  5:47         ` David Miller

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