On Thu, Sep 26, 2013 at 08:50:15PM +0200, Fabien COELHO wrote: > > Patch (4): Redefine "latency" as reported by pgbench and report "lag" more. > > Here is a first partial patch, which focusses on measuring latency > and reporting the measure under --progress.
This patch contains the features pertaining to both hypothetical patches (3) and (4), not just (4) like I requested. The sum of the squares of the latencies wraps after 2^63/(10^12 * avg_latency * nclients) seconds. That's unlikely to come up with the ordinary pgbench script, but one can reach it in a few hours when benchmarking a command that runs for many seconds. If we care, we can track the figure as a double. I merely added a comment about it. I restored applicable parts of your update to the --progress documentation from pgbench-measurements-v5.patch. The patch made output like this: progress: 7.2 s, 1.7 tps, 205.225 stddev 3.484 ms lat, 45.472 ms lag I read that as five facts: 7.2 s 1.7 tps 205.225 stddev 3.484 ms lat 45.472 ms lag That was a wrong reading; 205.225 is the latency average and 3.484 is the latency standard deviation. Let's be consistent about the placement of labels relative to their figures. Upthread, had you proposed this format: progress: 36.0 s, 115.2 tps, lat avg 9.678 ms stddev 1.792, lag 0.143 ms I switched to that, except that I removed the word "avg" to save horizontal space and since lag is also an average though not labelled as such. > + printf("latency average: %.3f ms\n", > + 1000.0 * duration / normal_xacts); I incorporated the "nclients" factor needed here. Committed with those changes. -- Noah Misch EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers