On Wed, Jun 10, 2026 at 10:06 PM Keith Busch <[email protected]> wrote: > > 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. That's correct, it's the atomic operation accounting overhead.
Thanks, Sumit
smime.p7s
Description: S/MIME Cryptographic Signature
