On Mar 23, 2016, at 2:50 PM, Uma Krishnan [off-list ref] =

wrote:

=20
From: "Manoj N. Kumar" <redacted>
=20
While profiling the cxlflash_queuecommand() path under a heavy load it
was found that number of retries to find cmd_room was fairly high.
=20
There are two problems with the current back-off:
a) It starts with a udelay of 0
b) It backs-off linearly
=20
Tried several approaches (a higher multiple 10*n, 100*n, as well as =

n^2,

2^n) and found that the exponential back-off(2^n) approach had the =

least

overall cost. Cost as being defined as overall time spent waiting.
=20
The fix is to change the linear back-off to an exponential back-off.
This solution also takes care of the problem with the initial
delay (starts with 1 usec).
=20
Signed-off-by: Manoj N. Kumar <redacted>

Acked-by: Matthew R. Ochs <redacted>