pkg/46529: ntfs-3g appears to be rate-limited

[agrier%poofygoof.com@localhost]

>Number:         46529
>Category:       pkg
>Synopsis:       ntfs-3g appears to be rate-limited
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Jun 03 06:15:01 +0000 2012
>Originator:     agrier%poofygoof.com@localhost
>Release:        NetBSD 5.1_STABLE
>Organization:
  Aaron J. Grier | "Not your ordinary poofy goof." | 
agrier%poofygoof.com@localhost
>Environment:
System: NetBSD pythagoras.poofy.goof.com 5.1_STABLE NetBSD 5.1_STABLE (GENERIC) 
#0: Wed Jan 12 03:35:24 PST 2011 
agrier%fourier.poofy.goof.com@localhost:/var/obj/amd64/usr/src/sys/arch/amd64/compile/GENERIC
 amd64
Architecture: x86_64
Machine: amd64
>Description:
copying files with ntfs-3g appears to be limited to 2.5MB/s.
copying files from the same device under Linux (which also uses ntfs-3g)
yields > 20MB/s.

pythagoras$ pkg_info -e fuse-ntfs  
fuse-ntfs-3g-1.1120

ehci0 at pci0 dev 18 function 2: vendor 0x1002 product 0x4396 (rev. 0x00)
ehci0: interrupting at ioapic0 pin 17
ehci0: dropped intr workaround enabled
ehci0: BIOS has given up ownership
ehci0: EHCI version 1.0
ehci0: companion controllers, 3 ports each: ohci0 ohci1
...
usb2 at ehci0: USB revision 2.0
...
uhub2 at usb2: vendor 0x1002 EHCI root hub, class 9/0, rev 2.00/1.00, addr 1
uhub2: 6 ports with 6 removable, self powered
...
umass1 at uhub2 port 4 configuration 1 interface 0
umass1: Seagate FreeAgentDesktop, rev 2.00/0.00, addr 3
umass1: using SCSI over Bulk-Only
scsibus1 at umass1: 2 targets, 1 lun per target
sd1 at scsibus1 target 0 lun 0: <Seagate, FreeAgentDesktop, 100D> disk fixed
sd1: fabricating a geometry
sd1: 465 GB, 476940 cyl, 64 head, 32 sec, 512 bytes/sect x 976773168 sectors
sd1: fabricating a geometry

the drive has power savings mode disabled.

>How-To-Repeat:
install ntfs-3g from pkgsrc.
attach NTFS drive to USB.
ntfs-3g /dev/sd1e /disk/media -o ro,uid=100,gid=100,umask=222
do some rsyncing or dding to get speed statistics
>Fix:
my current workaround is to perform NTFS copies from a Linux machine to my
NetBSD file server over the LAN, which puts a 100mbit limit on the copy
(~9MB/s).  this is slower than I observe natively under Linux, but faster than
accessing the drive when directly connected under NetBSD.

>Unformatted: