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Wysocki (Intel)" Cc: rafael.j.wysocki@intel.com, Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , frederic@kernel.org, linux-pm@vger.kernel.org, LKML , regressions@lists.linux.dev References: <096b42fa-107f-450d-b3b1-03bcad3f1e04@oracle.com> <5f5cb821-92ae-4539-ae81-a43e33a7ded5@arm.com> <774c3a68-6a6b-4e2e-a347-03e36953b750@arm.com> <0b9b9c3d-8ba0-4329-9504-b9d33c627649@arm.com> Content-Language: en-US, fr-FR Autocrypt: addr=fainelli@broadcom.com; keydata= xsBNBFPAG8ABCAC3EO02urEwipgbUNJ1r6oI2Vr/+uE389lSEShN2PmL3MVnzhViSAtrYxeT M0Txqn1tOWoIc4QUl6Ggqf5KP6FoRkCrgMMTnUAINsINYXK+3OLe7HjP10h2jDRX4Ajs4Ghs JrZOBru6rH0YrgAhr6O5gG7NE1jhly+EsOa2MpwOiXO4DE/YKZGuVe6Bh87WqmILs9KvnNrQ PcycQnYKTVpqE95d4M824M5cuRB6D1GrYovCsjA9uxo22kPdOoQRAu5gBBn3AdtALFyQj9DQ KQuc39/i/Kt6XLZ/RsBc6qLs+p+JnEuPJngTSfWvzGjpx0nkwCMi4yBb+xk7Hki4kEslABEB AAHNKEZsb3JpYW4gRmFpbmVsbGkgPGZhaW5lbGxpQGJyb2FkY29tLmNvbT7CwSQEEAEKAM4X CgABv0jL/n0t8VEFmtDa8j7qERo7AN0gFAAAAAAAFgABa2V5LXVzYWdlLW1hc2tAcGdwLmNv bY4wFIAAAAAAIAAHcHJlZmVycmVkLWVtYWlsLWVuY29kaW5nQHBncC5jb21wZ3BtaW1lCAsJ CAcDAgEKAhkBBReAAAAAGRhsZGFwOi8va2V5cy5icm9hZGNvbS5jb20FGwMAAAADFgIBBR4B AAAABBUICQoWIQTV2SqX55Fc3tfkfGiBMbXEKbxmoAUCZNaBugUJI+Jo+gAKCRCBMbXEKbxm oNb9B/9/GCiZzNiK61IY24a16Cu83Da7ayx8OhpE/LZC7nkUd8Gd5K7lL+yDcC56aFx1EzKp bsug1GFaMsjAPi8QqMHSCly0S4oCaazZZEikCSIidmlxCLKEglcslpqUBQAeC6oArE9xJh7c zpcBgiMRH1ZJpVZZ5xpwnhsIe9RdT7p4BTDcZ2cErc+jUkGg7FApgIDOrV9vjRQ5khF2zKH8 QYDPhpauwl2SHCBRZtVRi9ur5Jy8PnlkhLf1XEf2MsptHJHE+A7twVtJJaFre6gNPQI0y/dh kCTj3bekpjEP//+/qt3bMRWRPle8a4rlyn5MGqN2ewYgCOuGtu0xtxhvIEmYzsBNBFPAG8EB CACsa+9aKnvtPjGAnO1mn1hHKUBxVML2C3HQaDp5iT8Q8A0ab1OS4akj75P8iXYfZOMVA0Lt 65taiFtiPT7pOZ/yc/5WbKhsPE9dwysrvHjHL2gP4q5vZV/RJduwzx8v9KrMZsVZlKbvcvUv gZmjG9gjPSLssTFhJfa7lhUtowFof0fAq3Zy+vsy5OtEe1xs5kiahdPb2DZSegXW7DFg15GF lj+VG9WSRjSUOKk+4PCDdKl8cy0LJs+rW4CzBB2ARsfNGwRfAJHU4Xeki4a3gje1ISEf+TVx qqLQGWqNsZQ6SS7jjELaB/VlTbrsUEGR1XfIn/sqeskSeQwJiFLeQgj3ABEBAAHCwYEEGAEC ASsFAlPAG8IFGwwAAADAXSAEGQEIAAYFAlPAG8EACgkQk2AGqJgvD1UNFQgAlpN5/qGxQARK eUYOkL7KYvZFl3MAnH2VeNTiGFoVzKHOe7LIwmp3eZ6GYvGyoNG8cOKrIPvXDYGdzzfwxVnD SnAE92dv+H05yanSUv/2HBIZa/LhrPmVhXKgD27XhQjOHRg0a7qOvSKx38skBsderAnBZazf Lw9OukSnrxXqW/5pe3mBHTeUkQC8hHUDCngkn95nnLXaBAhKnRfzFqX1iGENYRH3Zgtis7Zv odzZLfWUC6nN8LDyWZmw/U9HPUaYX8qYMP0n039vwh6GFZCqsFCMyOfYrZeS83vkecAwcoVh 8dlHdke0rnZk/VytXtMe1u2uc9dUOr687hA+Z0L5IQAKCRCBMbXEKbxmoLoHCACXeRGHuijO mOkbyOk7x6fkIG1OXcb46kokr2ptDLN0Ky4nQrWp7XBk9ls/9j5W2apKCcTEHONK2312uMUE ryWI9BlqWnawyVL1LtyxLLpwwsXVq5m5sBkSqma2ldqBu2BHXZg6jntF5vzcXkqG3DCJZ2hO ldFPH+czRwe2OOsiY42E/w7NUyaN6b8Hrw1j77+q3QXldOw/bON361EusWHdbhcRwu3WWFiY 2ZslH+Xr69VtYAoMC1xtDxIvZ96ps9ZXpUPJUqHJr8QSrTG1/zioQH7j/4iMJ07MMPeQNkmj 4kGQOdTcsFfDhYLDdCE5dj5WeE6fYRxEQ3up0ArDSP1L In-Reply-To: <0b9b9c3d-8ba0-4329-9504-b9d33c627649@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e On 7/28/26 09:37, Christian Loehle wrote: > Commit f4c31b07b136 ("sched: idle: Consolidate the handling of two > special cases") changed the no-cpuidle-driver path to use the previous > tick wakeup heuristic. > > Oracle reported a substantial sysbench regression on small OCI VM shapes > with no cpuidle driver available. Reverting the commit recovered the lost > performance. > > Restore the previous tick handling for the no-driver case while retaining > the heuristic for the single-state cpuidle case. > > Fixes: f4c31b07b136 ("sched: idle: Consolidate the handling of two special cases") > Reported-by: Joseph Salisbury > Closes: https://lore.kernel.org/all/096b42fa-107f-450d-b3b1-03bcad3f1e04@oracle.com/ > Signed-off-by: Christian Loehle FWIW: Tested-by: Florian Fainelli We also hit this issue after it got back ported into stable trees (5.15, 6.1, etc.) and this is seen during a network throughput test. This is on an ARM 32-bit platform with: # CONFIG_ARM_CPUIDLE is not set # CONFIG_ARM_PSCI_CPUIDLE is not set Not that we could not fix that, but this platform really only has WFI has the idle state and it looks like other people are impacted anyway. -- Florian