From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 10 Nov 2000 09:56:43 +0000 From: "Stephen C. Tweedie" Subject: Re: Question about swap_in() in 2.2.16 .... Message-ID: <20001110095643.A15453@redhat.com> References: <3A08F37A.38C156C1@cse.iitkgp.ernet.in> <20001108100533.C11411@redhat.com> <3A0B7829.B9F33ACA@cse.iitkgp.ernet.in> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3A0B7829.B9F33ACA@cse.iitkgp.ernet.in>; from sganguly@cse.iitkgp.ernet.in on Thu, Nov 09, 2000 at 11:23:05PM -0500 Sender: owner-linux-mm@kvack.org Return-Path: To: Shuvabrata Ganguly Cc: "Stephen C. Tweedie" , linux MM List-ID: Hi, On Thu, Nov 09, 2000 at 11:23:05PM -0500, Shuvabrata Ganguly wrote: > "Stephen C. Tweedie" wrote: > > > Now this creates a read-only mapping even if the access was a "write > > > acess" ( if the page is shared ). Doesnt this mean that an additional > > > "write-protect" fault will be taken immediately when the process tries > > > to write again ? > > > > Yes. > > Then why dont we give it a private page in the first place ? Normal copy-on-write is an extremely performance-critical code path. It's really not worth the trouble of adding extra code to it to make the swapin page fault do the same copy-on-write immediately, because swapin simply is not that important for performance. --Stephen -- 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.eu.org/Linux-MM/