From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tom Barbette <barbette@kth.se>
Subject: Which counters are set by rte_eth_stats_get
Date: Fri, 9 Nov 2018 08:28:46 +0000
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Cc: Thomas Monjalon <thomas@monjalon.net>, Ferruh Yigit
 <ferruh.yigit@intel.com>, Andrew Rybchenko <arybchenko@solarflare.com>
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Hi ethdev maintainers,


Support of drivers for the fields in rte_eth_stats is a bit random, and nev=
er mentioned in the doc. A quick survey showed me :


ipackets : implemented by all drivers
ibytes : all except null, ring
ierror : all except af_packet, ark, avf, axgbe, fm10k, kni, null, pcap, rin=
g, szedata2, vhost
imissed : *only* af_packet, avp, axgbe, fm10k, kni, liquidio, mlx4, mlx5, n=
ull, pcap, ring, szedata2, tap, vhost, virtio
rx_nombuf : *only* bnx2x,bnxt,bonding,ena,enic,failsafe,mlx4,mlx5,netvsc,nf=
p,qede,szedata2,tap,virtio

With no way to know if we can rely on the value or not, as a DPDK user pov.=
 The only way to know if we can rely on a given counter is to grep the driv=
er code. Except if I missed something?

Also the doc of rte_eth_stats_get only mention io packets, bytes and errors=
. Not the other fields, and the way it is written let the reader think it i=
s always supported if the function does not return 0.

I can update the doc to reflect the state of things. But maybe we could mak=
e that function return a bitmask which tells which counter has been set. Bu=
t that would break the ABI... We could also have the bitmask set through a =
passed pointer, so it does not break code checking the return value is 0. O=
r maybe have the bitmask elsewhere, like for the offloads? Which fields are=
 supported is probably a constant. So that may make more sense.

If you give me directions, I can propose a patch.

Cheers,
Tom