* Dave Chinner <david@xxxxxxxxxxxxx> [2011-04-01 08:40:33]: > On Wed, Mar 30, 2011 at 11:00:26AM +0530, Balbir Singh wrote: > > > > The following series implements page cache control, > > this is a split out version of patch 1 of version 3 of the > > page cache optimization patches posted earlier at > > Previous posting http://lwn.net/Articles/425851/ and analysis > > at http://lwn.net/Articles/419713/ > > > > Detailed Description > > ==================== > > This patch implements unmapped page cache control via preferred > > page cache reclaim. The current patch hooks into kswapd and reclaims > > page cache if the user has requested for unmapped page control. > > This is useful in the following scenario > > - In a virtualized environment with cache=writethrough, we see > > double caching - (one in the host and one in the guest). As > > we try to scale guests, cache usage across the system grows. > > The goal of this patch is to reclaim page cache when Linux is running > > as a guest and get the host to hold the page cache and manage it. > > There might be temporary duplication, but in the long run, memory > > in the guests would be used for mapped pages. > > What does this do that "cache=none" for the VMs and using the page > cache inside the guest doesn't acheive? That avoids double caching > and doesn't require any new complexity inside the host OS to > acheive... > There was a long discussion on cache=none in the first posting and the downsides/impact on throughput. Please see http://www.mail-archive.com/kvm@xxxxxxxxxxxxxxx/msg30655.html -- Three Cheers, Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>