David wrote:
> what does block I/O priority support mean, what does it do
File system code can set an I/O elevator priority to read and write requests
that it sends to block device driver. It is up to the disk I/O elevator code
code to schedule high priority requests to be processed earlier than low
priority requests.
I added one line of code to loop that copies original priority of read and
write requests to the request that loop sends to underlying device.
read or write request here, with some I/O priority
|
v
file system ---> loop ---> IDE or SCSI driver
^
|
same I/O priority copied here
But... I looked at the code again today, and noticed that the bitfield of
the structure where priority is stored, is already copied some source code
lines earlier. Me adding code that sets it again was silly. That second
unnecessary copy doesn't do any harm other than waste few processor cycles,
and embarrass me.
> and does it make the drives data more secure?
No.
> Also, how is it used/activated?
Quick recursive grep of mainline 2.6.13 kernel source does not show any code
that that uses bio_set_prio() to set I/O priority to non-default value. It
is not of much use today.
--
Jari Ruusu 1024R/3A220F51 5B 4B F9 BB D3 3F 52 E9 DB 1D EB E3 24 0E A9 DD
-
Linux-crypto: cryptography in and on the Linux system
Archive: http://mail.nl.linux.org/linux-crypto/
