Hi there,
While running performance benchmarks for the 5.15.196 LTS tags , it was observed that several regressions across different benchmarks is being introduced when compared to the previous 5.15.193 kernel tag. Running an automated bisect on both of them narrowed down the culprit commit to: - 5666bcc3c00f7 Revert "cpuidle: menu: Avoid discarding useful information" for 5.15
Regressions on 5.15.196 include: -9.3% : Phoronix pts/sqlite using 2 processes on OnPrem X6-2 -6.3% : Phoronix system/sqlite on OnPrem X6-2 -18% : rds-stress -M 1 (readonly rdma-mode) metrics with 1 depth & 1 thread & 1M buffer size on OnPrem X6-2 -4 -> -8% : rds-stress -M 2 (writeonly rdma-mode) metrics with 1 depth & 1 thread & 1M buffer size on OnPrem X6-2 Up to -30% : Some Netpipe metrics on OnPrem X5-2
The culprit commits' messages mention that these reverts were done due to performance regressions introduced in Intel Jasper Lake systems but this revert is causing issues in other systems unfortunately. I wanted to know the maintainers' opinion on how we should proceed in order to fix this. If we reapply it'll bring back the previous regressions on Jasper Lake systems and if we don't revert it then it's stuck with current regressions. If this problem has been reported before and a fix is in the works then please let me know I shall follow developments to that mail thread.
Thanks & Regards, Harshvardhan