sysctl maxfiles

Miroslav Lachman 000.fbsd at
Sat Sep 27 22:44:32 UTC 2008

Peter Jeremy wrote:
> On 2008-Sep-27 22:14:09 +0200, Miroslav Lachman <000.fbsd at> wrote:
>>root at roxy ~/# fstat -u www | wc -l
>>    9931
>>root at roxy ~/# fstat -u root | wc -l
>>     718
>>root at roxy ~/# fstat | grep httpd | wc -l
>>    6379
>>root at roxy ~/# fstat | grep httpd | wc -l
>>    6002
>>root at roxy ~/# fstat -u www | wc -l
>>    4691
>>root at roxy ~/# sysctl kern.openfiles
>>kern.openfiles: 846
> kern.openfiles reflects the total number of open file structures
> within the kernel, whereas fstat (and lsof) report both open files
> and vnodes associated with each process.  The differences are
> 1) File structures are shared via fork() etc so the same file structure
>    can be reported multiple times.
> 2) fstat reports executable name, working directory and root
> Open files in fstat can be detected because they have numeric values
> (possibly with a '*' appended) in the FD column.  Unfortunately, there
> doesn't appear to be any easy way to detect shared file structures
> (for inode-based files) using either fstat or lsof.
> In the case of apache, there are at least 6 file structures shared
> by each httpd process (and it looks like it might be about 15).

Thank you for your explanation. (Jeremy Chadwick, Oliver Fromme, Peter 
Now it makes sense to me.

Miroslav Lachmanx

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