> 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... Right. "cache=none" has no double caching issue and KSM already solved cross gues cache sharing. So, I _guess_ this is not a core motivation of his patch. But I'm not him. I'm not sure. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
