Hi
The patch 1c30844d2dfe272d58c8fc000960b835d13aa2ac ("mm: reclaim small
amounts of memory when an external fragmentation event occurs") breaks
memory management on parisc.
I have a parisc machine with 7GiB RAM, the chipset maps the physical
memory to three zones:
0) Start 0x0000000000000000 End 0x000000003fffffff Size 1024 MB
1) Start 0x0000000100000000 End 0x00000001bfdfffff Size 3070 MB
2) Start 0x0000004040000000 End 0x00000040ffffffff Size 3072 MB
(but it is not NUMA)
With the patch 1c30844d2, the kernel will incorrectly reclaim the first
zone when it fills up, ignoring the fact that there are two completely
free zones. Basiscally, it limits cache size to 1GiB.
For example, if I run:
# dd if=/dev/sda of=/dev/null bs=1M count=2048
- with the proper kernel, there should be "Buffers - 2GiB" when this
command finishes. With the patch 1c30844d2, buffers will consume just 1GiB
or slightly more, because the kernel was incorrectly reclaiming them.
Mikulas
