Re: [PATCH] emulate accessed bit for EPT

2010-02-08 Thread Avi Kivity
On 02/03/2010 11:11 PM, Rik van Riel wrote: Currently KVM pretends that pages with EPT mappings never got accessed. This has some side effects in the VM, like swapping out actively used guest pages and needlessly breaking up actively used hugepages. We can avoid those very costly side effects b

Re: [PATCH] emulate accessed bit for EPT

2010-02-07 Thread Marcelo Tosatti
On Fri, Feb 05, 2010 at 07:14:13PM +0100, Andrea Arcangeli wrote: > On Fri, Feb 05, 2010 at 03:34:23PM -0200, Marcelo Tosatti wrote: > > But perhaps a module parameter to turn accessed bit emulation off might > > be handy in the future? > > Maybe, but somebody should show that this can overall bec

Re: [PATCH] emulate accessed bit for EPT

2010-02-05 Thread Andrea Arcangeli
On Fri, Feb 05, 2010 at 03:34:23PM -0200, Marcelo Tosatti wrote: > But perhaps a module parameter to turn accessed bit emulation off might > be handy in the future? Maybe, but somebody should show that this can overall become a downside, which I doubt... I think if it does, the VM is to blame for

Re: [PATCH] emulate accessed bit for EPT

2010-02-05 Thread Marcelo Tosatti
On Thu, Feb 04, 2010 at 06:47:15PM +0100, Andrea Arcangeli wrote: > On Thu, Feb 04, 2010 at 08:40:43AM -0500, Rik van Riel wrote: > > I suspect it won't be very many. I have been monitoring > > /proc/meminfo on my system while testing this patch, and > > it is quite typical that the size of the ina

Re: [PATCH] emulate accessed bit for EPT

2010-02-04 Thread Andrea Arcangeli
On Thu, Feb 04, 2010 at 08:40:43AM -0500, Rik van Riel wrote: > I suspect it won't be very many. I have been monitoring > /proc/meminfo on my system while testing this patch, and > it is quite typical that the size of the inactive anon > list does not change for minutes at a time. > > In other wor

Re: [PATCH] emulate accessed bit for EPT

2010-02-04 Thread Jeff Dike
On Wed, Feb 03, 2010 at 04:11:03PM -0500, Rik van Riel wrote: > Jeff, does this patch fix the issue you saw a few months ago, with > a 256MB KVM guest in a cgroup limited to 128GB memory? Hum, let me dust off that workload and give it a shot... Jeff -- To unsubscri

Re: [PATCH] emulate accessed bit for EPT

2010-02-04 Thread Balbir Singh
* Rik van Riel [2010-02-04 10:41:14]: > Balbir Singh wrote: > >* Rik van Riel [2010-02-04 08:40:43]: > > > >>On 02/03/2010 11:12 PM, Balbir Singh wrote: > >>>* Rik van Riel [2010-02-03 16:11:03]: > >>> > Currently KVM pretends that pages with EPT mappings never got > accessed. This has

Re: [PATCH] emulate accessed bit for EPT

2010-02-04 Thread Rik van Riel
Balbir Singh wrote: * Rik van Riel [2010-02-04 08:40:43]: On 02/03/2010 11:12 PM, Balbir Singh wrote: * Rik van Riel [2010-02-03 16:11:03]: Currently KVM pretends that pages with EPT mappings never got accessed. This has some side effects in the VM, like swapping out actively used guest p

Re: [PATCH] emulate accessed bit for EPT

2010-02-04 Thread Balbir Singh
* Rik van Riel [2010-02-04 08:40:43]: > On 02/03/2010 11:12 PM, Balbir Singh wrote: > >* Rik van Riel [2010-02-03 16:11:03]: > > > >>Currently KVM pretends that pages with EPT mappings never got > >>accessed. This has some side effects in the VM, like swapping > >>out actively used guest pages

Re: [PATCH] emulate accessed bit for EPT

2010-02-04 Thread Rik van Riel
On 02/03/2010 11:12 PM, Balbir Singh wrote: * Rik van Riel [2010-02-03 16:11:03]: Currently KVM pretends that pages with EPT mappings never got accessed. This has some side effects in the VM, like swapping out actively used guest pages and needlessly breaking up actively used hugepages. We c

Re: [PATCH] emulate accessed bit for EPT

2010-02-03 Thread Balbir Singh
* Rik van Riel [2010-02-03 16:11:03]: > Currently KVM pretends that pages with EPT mappings never got > accessed. This has some side effects in the VM, like swapping > out actively used guest pages and needlessly breaking up actively > used hugepages. > > We can avoid those very costly side eff