Re: [PATCH 1/2] Convert target drivers to use sbitmap

On 5/15/18 10:11 AM, Jens Axboe wrote:

On 5/15/18 10:00 AM, Matthew Wilcox wrote:

quoted

From: Matthew Wilcox <redacted>

The sbitmap and the percpu_ida perform essentially the same task,
allocating tags for commands.  Since the sbitmap is more used than
the percpu_ida, convert the percpu_ida users to the sbitmap API.

It should also be the same performance as percpu_ida in light use, and
performs much better at > 50% utilization of the tag space. I think
that's better justification than "more used than".

Had to search long and hard for the perf numbers I did for percpu_ida
on higher utilization, but here it is:

https://lkml.org/lkml/2014/4/22/553

-- 
Jens Axboe