linux-kernel - Re: [PATCH 9/9] sched/psi: add PSI_IRQ to track IRQ/SOFTIRQ pressure

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Message-ID: <YuFitL6KuCfuqujn@worktop.programming.kicks-ass.net>
Date:   Wed, 27 Jul 2022 18:07:16 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Chengming Zhou <zhouchengming@...edance.com>
Cc:     hannes@...xchg.org, surenb@...gle.com, mingo@...hat.com,
        tj@...nel.org, corbet@....net, akpm@...ux-foundation.org,
        rdunlap@...radead.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, songmuchun@...edance.com,
        cgroups@...r.kernel.org
Subject: Re: [PATCH 9/9] sched/psi: add PSI_IRQ to track IRQ/SOFTIRQ pressure

On Thu, Jul 21, 2022 at 12:04:39PM +0800, Chengming Zhou wrote:
> diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h
> index c124f7d186d0..195f123b1cd1 100644
> --- a/include/linux/psi_types.h
> +++ b/include/linux/psi_types.h
> @@ -47,7 +47,8 @@ enum psi_res {
>  	PSI_IO,
>  	PSI_MEM,
>  	PSI_CPU,
> -	NR_PSI_RESOURCES = 3,
> +	PSI_IRQ,
> +	NR_PSI_RESOURCES = 4,
>  };
>  
>  /*
> @@ -63,9 +64,11 @@ enum psi_states {
>  	PSI_MEM_FULL,
>  	PSI_CPU_SOME,
>  	PSI_CPU_FULL,
> +	PSI_IRQ_SOME,
> +	PSI_IRQ_FULL,
>  	/* Only per-CPU, to weigh the CPU in the global average: */
>  	PSI_NONIDLE,
> -	NR_PSI_STATES = 7,
> +	NR_PSI_STATES = 9,
>  };
>  
>  enum psi_aggregators {

$ pahole -EC psi_group_cpu defconfig-build/kernel/sched/build_utility.o
struct psi_group_cpu {
        /* typedef seqcount_t */ struct seqcount {
                unsigned int       sequence;                                             /*     0     4 */
        } seq __attribute__((__aligned__(64))); /*     0     4 */
        unsigned int               tasks[5];                                             /*     4    20 */
        /* typedef u32 -> __u32 */ unsigned int               state_mask;                /*    24     4 */
        /* typedef u32 -> __u32 */ unsigned int               times[7];                  /*    28    28 */
        /* typedef u64 -> __u64 */ long long unsigned int     state_start;               /*    56     8 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        /* typedef u32 -> __u32 */ unsigned int               times_prev[2][7] __attribute__((__aligned__(64))); /*    64    56 */

        /* size: 128, cachelines: 2, members: 6 */
        /* padding: 8 */
        /* forced alignments: 2 */
} __attribute__((__aligned__(64)));


$ pahole -EC psi_group_cpu defconfig-build/kernel/sched/build_utility.o
struct psi_group_cpu {
        /* typedef seqcount_t */ struct seqcount {
                unsigned int       sequence;                                             /*     0     4 */
        } seq __attribute__((__aligned__(64))); /*     0     4 */
        unsigned int               tasks[5];                                             /*     4    20 */
        /* typedef u32 -> __u32 */ unsigned int               state_mask;                /*    24     4 */
        /* typedef u32 -> __u32 */ unsigned int               times[9];                  /*    28    36 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        /* typedef u64 -> __u64 */ long long unsigned int     state_start;               /*    64     8 */

        /* XXX 56 bytes hole, try to pack */

        /* --- cacheline 2 boundary (128 bytes) --- */
        /* typedef u32 -> __u32 */ unsigned int               times_prev[2][9] __attribute__((__aligned__(64))); /*   128    72 */

        /* size: 256, cachelines: 4, members: 6 */
        /* sum members: 144, holes: 1, sum holes: 56 */
        /* padding: 56 */
        /* forced alignments: 2, forced holes: 1, sum forced holes: 56 */
} __attribute__((__aligned__(64)));


So yeah, I think not.