linux-kernel - Re: [PATCH v3 5/8] mm: don't track number of pages during deferred initialization

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Message-ID: <CAKgT0UcVRMWpaxYu9SQnTuQZm6ePBJkTStWPwekzkfRMnLvf1Q@mail.gmail.com>
Date:   Wed, 27 May 2020 14:18:30 -0700
From:   Alexander Duyck <alexander.duyck@...il.com>
To:     Daniel Jordan <daniel.m.jordan@...cle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        David Hildenbrand <david@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Jonathan Corbet <corbet@....net>,
        Josh Triplett <josh@...htriplett.org>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Michal Hocko <mhocko@...nel.org>, Pavel Machek <pavel@....cz>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Robert Elliott <elliott@....com>,
        Shile Zhang <shile.zhang@...ux.alibaba.com>,
        Steven Sistare <steven.sistare@...cle.com>,
        Tejun Heo <tj@...nel.org>, Zi Yan <ziy@...dia.com>,
        linux-crypto@...r.kernel.org, linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, linux-s390@...r.kernel.org,
        "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" 
        <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v3 5/8] mm: don't track number of pages during deferred initialization

On Wed, May 27, 2020 at 10:37 AM Daniel Jordan
<daniel.m.jordan@...cle.com> wrote:
>
> Deferred page init used to report the number of pages initialized:
>
>   node 0 initialised, 32439114 pages in 97ms
>
> Tracking this makes the code more complicated when using multiple
> threads.  Given that the statistic probably has limited value,
> especially since a zone grows on demand so that the page count can vary,
> just remove it.
>
> The boot message now looks like
>
>   node 0 deferred pages initialised in 97ms
>
> Signed-off-by: Daniel Jordan <daniel.m.jordan@...cle.com>
> Suggested-by: Alexander Duyck <alexander.h.duyck@...ux.intel.com>

This looks good to me.

Reviewed-by: Alexander Duyck <alexander.h.duyck@...ux.intel.com>

> ---
>  mm/page_alloc.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d0c0d9364aa6d..d64f3027fdfa6 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1819,7 +1819,7 @@ static int __init deferred_init_memmap(void *data)
>  {
>         pg_data_t *pgdat = data;
>         const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
> -       unsigned long spfn = 0, epfn = 0, nr_pages = 0;
> +       unsigned long spfn = 0, epfn = 0;
>         unsigned long first_init_pfn, flags;
>         unsigned long start = jiffies;
>         struct zone *zone;
> @@ -1868,15 +1868,15 @@ static int __init deferred_init_memmap(void *data)
>          * allocator.
>          */
>         while (spfn < epfn) {
> -               nr_pages += deferred_init_maxorder(&i, zone, &spfn, &epfn);
> +               deferred_init_maxorder(&i, zone, &spfn, &epfn);
>                 cond_resched();
>         }
>  zone_empty:
>         /* Sanity check that the next zone really is unpopulated */
>         WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
>
> -       pr_info("node %d initialised, %lu pages in %ums\n",
> -               pgdat->node_id, nr_pages, jiffies_to_msecs(jiffies - start));
> +       pr_info("node %d deferred pages initialised in %ums\n",
> +               pgdat->node_id, jiffies_to_msecs(jiffies - start));
>
>         pgdat_init_report_one_done();
>         return 0;
> --
> 2.26.2
>
>