Jonathan Edwards wrote:

On May 15, 2007, at 13:13, Jürgen Keil wrote:

Would you mind also doing:

ptime dd if=/dev/dsk/c2t1d0 of=/dev/null bs=128k count=10000

to see the raw performance of underlying hardware.

This dd command is reading from the block device,
which might cache dataand probably splits requests
into "maxphys" pieces (which happens to be 56K on an
x86 box).

to increase this to say 8MB, add the following to /etc/system:

set maxphys=0x800000

and you'll probably want to increase sd_max_xfer_size as
well (should be 256K on x86/x64) .. add the following to
/kernel/drv/sd.conf:

sd_max_xfer_size=0x800000;

then reboot to get the kernel and sd tunings to take.

---
.je

btw - the defaults on sparc:
maxphys = 128K
ssd_max_xfer_size = maxphys
sd_max_xfer_size = maxphys

Maybe we should file a bug to increase the max transfer request sizes?
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