From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 14 Aug 2007 15:20:28 -0700 (PDT) From: Christoph Lameter Subject: Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c In-Reply-To: <20070814221616.GG23308@one.firstfloor.org> Message-ID: References: <20070814204454.GC22202@one.firstfloor.org> <20070814212355.GA23308@one.firstfloor.org> <20070814212955.GC23308@one.firstfloor.org> <20070814214430.GD23308@one.firstfloor.org> <20070814215659.GF23308@one.firstfloor.org> <20070814221616.GG23308@one.firstfloor.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Wed, 15 Aug 2007, Andi Kleen wrote: > > > The interrupt handler shouldn't touch zone_flag. If it wants > > > to it would need to be converted to a local_t and incremented/decremented > > > (should be about the same cost at least on architectures with sane > > > local_t implementation) > > > > That would mean we need to fork the code for reclaim? > > Not with the local_t increment. Ok I have a vague idea on how this could but its likely that the changes make things worse rather than better. Additional reference to a new cacheline (per cpu but still), preempt disable. Lots of code at all call sites. Interrupt enable/disable is quite efficient in recent processors. -- 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