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From: Mel Gorman <mgorman@techsingularity.net>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] mm: Disable NUMA_BALANCING_DEFAULT_ENABLED and TRANSPARENT_HUGEPAGE on PREEMPT_RT
Date: Thu, 28 Oct 2021 15:37:48 +0100	[thread overview]
Message-ID: <20211028143748.GU3959@techsingularity.net> (raw)
In-Reply-To: <20211028143327.hfbxjze7palrpfgp@linutronix.de>

On Thu, Oct 28, 2021 at 04:33:27PM +0200, Sebastian Andrzej Siewior wrote:
> TRANSPARENT_HUGEPAGE:
> There are potential non-deterministic delays to an RT thread if a critical
> memory region is not THP-aligned and a non-RT buffer is located in the same
> hugepage-aligned region. It's also possible for an unrelated thread to migrate
> pages belonging to an RT task incurring unexpected page faults due to memory
> defragmentation even if khugepaged is disabled.
> 
> Regular HUGEPAGEs are not affected by this can be used.
> 
> NUMA_BALANCING:
> There is a non-deterministic delay to mark PTEs PROT_NONE to gather NUMA fault
> samples, increased page faults of regions even if mlocked and non-deterministic
> delays when migrating pages.
> 
> [Mel Gorman worded 99% of the commit description].
> 
> Link: https://lore.kernel.org/all/20200304091159.GN3818@techsingularity.net/
> Link: https://lore.kernel.org/all/20211026165100.ahz5bkx44lrrw5pt@linutronix.de/
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Acked-by: Mel Gorman <mgorman@techsingularity.net>

-- 
Mel Gorman
SUSE Labs


  reply	other threads:[~2021-10-28 14:37 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-28 14:33 [PATCH] mm: Disable NUMA_BALANCING_DEFAULT_ENABLED and TRANSPARENT_HUGEPAGE on PREEMPT_RT Sebastian Andrzej Siewior
2021-10-28 14:37 ` Mel Gorman [this message]
2021-10-28 15:54 ` David Hildenbrand
2021-10-28 16:17   ` Sebastian Andrzej Siewior

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