From: Mel Gorman <mgorman@techsingularity.net>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>,
linux-mm@kvack.org, kernel@pengutronix.de,
patchwork-lst@pengutronix.de
Subject: Re: [PATCH] mm: page_alloc: avoid excessive IRQ disabled times in free_unref_page_list
Date: Thu, 7 Dec 2017 19:51:03 +0000 [thread overview]
Message-ID: <20171207195103.dkiqjoeasr35atqj@techsingularity.net> (raw)
In-Reply-To: <20171207170314.4419-1-l.stach@pengutronix.de>
On Thu, Dec 07, 2017 at 06:03:14PM +0100, Lucas Stach wrote:
> Since 9cca35d42eb6 (mm, page_alloc: enable/disable IRQs once when freeing
> a list of pages) we see excessive IRQ disabled times of up to 250ms on an
> embedded ARM system (tracing overhead included).
>
> This is due to graphics buffers being freed back to the system via
> release_pages(). Graphics buffers can be huge, so it's not hard to hit
> cases where the list of pages to free has 2048 entries. Disabling IRQs
> while freeing all those pages is clearly not a good idea.
>
250ms to free 2048 entries? That seems excessive but I guess the
embedded ARM system is not that fast.
> Introduce a batch limit, which allows IRQ servicing once every few pages.
> The batch count is the same as used in other parts of the MM subsystem
> when dealing with IRQ disabled regions.
>
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Thanks.
Acked-by: Mel Gorman <mgorman@techsingularity.net>
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2017-12-07 19:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-07 17:03 [PATCH] mm: page_alloc: avoid excessive IRQ disabled times in free_unref_page_list Lucas Stach
2017-12-07 19:51 ` Mel Gorman [this message]
2017-12-07 23:20 ` Andrew Morton
2017-12-08 0:25 ` Mel Gorman
2017-12-08 0:53 ` Andrew Morton
2017-12-08 10:21 ` Mel Gorman
2017-12-08 10:03 ` Lucas Stach
2017-12-08 11:38 ` Mel Gorman
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