Re: [PATCH 0/2] psi: enhance psi with the help of ebpf

[Johannes Weiner]

On Thu, Mar 26, 2020 at 07:12:05AM -0400, Yafang Shao wrote:
> PSI gives us a powerful way to anaylze memory pressure issue, but we can
> make it more powerful with the help of tracepoint, kprobe, ebpf and etc.
> Especially with ebpf we can flexiblely get more details of the memory
> pressure.
> 
> In orderc to achieve this goal, a new parameter is added into
> psi_memstall_{enter, leave}, which indicates the specific type of a
> memstall. There're totally ten memstalls by now,
>         MEMSTALL_KSWAPD
>         MEMSTALL_RECLAIM_DIRECT
>         MEMSTALL_RECLAIM_MEMCG
>         MEMSTALL_RECLAIM_HIGH
>         MEMSTALL_KCOMPACTD
>         MEMSTALL_COMPACT
>         MEMSTALL_WORKINGSET_REFAULT
>         MEMSTALL_WORKINGSET_THRASHING
>         MEMSTALL_MEMDELAY
>         MEMSTALL_SWAPIO

What does this provide over the events tracked in /proc/vmstats?

Can you elaborate a bit how you are using this information? It's not
quite clear to me from the example in patch #2.