[openssl-users] OpenSSL s_time output meaning

Michael Wojcik Michael.Wojcik at microfocus.com
Thu Jun 30 19:00:14 UTC 2016

> From: openssl-users [mailto:openssl-users-bounces at openssl.org] On Behalf
> Of danigrosu
> Sent: Tuesday, June 28, 2016 22:57
> To: openssl-users at openssl.org
> Subject: [openssl-users] OpenSSL s_time output meaning
> Using the `$ openssl s_time -connect localhost:443 -new -time 30` command
> gives this output:
> No CIPHER specified
> Collecting connection statistics for 30 seconds
> ********** etc.
> 8102 connections in 12.65s; 640.47 connections/user sec, bytes read 0
> 8102 connections in 31 real seconds, 0 bytes read per connection
> What is the difference between 8102 connections in 12.65s and 8102
> connections in 31 real seconds ?

Use the source, Luke.

Yes, the output is confusing; "real seconds" is not a particularly meaningful term. (What, the imaginary part is zero?) The value that's displayed there is the "wall-clock time" elapsed between the start of the test and when the report is produced. It's the sum of the time specified by -time (or the 30s default) plus the overhead that's not counted while timing actual OpenSSL operations, rounded to 1-second granularity.

The 12.65s in the first line is the value of "totalTime", which is the accumulator for the timer the openssl command uses for timing the test. The s_time command starts this timer before the connection loop and stops it after the loop. The timer (in this case) counts only "user" time, that is time the process spends in user mode; that's why that line says "user sec".

So this is telling you that your system uses about 1.5ms of user-mode CPU time per connection, and that it was able to make about 270 connections per second.

I'm not sure what use that information might be to you, since you haven't told us why you're running s_time in the first place.

Michael Wojcik
Technology Specialist, Micro Focus

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