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Date: Tue, 15 Aug 2017 10:49:41 +0100
From: Mel Gorman <mgorman@...hsingularity.net>
To: Kemi Wang <kemi.wang@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Michal Hocko <mhocko@...e.com>,
Johannes Weiner <hannes@...xchg.org>,
Dave <dave.hansen@...ux.intel.com>,
Andi Kleen <andi.kleen@...el.com>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Ying Huang <ying.huang@...el.com>,
Aaron Lu <aaron.lu@...el.com>, Tim Chen <tim.c.chen@...el.com>,
Linux MM <linux-mm@...ck.org>,
Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mm: Change the call sites of numa statistics items
On Tue, Aug 15, 2017 at 04:45:35PM +0800, Kemi Wang wrote:
> In this patch, NUMA statistics is separated from zone statistics
> framework, all the call sites of NUMA stats are changed to use
> numa-stats-specific functions, it does not have any functionality change
> except that the value of NUMA stats is shown behind zone page stats, and
> the threshold size of NUMA stats is shown behind pcp threshold when users
> *read* the zone info.
>
> E.g. cat /proc/zoneinfo
> ***Base*** ***With this patch***
> nr_free_pages 3976 nr_free_pages 3976
> nr_zone_inactive_anon 0 nr_zone_inactive_anon 0
> nr_zone_active_anon 0 nr_zone_active_anon 0
> nr_zone_inactive_file 0 nr_zone_inactive_file 0
> nr_zone_active_file 0 nr_zone_active_file 0
> nr_zone_unevictable 0 nr_zone_unevictable 0
> nr_zone_write_pending 0 nr_zone_write_pending 0
> nr_mlock 0 nr_mlock 0
> nr_page_table_pages 0 nr_page_table_pages 0
> nr_kernel_stack 0 nr_kernel_stack 0
> nr_bounce 0 nr_bounce 0
> nr_zspages 0 nr_zspages 0
> numa_hit 0 *nr_free_cma 0*
> numa_miss 0 numa_hit 0
> numa_foreign 0 numa_miss 0
> numa_interleave 0 numa_foreign 0
> numa_local 0 numa_interleave 0
> numa_other 0 numa_local 0
> *nr_free_cma 0* numa_other 0
> ... ...
> vm stats threshold: 10 vm stats threshold: 10
> ... *vm numa stats threshold: 10*
> ...
>
> The next patch updates the numa stats counter size and threshold.
>
> Signed-off-by: Kemi Wang <kemi.wang@...el.com>
> ---
> drivers/base/node.c | 22 ++++---
> include/linux/mmzone.h | 25 +++++---
> include/linux/vmstat.h | 29 +++++++++
> mm/page_alloc.c | 10 +--
> mm/vmstat.c | 167 +++++++++++++++++++++++++++++++++++++++++++++++--
> 5 files changed, 227 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index d8dc830..12080c6 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -160,12 +160,12 @@ static ssize_t node_read_numastat(struct device *dev,
> "interleave_hit %lu\n"
> "local_node %lu\n"
> "other_node %lu\n",
> - sum_zone_node_page_state(dev->id, NUMA_HIT),
> - sum_zone_node_page_state(dev->id, NUMA_MISS),
> - sum_zone_node_page_state(dev->id, NUMA_FOREIGN),
> - sum_zone_node_page_state(dev->id, NUMA_INTERLEAVE_HIT),
> - sum_zone_node_page_state(dev->id, NUMA_LOCAL),
> - sum_zone_node_page_state(dev->id, NUMA_OTHER));
> + sum_zone_node_numa_state(dev->id, NUMA_HIT),
> + sum_zone_node_numa_state(dev->id, NUMA_MISS),
> + sum_zone_node_numa_state(dev->id, NUMA_FOREIGN),
> + sum_zone_node_numa_state(dev->id, NUMA_INTERLEAVE_HIT),
> + sum_zone_node_numa_state(dev->id, NUMA_LOCAL),
> + sum_zone_node_numa_state(dev->id, NUMA_OTHER));
> }
The names are very similar and it would be preferred if the names were
visually different like sum_zone_numa_stat() which is hard to confuse with
the zone stat fields.
> static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL);
>
> @@ -181,9 +181,17 @@ static ssize_t node_read_vmstat(struct device *dev,
> n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
> sum_zone_node_page_state(nid, i));
>
> - for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
> +#ifdef CONFIG_NUMA
> + for (i = 0; i < NR_VM_ZONE_NUMA_STAT_ITEMS; i++)
> n += sprintf(buf+n, "%s %lu\n",
> vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
> + sum_zone_node_numa_state(nid, i));
> +#endif
Similar with NR_VM_ZONE_NUMA_STAT_ITEMS, it's too similar to
NR_VM_NODE_STAT_ITEMS.
> +
> + for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
> + n += sprintf(buf+n, "%s %lu\n",
> + vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
> + NR_VM_ZONE_NUMA_STAT_ITEMS],
> node_page_state(pgdat, i));
>
> return n;
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index fc14b8b..0b11ba7 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -114,6 +114,20 @@ struct zone_padding {
> #define ZONE_PADDING(name)
> #endif
>
> +#ifdef CONFIG_NUMA
> +enum zone_numa_stat_item {
> + NUMA_HIT, /* allocated in intended node */
> + NUMA_MISS, /* allocated in non intended node */
> + NUMA_FOREIGN, /* was intended here, hit elsewhere */
> + NUMA_INTERLEAVE_HIT, /* interleaver preferred this zone */
> + NUMA_LOCAL, /* allocation from local node */
> + NUMA_OTHER, /* allocation from other node */
> + NR_VM_ZONE_NUMA_STAT_ITEMS
> +};
> +#else
> +#define NR_VM_ZONE_NUMA_STAT_ITEMS 0
> +#endif
> +
> enum zone_stat_item {
> /* First 128 byte cacheline (assuming 64 bit words) */
> NR_FREE_PAGES,
> @@ -132,14 +146,6 @@ enum zone_stat_item {
> #if IS_ENABLED(CONFIG_ZSMALLOC)
> NR_ZSPAGES, /* allocated in zsmalloc */
> #endif
> -#ifdef CONFIG_NUMA
> - NUMA_HIT, /* allocated in intended node */
> - NUMA_MISS, /* allocated in non intended node */
> - NUMA_FOREIGN, /* was intended here, hit elsewhere */
> - NUMA_INTERLEAVE_HIT, /* interleaver preferred this zone */
> - NUMA_LOCAL, /* allocation from local node */
> - NUMA_OTHER, /* allocation from other node */
> -#endif
> NR_FREE_CMA_PAGES,
> NR_VM_ZONE_STAT_ITEMS };
>
> @@ -276,6 +282,8 @@ struct per_cpu_pageset {
> struct per_cpu_pages pcp;
> #ifdef CONFIG_NUMA
> s8 expire;
> + s8 numa_stat_threshold;
> + s8 vm_numa_stat_diff[NR_VM_ZONE_NUMA_STAT_ITEMS];
> #endif
> #ifdef CONFIG_SMP
> s8 stat_threshold;
Ok. this slightly increases the size of the per_cpu_pageset due to
numa_stat_threshold. The structure occupes 2 cache lines and still occupies
2 cache lines afterwards so that is ok but consider hard-coding the value
of it. The locality stats are never used as part of a decision made by the
kernel and they get summed when reading proc unconditionally. There is little
benefit to tuning that threshold at all and there should be a very small
performance gain if it's removed because it'll be a compile-time constant.
The rest of the patch is mostly mechanical.
--
Mel Gorman
SUSE Labs
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