linux-kernel - Re: [PATCH 29 of 66] don't alloc harder for gfp nomemalloc even if nowait

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Message-Id: <20101109120549.BC48.A69D9226@jp.fujitsu.com>
Date:	Tue,  9 Nov 2010 12:05:40 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com, linux-mm@...ck.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Adam Litke <agl@...ibm.com>, Avi Kivity <avi@...hat.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Ingo Molnar <mingo@...e.hu>, Mike Travis <travis@....com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Chris Wright <chrisw@...s-sol.org>, bpicco@...hat.com,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	Chris Mason <chris.mason@...cle.com>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 29 of 66] don't alloc harder for gfp nomemalloc even if nowait

> From: Andrea Arcangeli <aarcange@...hat.com>
> 
> Not worth throwing away the precious reserved free memory pool for allocations
> that can fail gracefully (either through mempool or because they're transhuge
> allocations later falling back to 4k allocations).
> 
> Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
> Acked-by: Rik van Riel <riel@...hat.com>
> ---
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1941,7 +1941,12 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
>  	alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH);
>  
>  	if (!wait) {
> -		alloc_flags |= ALLOC_HARDER;
> +		/*
> +		 * Not worth trying to allocate harder for
> +		 * __GFP_NOMEMALLOC even if it can't schedule.
> +		 */
> +		if  (!(gfp_mask & __GFP_NOMEMALLOC))
> +			alloc_flags |= ALLOC_HARDER;
>  		/*
>  		 * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
>  		 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.

I like this.
	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>




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