> On Mar 23, 2016, at 2:50 PM, Uma Krishnan <ukrishn@xxxxxxxxxxxxxxxxxx> wrote: > > From: "Manoj N. Kumar" <manoj@xxxxxxxxxxxxxxxxxx> > > While profiling the cxlflash_queuecommand() path under a heavy load it > was found that number of retries to find cmd_room was fairly high. > > There are two problems with the current back-off: > a) It starts with a udelay of 0 > b) It backs-off linearly > > 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. > > 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). > > Signed-off-by: Manoj N. Kumar <manoj@xxxxxxxxxxxxxxxxxx> Acked-by: Matthew R. Ochs <mrochs@xxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
