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From: Hillf Danton <hdanton@sina.com>
To: Bharata B Rao <bharata@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	Yu Zhao <yuzhao@google.com>,
	linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	willy@infradead.org,
	Mel Gorman <mgorman@suse.de>
Subject: Re: Hard and soft lockups with FIO and LTP runs on a large system
Date: Wed, 17 Jul 2024 19:15:10 +0800
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In-Reply-To: <9a53c5cd-6215-4ebd-a17c-1706077a9e65@amd.com>
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On Wed, 17 Jul 2024 16:20:04 +0530 Bharata B Rao <bharata@amd.com>
> On 17-Jul-24 3:07 PM, Vlastimil Babka wrote:
> > 
> > It seems weird to me to see anything that would require ZONE_DMA allocation
> > on a modern system. Do you know where it comes from?
> 
> We measured the lruvec spinlock start, end and hold
> time(htime) using sched_clock(), along with a BUG() if the hold time was
> more than 10s. The below case shows that lruvec spin lock was held for ~25s.
>
What is more unusual could be observed perhaps with your hardware config but
with 386MiB RAM assigned to each node, the so called tight memory but not
extremely tight.