Performance of SheevaPlug on 8-stable

[Steve Woodford]

On Monday 22 March 2010 16:26:09 Mark Tinguely wrote:

> This situation could have been around for a while. Before FreeBSD
> 8.0, the kernel maps did not have pv_entrys, and the cache fix
> routines did not count them and we did not even know these
> user/kernel overlap existed.

During development of the NetBSD/arm32 pmap (which FreeBSD now uses), I 
noticed the same problem. The root cause was down in NetBSD's unified 
buffer cache code, which mapped FS buffers writable by default.

The fix can be found by looking for PMAP_CACHE_VIVT in NetBSD's 
sys/uvm/*

While FreeBSD doesn't use UVM, it might be useful to check if your VM 
code needs a similar fix.

Steve