linux-kernel - Re: [RFC v2 PATCH 0/4] speed up page allocation for __GFP

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Message-ID: <CA+2MQi9iViYq7+apaJEymt8rZxUuo+9EJN4x3_RRydjr7-vwMQ@mail.gmail.com>
Date:   Mon, 4 Jan 2021 22:07:05 +0800
From:   Liang Li <liliang324@...il.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Liang Li <liliang.opensource@...il.com>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Liang Li <liliangleo@...iglobal.com>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org
Subject: Re: [RFC v2 PATCH 0/4] speed up page allocation for __GFP_ZERO

On Mon, Jan 4, 2021 at 8:56 PM Michal Hocko <mhocko@...e.com> 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'.

Thanks
Liang