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Allow clean exits from the scheduler with scx_bpf_exit() #166
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Spoke offline with Tejun. Going to change a few things around and send a v2 |
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Oops, missed fixing up scx_ops_exit_kind(). Will resend another patch shortly |
There may be cases where a scheduler wants to cause itself to exit under normal circumstances. For example, if a scheduler does not support hotplug, it may want to exit to user space if a CPU is hotplugged or unplugged to let it know that it should restart itself. To enable this, we implement a new kfunc called scx_bpf_exit_bstr(). This kfunc shares a good amount of logic with scx_bpf_error_bstr(), as both of them can plumb an exit message from BPF to user space. In addition, we also augment struct scx_exit_info to include an exit code field. Signed-off-by: David Vernet <void@manifault.com>
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As with scx_bpf_error(), we want schedulers to have an ergonomic API for exiting execution. Let's add an scx_bpf_exit() macro wrapper that does nearly the same thing as scx_bpf_error(), but invokes scx_bpf_exit_bstr() instead of scx_bpf_error_bstr(). Signed-off-by: David Vernet <void@manifault.com>
We no longer have scx_bpf_switch_all(). Let's update the test to use __COMPAT_SCX_OPS_SWITCH_PARTIAL. Along the way, make it less flaky. Signed-off-by: David Vernet <void@manifault.com>
Let's add a selftest that verifies us using scx_bpf_exit() to exit from various callbacks in the program. Signed-off-by: David Vernet <void@manifault.com>
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@htejun, this should be ready for another look |
htejun
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Mar 28, 2024
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There may be cases where a scheduler wants to cause itself to exit under
normal circumstances. For example, if a scheduler does not support
hotplug, it may want to exit to user space if a CPU is hotplugged or
unplugged to let it know that it should restart itself.
To enable this, we implement a new kfunc called scx_bpf_exit_bstr().
This kfunc shares a good amount of logic with scx_bpf_error_bstr(), as
both of them can plumb an exit message from BPF to user space. In
addition, we also augment struct scx_exit_info to include an exit code
field.