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amd64: reduce VM_KMEM_SIZE_SCALE to 1 allowing kernel to use more memory

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KVA space is abundant on amd64, so there is no reason to limit kernel
map size to a fraction of available physical memory.  In fact, it could
be larger than physical memory.

This should help with memory auto-tuning for ZFS and shouldn't affect
other workloads.
This should reduce number of circumstances for "kmem_map too small"
panics, but probably won't eliminate them entirely due to potential kmem
fragmentation.

In fact, you might want/need to limit maximum ARC size after this commit
if you need to resrve more memory for applications.

This change was discussed on arch@ and nobody said "don't do it".

MFC after:	6 weeks
This commit is contained in:
Andriy Gapon 2010-09-17 07:36:32 +00:00
parent 9d5eb9aa5d
commit 0b750af1b1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=212784
1 changed files with 1 additions and 1 deletions
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2
sys/amd64/include/vmparam.h
View File

@ -205,7 +205,7 @@
* is the total KVA space allocated for kmem_map.
*/
#ifndef VM_KMEM_SIZE_SCALE
#define VM_KMEM_SIZE_SCALE (3)
#define VM_KMEM_SIZE_SCALE (1)
#endif
/*