VM_BCACHE_SIZE_MAX on i386

[David Wolfskill]

On Sat, Mar 23, 2013 at 11:10:01PM +0200, Konstantin Belousov wrote:
> ...
> The resolution I propose is to change the VM_BCACHE_SIZE_MAX on i386
> !PAE case, to make it equal to the exact max size of the buffer cache.
> Note that maxbcache can be tuned from the loader prompt, so the effect
> of the change would be only on the i386 machines with tuned buffer
> cache.
> 
> Also, the patch doubles the size of the transient map to 1/5 of the
> max buffer cache. This gives 180 parallel remapped i/os in flight,
> since I consider the re-caclulated 90 i/os too small even for i386.
> 
> The patch was tested by dwh, please comment. I intend to commit it in
> several days.
> 
> http://people.freebsd.org/~kib/misc/i386_maxbcache.1.patch

For those interested, the testing involved (after new kernel built
@r248612M with the patch) running X with the nvidia driver while
performing a "make -j 4 buildworld kernel ... installworld" while I was
doing my usual Friday afternoon work-related "stuff" on the machine
(which mostly involved running xterms executing on various remote
machines, but displaying on the laptop).

Subsequently (as in "this morning"), I did my usual daily update of
(head) /usr/src & rebuilt -- again while running X with nvidia (as I
normally do).  That slice is now running FreeBSD 10.0-CURRENT #846
r248645M/248646: Sat Mar 23 06:24:53 PDT 2013.

If I encounter issues, I fully expect to "squawk" about it -- most
likely, in current at .  That said: no issues since applying the patch.  :-)

Peace,
david   (aka dhw at freebsd.org)
-- 
David H. Wolfskill				david at catwhisker.org
Taliban: Evil men with guns afraid of truth from a 14-year old girl.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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