Gracefully handle hotplug in scx_rusty #218
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Newer kernels also support exiting gracefully with an exit code. Let's update the UserExitInfo struct to also read and export this value. Signed-off-by: David Vernet <void@manifault.com>
The scx_rusty scheduler does not support hotplug, and expects a static host topology throughout its runtime. Though the kernel does have support for detecting hotplug events, we currently don't detect this in the kernel, nor surface it to user space when it happens. Now that we have scx_bpf_exit(), we can gracefully exit the kernel in the event of a hotplug, and communicate to user space that it should restart the scheduler. This patch adds that support to scx_rusty. Note that this assumes that we're running on a recent enough kernel that has scx_bpf_exit(). If it doesn't, then we instead just error out of the kernel scheduler and exit the application. Signed-off-by: David Vernet <void@manifault.com>
Byte-Lab
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htejun
approved these changes
Apr 4, 2024
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It'd be nice if there was a generic way to apply this change automatically to all the schedulers, considering that most (all?) of them are not handling CPU hotplugging nicely at the moment, maybe a flag Anyway, this looks good to me for now, I'll do the same in scx_rustland_core. |
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Oh yeah, that's a good idea, definitely seems like this would be something generally useful. @htejun wdyt? |
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Yeah, it'd be nice to make this generic in scx_utils. Traits are tough to do with skels unfortunately, so we might have to do even more macros, which is a bit sad but not the end of the world. |
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The scx_rusty scheduler does not support hotplug, and expects a static
host topology throughout its runtime. Though the kernel does have
support for detecting hotplug events, we currently don't detect this in
the kernel, nor surface it to user space when it happens. Now that we
have scx_bpf_exit(), we can gracefully exit the kernel in the event of a
hotplug, and communicate to user space that it should restart the
scheduler.
This patch adds that support to scx_rusty. Note that this assumes that
we're running on a recent enough kernel that has scx_bpf_exit(). If it
doesn't, then we instead just error out of the kernel scheduler and exit
the application.