Re: [PATCH mm v5 0/4] memcg: Slow down swap allocation as the available space gets depleted

[Jakub Kicinski <kuba@kernel.org>]

On Wed, 20 May 2020 17:20:06 -0700 Jakub Kicinski wrote:
> Tejun describes the problem as follows:
> 
> When swap runs out, there's an abrupt change in system behavior -
> the anonymous memory suddenly becomes unmanageable which readily
> breaks any sort of memory isolation and can bring down the whole
> system. To avoid that, oomd [1] monitors free swap space and triggers
> kills when it drops below the specific threshold (e.g. 15%).
> 
> While this works, it's far from ideal:
>  - Depending on IO performance and total swap size, a given
>    headroom might not be enough or too much.
>  - oomd has to monitor swap depletion in addition to the usual
>    pressure metrics and it currently doesn't consider memory.swap.max.
> 
> Solve this by adapting parts of the approach that memory.high uses -
> slow down allocation as the resource gets depleted turning the
> depletion behavior from abrupt cliff one to gradual degradation
> observable through memory pressure metric.
> 
> [1] https://github.com/facebookincubator/oomd
> 
> v4: https://lore.kernel.org/linux-mm/20200519171938.3569605-1-kuba@kernel.org/
> v3: https://lore.kernel.org/linux-mm/20200515202027.3217470-1-kuba@kernel.org/
> v2: https://lore.kernel.org/linux-mm/20200511225516.2431921-1-kuba@kernel.org/
> v1: https://lore.kernel.org/linux-mm/20200417010617.927266-1-kuba@kernel.org/

Ah, damn, I forgot to add Shakeel's review tags, let me resend.