I was asked to troubleshoot a Xine DVD playback problem on a Dell Inspiron 9100 (P4 3.2 GHz, HT-enabled). DVD playback was "herky-jerky". I found that killing irqbalance or booting without ACPI=on seems to correct the playback. Watching /proc/interrupts (with ACPI=on and irqbalance running) indicates that each time the playback paused CPU1 handled the interrupts for the DVD's IDE controller. When playback was smooth CPU0 was fielding the IDE interrupts. Furthermore, xine was running on CPU0. Without the ACPI=on cmdline parameter all of the interrupts were handled by CPU0. The laptop is running the latest FC1 kernel. Questions: Is there a way to associate a specific program (e.g. xine) with a specific processor and also associate a device's interrupt with a specific processor, without killing irqbalance or disabling ACPI? Does disabling irqbalance cause any significant problems? Performance, or otherwise. Is this likely a problem with a 2.6.x kernel? I do not have an HT-capable FC2 machine handy. Bob...
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