On Wed, Jun 10, 2026 at 09:16:11PM +0530, Sumit Saxena wrote: > The motivation for this change stems from performance issue we > encountered due to false sharing of the 'nr_active_requests_shared_tags' > counter > on certain CPU architectures. I initially submitted a patch to move that > counter to > its own cache line to avoid conflicts with 'nr_requests' and other hot > fields > (see: > https://patchwork.kernel.org/project/linux-scsi/patch/[email protected]/ > ). > > During the review, Bart shared his work, which eliminates the > counter entirely by removing the fairness throttling. My testing confirmed > that > this approach resolved the performance issues and improved IOPS. > This patch is part of a larger set, and I have reported the cumulative > performance > improvements in the cover letter.
So the problem is just the atomic operation accounting overhead? I previously thought the device just really needed to consume all the tags to hit performance.
