Limits revisited

I feel obliged to point out that this blog post is roughly 5 years and 1 month old. People change, opinions evolve. In just a few years, vast technological landscapes can shift. And don't get me started on config files. Please consider this text in the context of its time.

There were more limits changed in regard to open files as well. The change took place in SRU27.

rlim_fd_cur has been increased from 256 pre-SRU27 to 4095 now.
rlim_fd_max has been decreased from 65536 to 65535.
rlim_fd_sys which is the source of the system-wide max-file-descriptor setting has been made dependent on the memory size in its default. To cite the documentation:

Starting with Oracle Solaris 11.4 SRU 27, calculated based on physmem to be approximately 65K per gigabyte of memory. The value is rounded up to the nearest value of (2^N)-1.

The change in regard to rlim_fd_sys can be shown best with a short prctl -i process $$. Please have a look at the last line. First the output of a pre-SRU 27 system.

process.max-file-descriptor
        basic             256       -   deny                                 -
        privileged      65,5K       -   deny                                 -
        system          2,15G     max   deny

Now let’s do this again on a SRU30 system:

process.max-file-descriptor
        basic           4,09K       -   deny                                 -
        privileged      65,5K       -   deny                                 -
        system           131K     max   deny

For more information please consult the Tunable Parameters Reference Guide’s chapter about general I/O parameters.