]> git.baikalelectronics.ru Git - kernel.git/commit
s390/dasd: mark DASD devices as non rotational
authorChristian Borntraeger <borntraeger@de.ibm.com>
Fri, 4 Sep 2015 11:52:44 +0000 (13:52 +0200)
committerMartin Schwidefsky <schwidefsky@de.ibm.com>
Wed, 14 Oct 2015 12:32:00 +0000 (14:32 +0200)
commit612fe7255c472803e6019be8ba81b24ac886a9de
treefb7f6013afc7f6f7bf72e3bca44dd30183374747
parent18df048b1f4add8781790cb982b1c15967cfb7f5
s390/dasd: mark DASD devices as non rotational

We were able to reduce the CPU overhead of big paging scenarios
when announcing our paging disks as non-rotational.
Almost all dasd devices are implemented in storage servers with
cache, raid, striping and lots of magic. There is no point in
optimizing the disk schedulers and swap code for a single platter
moving arm rotational disks. Given the complexity of the setup
and the fact that this change is mostly to disable the additional
overhead in swap code, lets keep the other functionality unchanged
and do not disable the this device as entropy source - unlike other
non-rotational devices.

Suggested-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
drivers/s390/block/dasd.c