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Date: Tue, 11 Jun 2024 10:41:16 +0200
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Celeste Liu <coelacanthushex@gmail.com>
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Subject: Re: [PATCH 3/6] mips: defconfig: drop RT_GROUP_SCHED=y from
 generic/db1xxx/eyeq5
Message-ID: <ZmgNrOr1nalSTeja@alpha.franken.de>
References: <20240530111947.549474-8-CoelacanthusHex@gmail.com>
 <20240530111947.549474-11-CoelacanthusHex@gmail.com>
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In-Reply-To: <20240530111947.549474-11-CoelacanthusHex@gmail.com>

On Thu, May 30, 2024 at 07:19:51PM +0800, Celeste Liu wrote:
> For cgroup v1, if turned on, and there's any cgroup in the "cpu" hierarchy it
> needs an RT budget assigned, otherwise the processes in it will not be able to
> get RT at all. The problem with RT group scheduling is that it requires the
> budget assigned but there's no way we could assign a default budget, since the
> values to assign are both upper and lower time limits, are absolute, and need to
> be sum up to < 1 for each individal cgroup. That means we cannot really come up
> with values that would work by default in the general case.[1]
> 
> For cgroup v2, it's almost unusable as well. If it turned on, the cpu controller
> can only be enabled when all RT processes are in the root cgroup. But it will
> lose the benefits of cgroup v2 if all RT process were placed in the same cgroup.
> 
> Red Hat, Gentoo, Arch Linux and Debian all disable it. systemd also doesn't
> support it.[2]
> 
> [1]: https://bugzilla.redhat.com/show_bug.cgi?id=1229700
> [2]: https://github.com/systemd/systemd/issues/13781#issuecomment-549164383
> 
> Signed-off-by: Celeste Liu <CoelacanthusHex@gmail.com>
> ---
>  arch/mips/configs/db1xxx_defconfig  | 1 -
>  arch/mips/configs/eyeq5_defconfig   | 1 -
>  arch/mips/configs/generic_defconfig | 1 -
>  3 files changed, 3 deletions(-)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]