[PATCH 1/3] ethtool: Support ETHTOOL_GSTATS2 command.
greearb at candelatech.com
Thu Apr 19 08:25:41 PDT 2018
On 04/18/2018 11:38 PM, Johannes Berg wrote:
> On Wed, 2018-04-18 at 14:51 -0700, Ben Greear wrote:
>>> It'd be pretty hard to know which flags are firmware stats?
>> Yes, it is, but ethtool stats are difficult to understand in a generic
>> manner anyway, so someone using them is already likely aware of low-level
>> details of the driver(s) they are using.
> Right. Come to think of it though,
>> + * @get_ethtool_stats2: Return extended statistics about the device.
>> + * This is only useful if the device maintains statistics not
>> + * included in &struct rtnl_link_stats64.
>> + * Takes a flags argument: 0 means all (same as get_ethtool_stats),
>> + * 0x1 (ETHTOOL_GS2_SKIP_FW) means skip firmware stats.
>> + * Other flags are reserved for now.
>> + * Same number of stats will be returned, but some of them might
>> + * not be as accurate/refreshed. This is to allow not querying
>> + * firmware or other expensive-to-read stats, for instance.
> "skip" vs. "don't refresh" is a bit ambiguous - I'd argue better to
> either really skip and not return the non-refreshed ones (also helps
> with the identifying), or rename the flag.
In order to efficiently parse lots of stats over and over again, I probe
the stat names once on startup, map them to the variable I am trying to use
(since different drivers may have different names for the same basic stat),
and then I store the stat index.
On subsequent stat reads, I just grab stats and go right to the index to
store the stat.
If the stats indexes change, that will complicate my logic quite a bit.
Maybe the flag could be called: ETHTOOL_GS2_NO_REFRESH_FW ?
> Also, wrt. the rest of the patch, I'd argue that it'd be worthwhile to
> write the spatch and just add the flags argument to "get_ethtool_stats"
> instead of adding a separate method - internally to the kernel it's not
> that hard to change.
Maybe this could be in followup patches? It's going to touch a lot of files,
and might be hell to get merged all at once, and I've never used spatch, so
just maybe someone else will volunteer that part :)
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc http://www.candelatech.com
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