Re: [PATCH] Shrinks sizeof(files_struct) and better layout

[Folkert van Heusden <folkert@vanheusden.com>]

> >>2) Reduces the size of (files_struct), using a special 32 bits (or 64bits)
> >>embedded_fd_set, instead of a 1024 bits fd_set for the close_on_exec_init 
> >>and
> >>open_fds_init fields. This save some ram (248 bytes per task)
> >>as most tasks dont open more than 32 files.
> >How do you know, have you done some empirical testing?
> 20 years working on Unix/linux machines yes :)
> Just try this script on your linux machines :
> for f in /proc/*/fd; do ls $f|wc -l;done
> more than 95% of tasks have less than 32 concurrent files opened.

0 root@muur:/home/folkert# for f in /proc/*/fd; do ls $f|wc -l;done | awk '{TOT+=$1; N++;} END{ print TOT / N, N; }'
13.7079 291

So on my system (running 291 processes (postfix, mysql, apache,
asterisk, spamassassin, clamav) it is on average 13.7 filehandles.
On an idle veritas netbackup server (130 processes): 4
On a system running 4 vmware systems (137 processes): 16
On a heavily used mailserver (130 processes, sendmail and MailScanner
package): 6,6


Folkert van Heusden

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