https://github.com/torvalds/linux
Revision a7e69ddb10f72f17556bfe99259ecb10cbcb4b5c authored by Mark on 19 August 2014, 20:45:22 UTC, committed by Greg Kroah-Hartman on 25 August 2014, 17:46:11 UTC
The uSCSI from Newer Technology is a SCSI-USB converter with USB ID 06ca:2003. Like several other SCSI-USB products, it's a Shuttle Technology OEM device. Without a suitable entry in unusual-devs.h, the converter can only access the (single) device with SCSI ID 0. Copying the entry for device 04e6:0002 allows it to work with devices with other SCSI IDs too. There are currently six entries for Shuttle-developed SCSI-USB devices in unusual-devs.h (grep for euscsi): 04e6:0002 Shuttle eUSCSI Bridge USB_SC_DEVICE, USB_PR_DEVICE 04e6:000b Shuttle eUSCSI Bridge USB_SC_SCSI, USB_PR_BULK 04e6:000c Shuttle eUSCSI Bridge USB_SC_SCSI, USB_PR_BULK 050d:0115 Belkin USB SCSI Adaptor USB_SC_SCSI, USB_PR_BULK 07af:0004 Microtech USB-SCSI-DB25 USB_SC_DEVICE, USB_PR_DEVICE 07af:0005 Microtech USB-SCSI-HD50 USB_SC_DEVICE, USB_PR_DEVICE lsusb -v output for the uSCSI lists bInterfaceSubClass 6 SCSI bInterfaceProtocol 80 Bulk (Zip) This patch adds an entry for the uSCSI to unusual_devs.h. Signed-off-by: Mark Knibbs <markk@clara.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 parent 563da3a
Tip revision: a7e69ddb10f72f17556bfe99259ecb10cbcb4b5c authored by Mark on 19 August 2014, 20:45:22 UTC
USB: storage: add quirk for Newer Technology uSCSI SCSI-USB converter
USB: storage: add quirk for Newer Technology uSCSI SCSI-USB converter
Tip revision: a7e69dd
overcommit-accounting
The Linux kernel supports the following overcommit handling modes
0 - Heuristic overcommit handling. Obvious overcommits of
address space are refused. Used for a typical system. It
ensures a seriously wild allocation fails while allowing
overcommit to reduce swap usage. root is allowed to
allocate slightly more memory in this mode. This is the
default.
1 - Always overcommit. Appropriate for some scientific
applications. Classic example is code using sparse arrays
and just relying on the virtual memory consisting almost
entirely of zero pages.
2 - Don't overcommit. The total address space commit
for the system is not permitted to exceed swap + a
configurable amount (default is 50%) of physical RAM.
Depending on the amount you use, in most situations
this means a process will not be killed while accessing
pages but will receive errors on memory allocation as
appropriate.
Useful for applications that want to guarantee their
memory allocations will be available in the future
without having to initialize every page.
The overcommit policy is set via the sysctl `vm.overcommit_memory'.
The overcommit amount can be set via `vm.overcommit_ratio' (percentage)
or `vm.overcommit_kbytes' (absolute value).
The current overcommit limit and amount committed are viewable in
/proc/meminfo as CommitLimit and Committed_AS respectively.
Gotchas
-------
The C language stack growth does an implicit mremap. If you want absolute
guarantees and run close to the edge you MUST mmap your stack for the
largest size you think you will need. For typical stack usage this does
not matter much but it's a corner case if you really really care
In mode 2 the MAP_NORESERVE flag is ignored.
How It Works
------------
The overcommit is based on the following rules
For a file backed map
SHARED or READ-only - 0 cost (the file is the map not swap)
PRIVATE WRITABLE - size of mapping per instance
For an anonymous or /dev/zero map
SHARED - size of mapping
PRIVATE READ-only - 0 cost (but of little use)
PRIVATE WRITABLE - size of mapping per instance
Additional accounting
Pages made writable copies by mmap
shmfs memory drawn from the same pool
Status
------
o We account mmap memory mappings
o We account mprotect changes in commit
o We account mremap changes in size
o We account brk
o We account munmap
o We report the commit status in /proc
o Account and check on fork
o Review stack handling/building on exec
o SHMfs accounting
o Implement actual limit enforcement
To Do
-----
o Account ptrace pages (this is hard)
Computing file changes ...