On Fri Apr 28 2023, Sebastian Andrzej Siewior wrote: > On 2023-04-27 15:45:09 [+0200], Kurt Kanzenbach wrote: >> > Are we aware of other concrete case where it bites? Even with just >> > "normal" contented spin_lock usage? >> >> Well, some years ago I've observed a similar problem with ARM64 >> spinlocks, cpu_relax() and retry loops (in the futex code). It also >> generated latency spikes up to 2-3ms. Back then, it was easily >> reproducible using stress-ng --ptrace 4. > > That was fixed by > https://patchwork.kernel.org/project/linux-arm-kernel/patch/1399528508-2806-1-git-send-email-arjun.kv@xxxxxxxxxxx > > if my memory serves me well. We've had a different processor, but yes, we configured CPUACTLR_EL1[31] to 1 in U-Boot to avoid any kernel modifications. Maybe it helps here too? Thanks, Kurt [1] - https://developer.arm.com/documentation/100095/0003/way1382037666700
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