02-06-2014
Quote:
Originally Posted by
dzodzo
How can i tell what will be the maximum kernel memory? We measured this after reboot and starting the applications, kernel took only 2 GB but during 4 months it gradually grew to 13 GB. What would happen if i configured applications to take let's say 60 GB of memory. Will AIX handle that and live with 4 GB for kernel or will it start trashing until reboot is necessary?
I do not know a formula too calculate the minimum for kernel memory.
As you said the memory usage will grow with time and usage (mbufs, inode cache, jfs bufstructs, etc.) and the increase depends on the maximum installed memory. The Kernel used pinned memory (vmstat -v) and if your application with 60GB also used pinned memory, your server will crash/panic if there are no more memory which can be pinned. That happened to us after two weeks with a wrong Informix memory configuration. The other way the server starts to swap out (paging space) and the performance slows down.
Regards
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LEARN ABOUT REDHAT
elvtune
ELVTUNE(8) System Manager's Manual ELVTUNE(8)
NAME
elvtune - I/O elevator tuner
SYNOPSIS
elvtune [ -r r_lat ] [ -w w_lat ] [ -b b_max ] /dev/blkdev1 [ /dev/blkdev2 ... ]
elvtune -h
elvtune -v
DESCRIPTION
elvtune allows to tune the I/O elevator per blockdevice queue basis. The tuning can be safely done at runtime. Tuning the elevator means
being able to change disk performance and interactiveness. In the output of elvtune the address of the queue tuned will be shown and it can
be considered as a queue ID. For example multiple partitions in the same harddisk will share the same queue and so tuning one partition
will be like tuning the whole HD.
OPTIONS
-r r_lat
set the max latency that the I/O scheduler will provide on each read.
-w w_lat
set the max latency that the I/O scheduler will provide on each write.
-b b_max
max coalescing factor allowed on writes when there are reads pending in the queue.
-h help.
-v version.
NOTE
Actually the only fields tunable are those relative to the IO scheduler. It's not possible to select a one-way or two-way elevator yet.
For logical blockdevices like LVM the tuning has to be done on the physical devices. Tuning the queue of the LVM logical device is useless.
RETURN VALUE
0 on success and 1 on failure.
HISTORY
Ioctls for tuning elevator behaviour were added in Linux 2.3.99-pre1.
AUTHORS
Andrea Arcangeli <andrea@suse.de> SuSE
Version 1.0 14 March 2000 ELVTUNE(8)