tree a039e77970aa5ed39902dfeeed41df2db3f7f2c4
parent ecb80c6a490863af569853eea2a925f97e9e856a
author Mike Miller <mike.miller@hp.com> 1204626315 +0100
committer Jens Axboe <jens.axboe@oracle.com> 1204626523 +0100

cciss: remove READ_AHEAD define and use block layer defaults

This patch removes the #define READ_AHEAD 1024 from the driver and uses the
block layer defaults, instead. We have found that under certain workloads
the setting can cause a disk connected to the e200 controller to go offline.
If the disk hiccups the link may try to downshift but the controller is
never notified that the link successfully completed the renegotiation.
We've also found that performance using the block layer default of 32 pages
was on par with the 1024 setting. We tried setting it to zero at one time
based on info from our firmware guys but that killed performance. Turns out
we were talking about 2 different read ahead settings.
Please consider this for inclusion.

Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>