From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx206.postini.com [74.125.245.206]) by kanga.kvack.org (Postfix) with SMTP id 845216B0092 for ; Mon, 2 Apr 2012 10:58:55 -0400 (EDT) Received: by iajr24 with SMTP id r24so5684244iaj.14 for ; Mon, 02 Apr 2012 07:58:54 -0700 (PDT) Date: Mon, 2 Apr 2012 07:58:35 -0700 (PDT) From: Hugh Dickins Subject: RE: swap on eMMC and other flash In-Reply-To: <26E7A31274623843B0E8CF86148BFE326FB55F8B@NTXAVZMBX04.azit.micron.com> Message-ID: References: <201203301744.16762.arnd@arndb.de> <201203301850.22784.arnd@arndb.de> <26E7A31274623843B0E8CF86148BFE326FB55F8B@NTXAVZMBX04.azit.micron.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: "Luca Porzio (lporzio)" Cc: Arnd Bergmann , Rik van Riel , "linaro-kernel@lists.linaro.org" , "linux-mm@kvack.org" , Alex Lemberg , "linux-kernel@vger.kernel.org" , Saugata Das , Venkatraman S , Yejin Moon , Hyojin Jeong , "linux-mmc@vger.kernel.org" , "kernel-team@android.com" On Mon, 2 Apr 2012, Luca Porzio (lporzio) wrote: > > Great topics. As per one of Rik original points: > > > 4) skip writeout of zero-filled pages - this can be a big help > > for KVM virtual machines running Windows, since Windows zeroes > > out free pages; simply discarding a zero-filled page is not > > at all simple in the current VM, where we would have to iterate > > over all the ptes to free the swap entry before being able to > > free the swap cache page (I am not sure how that locking would > > even work) > > > > with the extra layer of indirection, the locking for this scheme > > can be trivial - either the faulting process gets the old page, > > or it gets a new one, either way it'll be zero filled > > > > Since it's KVMs realm here, can't KSM simply solve the zero-filled pages problem avoiding unnecessary burden for the Swap subsystem? I would expect that KSM already does largely handle this, yes. But it's also quite possible that I'm missing Rik's point. Hugh -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org