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From:   Roman Gushchin <guro@fb.com>
To:     Johannes Weiner <hannes@cmpxchg.org>
CC:     Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH 1/8] mm: vmscan: simplify lruvec_lru_size()
Thread-Topic: [PATCH 1/8] mm: vmscan: simplify lruvec_lru_size()
Thread-Index: AQHViOfEo5akA3poAU6bhyPJDLwASqdnCQ0A
Date:   Tue, 22 Oct 2019 19:18:10 +0000
Message-ID: <20191022191806.GA11461@tower.DHCP.thefacebook.com>
References: <20191022144803.302233-1-hannes@cmpxchg.org>
 <20191022144803.302233-2-hannes@cmpxchg.org>
In-Reply-To: <20191022144803.302233-2-hannes@cmpxchg.org>
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On Tue, Oct 22, 2019 at 10:47:56AM -0400, Johannes Weiner wrote:
> This function currently takes the node or lruvec size and subtracts
> the zones that are excluded by the classzone index of the
> allocation. It uses four different types of counters to do this.
>=20
> Just add up the eligible zones.
>=20
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> ---
>  mm/vmscan.c | 21 +++++----------------
>  1 file changed, 5 insertions(+), 16 deletions(-)
>=20
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 1154b3a2b637..57f533b808f2 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -351,32 +351,21 @@ unsigned long zone_reclaimable_pages(struct zone *z=
one)
>   */
>  unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, =
int zone_idx)
>  {
> -	unsigned long lru_size =3D 0;
> +	unsigned long size =3D 0;
>  	int zid;
> =20
> -	if (!mem_cgroup_disabled()) {
> -		for (zid =3D 0; zid < MAX_NR_ZONES; zid++)
> -			lru_size +=3D mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
> -	} else
> -		lru_size =3D node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
> -
> -	for (zid =3D zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
> +	for (zid =3D 0; zid <=3D zone_idx; zid++) {
>  		struct zone *zone =3D &lruvec_pgdat(lruvec)->node_zones[zid];
> -		unsigned long size;
> =20
>  		if (!managed_zone(zone))
>  			continue;
> =20
>  		if (!mem_cgroup_disabled())
> -			size =3D mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
> +			size +=3D mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
>  		else
> -			size =3D zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid],
> -				       NR_ZONE_LRU_BASE + lru);
> -		lru_size -=3D min(size, lru_size);
> +			size +=3D zone_page_state(zone, NR_ZONE_LRU_BASE + lru);
>  	}
> -
> -	return lru_size;
> -
> +	return size;

Neat!

Reviewed-by: Roman Gushchin <guro@fb.com>

Thanks!