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From: Johannes Weiner <jweiner@redhat.com>
To: Bob Liu <lliubbo@gmail.com>
Cc: aarcange@redhat.com, linux-mm@kvack.org,
	akpm@linux-foundation.org, hannes@cmpxchg.org, riel@redhat.com
Subject: Re: [RFC PATCH] mm: thp: make swap configurable
Date: Wed, 12 Oct 2011 05:59:53 -0400	[thread overview]
Message-ID: <20111012095953.GB3160@redhat.com> (raw)
In-Reply-To: <1318255086-7393-1-git-send-email-lliubbo@gmail.com>

On Mon, Oct 10, 2011 at 09:58:06PM +0800, Bob Liu wrote:
> Currently THP do swap by default, user has no control of it.
> But some applications are swap sensitive, this patch add a boot param
> and sys file to make it configurable.

What's special about THP compared to regular-sized anon pages?

> @@ -155,10 +156,11 @@ int add_to_swap(struct page *page)
>  		return 0;
>  
>  	if (unlikely(PageTransHuge(page)))
> -		if (unlikely(split_huge_page(page))) {
> -			swapcache_free(entry, NULL);
> -			return 0;
> -		}
> +		if(!transparent_hugepage_swap_disable())
> +			if (unlikely(split_huge_page(page))) {
> +				swapcache_free(entry, NULL);
> +				return 0;
> +			}
>  
>  	/*
>  	 * Radix-tree node allocations from PF_MEMALLOC contexts could

That will just prevent the splitting and then add the huge page to the
swap cache, for which it is not prepared.

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      parent reply	other threads:[~2011-10-12 10:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-10 13:58 [RFC PATCH] mm: thp: make swap configurable Bob Liu
2011-10-10 14:18 ` Andrea Arcangeli
2011-10-11  9:24   ` Bob Liu
2011-10-11 13:40     ` Rik van Riel
2011-10-11 21:01     ` Andrea Arcangeli
2011-10-12  9:59 ` Johannes Weiner [this message]

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