[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 08 Aug 2014 17:27:15 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Mel Gorman <mgorman@...e.de>,
Andrew Morton <akpm@...ux-foundation.org>
CC: Linux Kernel <linux-kernel@...r.kernel.org>,
Linux-MM <linux-mm@...ck.org>,
Linux-FSDevel <linux-fsdevel@...r.kernel.org>,
Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH 6/6] mm: page_alloc: Reduce cost of the fair zone allocation
policy
On 07/09/2014 10:13 AM, Mel Gorman wrote:
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1604,6 +1604,9 @@ again:
> }
>
> __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
This can underflow zero, right?
> + if (zone_page_state(zone, NR_ALLOC_BATCH) == 0 &&
AFAICS, zone_page_state will correct negative values to zero only for
CONFIG_SMP. Won't this check be broken on !CONFIG_SMP?
I just stumbled upon this when trying to optimize the function. I didn't check
how rest of the design copes with negative NR_ALLOC_BATCH values.
> + !zone_is_fair_depleted(zone))
> + zone_set_flag(zone, ZONE_FAIR_DEPLETED);
>
> __count_zone_vm_events(PGALLOC, zone, 1 << order);
> zone_statistics(preferred_zone, zone, gfp_flags);
> @@ -1915,6 +1918,18 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone)
>
> #endif /* CONFIG_NUMA */
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists