From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 10 Oct 2007 08:04:29 -0700 (PDT) From: Linus Torvalds Subject: Re: remove zero_page (was Re: -mm merge plans for 2.6.24) In-Reply-To: <200710100030.28806.nickpiggin@yahoo.com.au> Message-ID: References: <20071001142222.fcaa8d57.akpm@linux-foundation.org> <200710100030.28806.nickpiggin@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Hugh Dickins , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Wed, 10 Oct 2007, Nick Piggin wrote: > > It just seems like now might be a good time to just _try_ removing > the zero page Yes. Let's do your patch immediately after the x86 merge, and just see if anybody screams. It might take a while, because I certainly agree that whoever would be affected by it is likely to be unusual. > OK, maybe this is where we are not on the same page. > There are 2 issues really. Firstly, performance problem of > refcounting the zero-page -- we've established that it causes > this livelock and that we should stop refcounting it, right? Yes, I do agree that refcounting is problematic. > Second issue is the performance difference between removing the > zero page completely, and de-refcounting it (it's obviously > incorrect to argue for zero page removal for performance reasons > if the performance improvement is simply coming from avoiding > the refcounting). Well, even if it's a "when you don't get into the bad behaviour, performance difference is not measurable", and give a before-and-after number for some random but interesting load. Even if it's just a kernel compile.. Linus -- 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