will do some tests in weekend
On Sun, 11 May 2014, Francois Tigeot wrote:
On Sun, May 11, 2014 at 12:19:57PM +0200, Wojciech Puchar wrote:
How to turn in on in dragonfly? i mean setting maximum disk I/O to 2 or
4MB - same as i do in FreeBSD to get large performance gain on big files.
in FreeBSD
options MAXPHYS=2097152 (or twice that)
options DFLTPHYS=262144
You could try changing the value of MAXPHYS in sys/cpu/${ARCH}/include/param.h
MAXPHYS, the maximum allowed I/O size is still capped at 64KB (i386) or 128KB
(x86_64/amd64) by default.
I experimented for a while with the ahci driver; bigger values helped to
increase linear (dd) performance by up to 20% with fast SSDs but it was unclear
at the time if it would have improved regular filesystem operations.
Even though all storage drivers compile fine with bigger MAXPHYS values it's
also possible some will have issues at runtime.
--
Francois Tigeot
