From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 4D65D6B004D for ; Sat, 31 Oct 2009 14:41:05 -0400 (EDT) Date: Sat, 31 Oct 2009 19:40:54 +0100 From: Pavel Machek Subject: Re: [PATCH 2/3] page allocator: Do not allow interrupts to use ALLOC_HARDER Message-ID: <20091031184054.GB1475@ucw.cz> References: <1256650833-15516-1-git-send-email-mel@csn.ul.ie> <1256650833-15516-3-git-send-email-mel@csn.ul.ie> <20091027130924.fa903f5a.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: Andrew Morton , Mel Gorman , stable@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Frans Pop , Jiri Kosina , Sven Geggus , Karol Lewandowski , Tobias Oetiker , KOSAKI Motohiro , Pekka Enberg , Rik van Riel , Christoph Lameter , Stephan von Krawczynski , kernel-testers@vger.kernel.org List-ID: On Tue 2009-10-27 14:12:36, David Rientjes wrote: > On Tue, 27 Oct 2009, Andrew Morton wrote: > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > index dfa4362..7f2aa3e 100644 > > > --- a/mm/page_alloc.c > > > +++ b/mm/page_alloc.c > > > @@ -1769,7 +1769,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask) > > > * See also cpuset_zone_allowed() comment in kernel/cpuset.c. > > > */ > > > alloc_flags &= ~ALLOC_CPUSET; > > > - } else if (unlikely(rt_task(p))) > > > + } else if (unlikely(rt_task(p)) && !in_interrupt()) > > > alloc_flags |= ALLOC_HARDER; > > > > > > if (likely(!(gfp_mask & __GFP_NOMEMALLOC))) { > > > > What are the runtime-observeable effects of this change? > > > > Giving rt tasks access to memory reserves is necessary to reduce latency, > the privilege does not apply to interrupts that subsequently get run on > the same cpu. If rt task needs to allocate memory like that, then its broken, anyway... -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org