On Fri, Mar 22, 2013 at 03:24:15PM -0700, Andy Zhou wrote:
> This patch adds more flow related stats to the output of
> "ovs-appctl dpif/show". Specifically, the follow information
> are added per ofproto:
>
> - Max flow table size
> - Average flow table size
> - Average flow table add rate
> - Average flow table delete rate
> - Average flow entry life in milliseconds
>
> Feature #15366
>
> Signed-off-by: Andy Zhou <az...@nicira.com>
The word 'subfacet' is misspelled in member 'total_sufacet_life_span'.
I found the new members of struct ofproto_dpif a little hard to
understand. How about something like this:
/* Subfacet statistics.
*
* These keep track of the total number of subfacets added and deleted and flow
* life span. They are useful for computing the flow rates stats exposed via
* "ovs-appctl dpif/show". The goal is to learn about traffic patterns in ways
* that we can use later to improve Open vSwitch performance in new siutations.
*/
long long int created; /* Time ofproto_dpif was created. */
unsigned int max_n_subfacet; /* Maximum number of flows. */
/* The average number of subfacets... */
struct avg_subfacet_rates hourly; /* ...over the last hour. */
struct avg_subfacet_rates daily; /* ...over the last day. */
long long int last_minute; /* Last time 'hourly' was updated. */
/* Number of subfacets added or deleted since 'last_minute'. */
unsigned int subfacet_add_count;
unsigned int subfacet_del_count;
/* Number of subfacets added or deleted from 'created' to 'last_minute'. */
unsigned long long int total_subfacet_add_count;
unsigned long long int total_subfacet_del_count;
/* Sum of the number of milliseconds that each subfacet existed, over the
* subfacets that have been added and then later deleted. */
unsigned long long int total_subfacet_life_span;
/* Incremented by the number of currently existing subfacets, each time we
* pull statistics from the kernel. */
unsigned long long int total_subfacet_count;
I think there is an issue with 'total_subfacet_count'. This is
incremented approximately once per second, but avg_subfacet_count() only
divides it by 60*minutes, where minutes is the whole of minutes elapsed.
I think that this means that avg_subfacet_count() will tend to increase
over the course of a minute and then drop back down as the next minute
ticks over. Also, update_stats() updates total_subfacet_count but that
function may run more often than once a second (if there are many
subfacets) or less often than once a second (if OVS doesn't get
scheduled on time) so I think that we ought to count the number of
updates instead of assuming that there are exactly 60 per minute.
Thanks,
Ben.
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