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From Ivan Kudryavtsev <kudryavtsev...@bw-sw.com>
Subject Re: KVM Host overprovisioning
Date Tue, 12 Sep 2017 07:05:22 GMT
Yes, sure.

What I want is an ability to increase host memory rather than decrease it.

So the first suggestion is to add a parameter to increase amount of
megabytes or gigabytes, not necessary a multiplier. Manual adding via
agent.properties is a good way to implement it because different hosts can
have different capabilities (depending on CPU model) and manual "per-host"
configuration is better than just cluster configuration option.

2017-09-12 13:46 GMT+07:00 Wido den Hollander <wido@widodh.nl>:

>
> > Op 11 september 2017 om 13:04 schreef Ivan Kudryavtsev <
> kudryavtsev_ia@bw-sw.com>:
> >
> >
> > Hi, Wido.
> >
> > Yes, you can. But it works not the way I expect because It cuts RAM from
> VM
> > by dividing it to overprovisioning factor like VM with 2GB of RAM with
> > Overprovisioning factor 2.0 will get 1GB displayed with "free" command.
> > That's why I finished the message with words that it might be I just
> don't
> > get the idea. The behaviour is the same in my prod 4.3 and new 4.9.
> >
>
> Hmm, ok.
>
> So for the KVM Agent you can add "host reserved mb" to the
> agent.properties, but you are proposing a setting where you can multiply
> the memory?
>
> Eg by 1.5 if you want to and have the Agent expose that to the MGMT server?
>
> Wido
>
> > 2017-09-11 18:00 GMT+07:00 Wido den Hollander <wido@widodh.nl>:
> >
> > > Hi,
> > >
> > > > Op 10 september 2017 om 8:37 schreef Ivan Kudryavtsev <
> > > kudryavtsev_ia@bw-sw.com>:
> > > >
> > > >
> > > > Hello, community.
> > > >
> > > > During the last years Linux kernel got some interesting features like
> > > KSM,
> > > > ZSWAP, ZRAM. Hardware also steps forward and we see Intel 3d xpoint,
> > > > extremely fast SSD drives with m.2 and PCI-E interfaces.
> > > >
> > > > These facilities enable potentially interesting use of overcommited
> RAM
> > > for
> > > > hosts. According to IBM's investigations Zswap with LZ4/ZBUD
> increases
> > > > virtual RAM on 40%.
> > > >
> > > > I investigated current Apache CloudStack memory overcommitment
> > > capabilities
> > > > and they mostly affect VM's RAM by utilizing ballooning and I think
> it's
> > > > not what necessary to open new facilities. There are many cases
> which can
> > > > utilize ZSWAP and fast swap devices to efficiently provision more RAM
> > > than
> > > > presents.
> > > >
> > > > I suppose, CloudStack Agent for KVM can have configured parameter
> which
> > > > "mangles" RAM reported. From the other hand it can be done by
> implemented
> > > > host properties on server side. I tried manual increasing in host
> table:
> > > >
> > > > update host set ram=ram * 1.4 where id=1;
> > > >
> > > > and it seems until the next host stats update it works as expected. I
> > > think
> > > > this workaround is useful, but it's better to have the function in
> core
> > > > like standard.
> > > >
> > >
> > > Can't you set memory over provisioning on a cluster basis in the GUI? I
> > > thought you could.
> > >
> > > Wido
> > >
> > > > Let me know what you think about it, it might be I don't understand
> > > > something and ACS already has it in place? I also would like to hear
> your
> > > > thoughts on ZSWAP usage in practice.
> > > >
> > > > --
> > > > With best regards, Ivan Kudryavtsev
> > > > Bitworks Software, Ltd.
> > > > Cell: +7-923-414-1515
> > > > WWW: http://bitworks.software/ <http://bw-sw.com/>
> > >
> >
> >
> >
> > --
> > With best regards, Ivan Kudryavtsev
> > Bitworks Software, Ltd.
> > Cell: +7-923-414-1515
> > WWW: http://bitworks.software/ <http://bw-sw.com/>
>



-- 
With best regards, Ivan Kudryavtsev
Bitworks Software, Ltd.
Cell: +7-923-414-1515
WWW: http://bitworks.software/ <http://bw-sw.com/>

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