Re: [dpdk-dev] [PATCH v2] app/testpmd: fix testpmd packets dump overlapping

["Jiawei(Jonny) Wang" <jiaweiw@nvidia.com>]

Hi Ferruh,

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> Sent: Tuesday, November 17, 2020 8:07 PM
> To: Jiawei(Jonny) Wang <jiaweiw@nvidia.com>; wenzhuo.lu@intel.com;
> beilei.xing@intel.com; bernard.iremonger@intel.com; Ori Kam
> <orika@nvidia.com>; NBU-Contact-Thomas Monjalon
> <thomas@monjalon.net>; Raslan Darawsheh <rasland@nvidia.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v2] app/testpmd: fix testpmd packets dump
> overlapping
> 
> On 11/14/2020 12:01 PM, Jiawei Wang wrote:
> > When testpmd enabled the verbosity for the received packets, if two
> > packets was received at the same time, for example, sampling packet
> > and normal packet, the dump output of these packets may be overlapping
> > due to multiple core handled the multiple queues simultaneously.
> >
> > The patch uses one string buffer that collects all the packet dump
> > output into this buffer and then printout it at last, that guarantee
> > to printout separately the dump output per packet.
> >
> > Fixes: d862c45 ("app/testpmd: move dumping packets to a separate
> > function")
> >
> > Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
> > ---
> > v2:
> > * Print dump output of per packet instead of per burst.
> > * Add the checking for return value of 'snprintf' and exit if required size
> exceed the print buffer size.
> > * Update the log messages.
> > ---
> >   app/test-pmd/util.c | 378
> ++++++++++++++++++++++++++++++++++++++++------------
> >   1 file changed, 295 insertions(+), 83 deletions(-)
> >
> > diff --git a/app/test-pmd/util.c b/app/test-pmd/util.c index
> > 649bf8f..ffae590 100644
> > --- a/app/test-pmd/util.c
> > +++ b/app/test-pmd/util.c
> > @@ -12,15 +12,20 @@
> >   #include <rte_vxlan.h>
> >   #include <rte_ethdev.h>
> >   #include <rte_flow.h>
> > +#include <rte_log.h>
> >
> >   #include "testpmd.h"
> >
> > -static inline void
> > -print_ether_addr(const char *what, const struct rte_ether_addr
> > *eth_addr)
> > +#define MAX_STRING_LEN 8192
> 
> Isn't '8192' too large for a single packet, what do you think for '2048'?
> 
2K is ok for the normal case, here consider the case that registered mbuf dynamic flags names, 
Then total maximum length can reach to   64* RTE_MBUF_DYN_NAMESIZE = 4096
 // char dynf_names[64][RTE_MBUF_DYN_NAMESIZE];
So 2048 is not enough if all dynf_names be configured as maximum length of dyn_names.

How about the 5K? I think should be enough for now.
> <...>
> 
> > @@ -93,95 +103,269 @@
> >   		is_encapsulation = RTE_ETH_IS_TUNNEL_PKT(packet_type);
> >   		ret = rte_flow_get_restore_info(port_id, mb, &info, &error);
> >   		if (!ret) {
> > -			printf("restore info:");
> > +			cur_len += snprintf(print_buf + cur_len,
> > +					    buf_size - cur_len,
> > +					    "restore info:");
> 
> What do you think having a macro like below to simplfy the code:
> 
>   #define FOO(buf, buf_size, cur_len, ...) \
>   do { \
>          if (cur_len >= buf_size) break; \
>          cur_len += snprintf(buf + cur_len, buf_size - cur_len, __VA_ARGS__); \
>   } while (0)
> 
> It can be used as:
>   FOO(print_buf, buf_size, cur_len, "restore info:");
> 
Agree, will move these common code into a MARCO, 
I will use the  "MKDUMPSTR" as MARCO name,  means that  making a dump string buffer.

> > +			if (cur_len >= buf_size)
> > +				goto error;
> 
> This 'goto' goes out of the loop, not sure about breking the loop and not
> processing all packets if buffer is out of space for one of the packets.
> Anyway if you switch to macro above, the 'goto' is removed completely.
> 
Use 'break' only break the do{} while and continue to following processing, but won't filled anymore into printbuf since it will break firstly in the MARCO checking.
Or could use 'goto lable' instead 'break' in the marco?
> <...>
> 
> > +		if (cur_len >= buf_size)
> > +			goto error;
> > +		TESTPMD_LOG(INFO, "%s", print_buf);
> 
> Using 'TESTPMD_LOG' appends "testpmd: " at the beggining of the each line,
> for this case it is noise I think, what do you think turning back to printf() as
> done originally?
> 
ok, will use the printf.
> > +		cur_len = 0;
> >   	}
> > +	return;
> > +error:
> > +	TESTPMD_LOG(INFO, "%s the output was truncated ...\n", print_buf);
> 
> What do you think having something shorter to notify the truncation, I think
> some special chars can work better, something like "...", "@@", "-->", "???" ?
> 
ok, I will use simple chars  for truncated case like below:
		if (cur_len >= buf_size)
			printf("%s ...\n", print_buf);
	
> >   }
> >
> >   uint16_t
> >

Thanks for your comments, I will do the changes and send V3 patch.

Thanks.
Jonny