Re: [RFC v2 PATCH 0/4] speed up page allocation for __GFP_ZERO

From: Liang Li
Date: Mon Jan 04 2021 - 09:08:16 EST

On Mon, Jan 4, 2021 at 8:56 PM Michal Hocko <mhocko@xxxxxxxx> wrote:
> On Mon 21-12-20 11:25:22, Liang Li wrote:
> [...]
> > Security
> > ========
> > This is a weak version of "introduce init_on_alloc=1 and init_on_free=1
> > boot options", which zero out page in a asynchronous way. For users can't
> > tolerate the impaction of 'init_on_alloc=1' or 'init_on_free=1' brings,
> > this feauture provide another choice.
> Most of the usecases are about the start up time imporvemtns IIUC. Have
> you tried to use init_on_free or this would be prohibitive for your
> workloads?
I have not tried yet. 'init_on_free' may help to shorten the start up time. In
our use case, we care about both the VM creation time and the VM reboot
time[terminate QEMU process first and launch a new one], 'init_on_free'
will slow down the termination process and is not helpful for VM reboot.
Our aim is to speed up 'VM start up' and not slow down 'VM shut down'.