Installation guide

5.6.1.13 Maximum Number of Callouts
The maxcallouts keyword is based on the maxusers keyword and defines
the maximum number of callouts on the system. It is used to size the
kernel’s callout table. The default number of callouts is determined
automatically based on the value of the maxusers keyword and other
system parameters. Use of the default maxcallouts definition is strongly
recommended.
In the unlikely event that the default value of maxcallouts is not large
enough, your system will panic with a "timeout table overflow" message. To
override the default number of callouts, use the following syntax to add the
maxcallouts keyword to your configuration file:
maxcallouts
[ number]
To determine the correct value for number , you need to understand the
maxcallouts sizing algorithm and to find the current number of callouts.
To examine the sizing algorithm, edit the /usr/sys/conf/param.c file.
Search for the string MAXCALLOUTS, and print the next several lines. You
will notice the algorithm differs for a realtime kernel. To determine the
current number of callouts, enter the following commands:
# dbx -k /vmunix
(dbx) p ncallout
1316
(dbx) q
5.6.1.14 File System Metadata Cache Size
Tru64 UNIX utilizes a unified buffer cache (UBC). The UBC enables
physical memory to be shared between the file system and virtual memory.
The Advanced File System (AdvFS) uses UBC. However, the file system
code that deals with the UNIX File System (UFS) metadata (including
directories, indirect blocks, and inodes) uses the traditional BSD buffer
cache.
The bufcache keyword defines the size of the kernel’s metadata cache.
The value for bufcache is the percentage of the system’s physical memory
that is allocated for the metadata cache. The default metadata cache
memory allocation is 3% of physical memory.
Note that any additional memory that you allocate to the metadata cache is
taken away from the rest of the system. This means that the memory is not
available to the UBC that caches file data and virtual memory data and is
involved in running processes. If you allocate too much memory to the
metadata cache, system performance may decline.
Configuring the Kernel 5–45