Date:   Wed, 10 Nov 2021 17:14:02 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Georgi Djakov <quic_c_gdjako@quicinc.com>
Cc:     hannes@cmpxchg.org, vincent.guittot@linaro.org,
        juri.lelli@redhat.com, mingo@redhat.com, rostedt@goodmis.org,
        bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
        mhocko@kernel.org, vdavydov.dev@gmail.com, tj@kernel.org,
        axboe@kernel.dk, cgroups@vger.kernel.org,
        linux-block@vger.kernel.org, akpm@linux-foundation.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org, djakov@kernel.org
Subject: Re: [RFC] psi: Add additional PSI counters for each type of memory
 pressure
Message-ID: <20211110161402.GB174703@worktop.programming.kicks-ass.net>
References: <1636558597-248294-1-git-send-email-quic_c_gdjako@quicinc.com>
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On Wed, Nov 10, 2021 at 07:36:37AM -0800, Georgi Djakov wrote:
> @@ -21,7 +19,18 @@ enum psi_task_count {
>  	 * don't have to special case any state tracking for it.
>  	 */
>  	NR_ONCPU,
> -	NR_PSI_TASK_COUNTS = 4,
> +	NR_BLK_CGROUP_THROTTLE,
> +	NR_BIO,
> +	NR_COMPACTION,
> +	NR_THRASHING,
> +	NR_CGROUP_RECLAIM_HIGH,
> +	NR_CGROUP_RECLAIM_HIGH_SLEEP,
> +	NR_CGROUP_TRY_CHARGE,
> +	NR_DIRECT_COMPACTION,
> +	NR_DIRECT_RECLAIM,
> +	NR_READ_SWAPPAGE,
> +	NR_KSWAPD,
> +	NR_PSI_TASK_COUNTS = 16,
>  };
>  

> @@ -51,9 +80,20 @@ enum psi_states {
>  	PSI_MEM_FULL,
>  	PSI_CPU_SOME,
>  	PSI_CPU_FULL,
> +	PSI_BLK_CGROUP_THROTTLE,
> +	PSI_BIO,
> +	PSI_COMPACTION,
> +	PSI_THRASHING,
> +	PSI_CGROUP_RECLAIM_HIGH,
> +	PSI_CGROUP_RECLAIM_HIGH_SLEEP,
> +	PSI_CGROUP_TRY_CHARGE,
> +	PSI_DIRECT_COMPACTION,
> +	PSI_DIRECT_RECLAIM,
> +	PSI_READ_SWAPPAGE,
> +	PSI_KSWAPD,
>  	/* Only per-CPU, to weigh the CPU in the global average: */
>  	PSI_NONIDLE,
> -	NR_PSI_STATES = 7,
> +	NR_PSI_STATES = 18,
>  };

Have you considered what this does to psi_group_cpu's size and layout
and the impact thereof on performance?