linux-kernel - Re: [PATCH v28 0/4] Virtio-balloon: support free page reporting

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Message-ID: <20180209051212-mutt-send-email-mst@kernel.org>
Date:   Fri, 9 Feb 2018 05:14:42 +0200
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Wei Wang <wei.w.wang@...el.com>
Cc:     virtio-dev@...ts.oasis-open.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, mhocko@...nel.org, akpm@...ux-foundation.org,
        pbonzini@...hat.com, liliang.opensource@...il.com,
        yang.zhang.wz@...il.com, quan.xu0@...il.com, nilal@...hat.com,
        riel@...hat.com, huangzhichao@...wei.com, dgilbert@...hat.com
Subject: Re: [PATCH v28 0/4] Virtio-balloon: support free page reporting

On Fri, Feb 09, 2018 at 11:11:39AM +0800, Wei Wang wrote:
> On 02/09/2018 03:55 AM, Michael S. Tsirkin wrote:
> > On Thu, Feb 08, 2018 at 05:50:16PM +0800, Wei Wang wrote:
> > 
> > > Details:
> > > Set up a Ping-Pong local live migration, where the guest ceaselessy
> > > migrates between the source and destination. Linux compilation,
> > > i.e. make bzImage -j4, is performed during the Ping-Pong migration. The
> > > legacy case takes 5min14s to finish the compilation. With this
> > > optimization patched, it takes 5min12s.
> > How is migration time affected in this case?
> 
> 
> When the linux compilation workload runs, the migration time (both the
> legacy and this optimization case) varies as the compilation goes on. It
> seems not easy to give a static speedup number, some times the migration
> time is reduced to 33%, sometimes to 50%, it varies, and depends on how much
> free memory the system has at that moment. For example, at the later stage
> of the compilation, I can observe 5GB memory being used as page cache. But
> overall, I can observe obvious improvement of the migration time.
> 
> 
> Best,
> Wei

You can run multiple tests and give a best, worst and median numbers.

-- 
MST