Introducción a conceptos de SQL Server Secure Enclaves
Dynamic Memory Management Hyperv 2008 R2 S
1. Hyper-V and Dynamic Memory in Depth
Dr. Eduardo Castro Martínez
Microsoft MVP
ecastro@mswindowscr.org
http://comunidadwindows.org
http://ecastrom.blogspot.com
3. Windows 2008 R2 SP1 Overview
• New capabilities that will enhance both virtualized server
and virtualized desktop deployments
– Remote FX: With Microsoft RemoteFX, users will be
able to work remotely in a Windows Aero desktop
environment, watch full-motion video, enjoy
Silverlight animations, and run 3D applications within
a Hyper-V VM – all with the fidelity of a local-like
performance.
– Hyper-V Dynamic Memory: With Hyper-V Dynamic
Memory, Hyper-V will enable greater virtual machine
density suitable for servers and VDI deployments.
5. No one can size VMs
• How much memory does an IIS server actually need?
• SQL Server
• Print server?
• File server?
• Branch Cache?
• Direct Access?
• How much will performance be affected if you halved the
amount of memory in a VM?
6. No one wants to size VMs
“New virtual machines get 1GB of RAM [no matter what the
VM is running]. I only give people more memory if they
complain about performance”
“All VMs get 4GB of RAM [I have no idea what is happening
with that memory] and no one complains”
“I take the minimum system requirements and add (insert
one: 50%, 100%, 150%)”
“A vendor tells me their app needs 4GB of RAM. I do not
have the time to test this to find out if it is true or not”
7. Virtualization and memory
• Use physical memory as efficiently and dynamically
as possible with minimal performance impact.
– Customers investing in virtualization hosts are
purchasing systems with larger memory
configurations (32 GB, 64 GB, 128 GB and more) and
want to fully utilize this system asset.
– At the same time, they’re purchasing this memory to
provide superior performance and to avoid paging.
• Provide consistent performance and scalability.
– One frequent comment from virtualization users is
that they don’t want a feature with a performance cliff
or inconsistent, variable performance.
8. Virtualization & Memory
• Memory
– Key factor to the number of running VMs
– Possibly most expensive asset in system
• Customer Requirements
– Maximum density, without sacrificing performance
– Maintain consistent performance
– Don’t provide a feature that’s unsuitable for
production use
9. Virtual Machine Performance & Density
• Hyper-V Dynamic Memory is a memory management
enhancement for Hyper-V designed for production use
that enables customers to achieve higher
consolidation/VM density ratios
11. Dynamic Memory Goals
• Higher VM consolidation ratios with minimal
performance impact
– Dependent on:
• How much variation in memory utilization the workloads
have
• How good a job you did of sizing the systems in the first
place
• Work well for both server and desktop workloads
• Add minimal overhead to the system
• Pass the “that looks right” test
12. Adding/Removing Memory
• Adding Memory
– Enlightened fashion
• Synthetic Memory Driver (VSP/VSC Pair)
– No hardware emulation
– Light weight
• Removing Memory
– Wanted to remove memory
– Ballooning is more efficient
• Messes up task manager in the guest OS
13. System Requirements
• Parent Requirements:
– Windows Server 2008 R2 SP1
– Microsoft Hyper-V Server 2008 R2 SP1
• Windows Server 2003, 2008 & 2008 R2
• 32-bit & 64-bit versions
– Windows Vista and Windows 7
• Enterprise and Ultimate Editions only
• 32-bit & 64-bit versions
15. Provided by:
Dynamic Memory Architecture OS
Microsoft Hyper-V
Dynamic Memory Components
Guest Applications
VMWP
Memory
Balancer
DM
VDEV/VSP
User
VMMS Interface
Mode
Memory
GMO
Balancer
Memory
Manager
Windows Windows Kernel
Mode
Kernel Kernel
DM VSC
VID
VMBus VMBus
Hypervisor
16. Example
0 512 MB 1024MB
Hot-add
VM Memory
Ballooned Memory
VM Memory
Parent Memory Second VM Memory Hot-add
17. Startup & Max
• Startup: amount of memory to boot
VM
– BIOS does not know about DM
– Guest OS may not know about DM
– Default: 512MB
• Max: don’t let the VM above this
amount
– Default: 64GB
18. Availability & Priority
• Availability is a concept
– How much memory does the VM have?
– How much memory does the VM want?
– The difference is the availability
• Priority: which VM gets the memory first
– 1-10,000: default is 5,000
– The higher the priority, the higher the availability
19. Memory Buffer
• How much “free” memory should we try and keep in the
VM?
– Allows for responsiveness to bursty workloads
– Can be used for file cache
“I like to configure my virtual machines so that they
have ~20% free memory”
22. Changes to Root Reserve
• Hyper-V has always had the concept of a reserve of
memory that is kept for the parent partition
• DM allows VMs to push up against the reserve
consistently
• New behavior to better protect the parent partition from
rampaging virtual machines
– New registry key in place
• Allows you to reserve static memory for the parent partition
– May result in less memory being available for VMs
23. Changes to NUMA management…
• Wait – what is NUMA?
• Why do I care?
• How does this work today?
26. Why do I care?
• VM memory should come from the “local NUMA node”
27. Why do I care?
• VM memory should come from the “local NUMA node”
28. How does this work today?
• Hyper-V tries to get all memory for a virtual machine
from a single NUMA node
• When it cannot – the virtual machine “spans” NUMA
nodes
• Users can set preferred NUMA nodes for virtual
machines in order to get the best distribution
29. Changes to NUMA management
• Dynamic memory can result in more virtual machines
spanning NUMA nodes
– A virtual machine might start all on one node – but
added memory might come from another node
• New option to disable NUMA node spanning
32. Understanding philosophical differences
• Microsoft
– Understands what guest information to use
• Building on top of guest OS knowledge
– Trying to get the “best bang for buck” in virtual
memory management
• VMware
– Does not trust guest information
• Building a “black box” solution
– Started with memory swapping, and digging out of
the hole
33. Dynamic Memory, not Overcommit
• Overloaded Term
– Page Sharing
– Second Level Paging
– Balloon Type Mechanisms
• No one wants to overcommit their resource
– You don’t overcommit other resources (really – you do
not)
– VMware does not want you to overcommit memory
(really)
• DM treats memory like we treat CPU resources
– Dynamically schedulable resource
34. External Page Sharing
• How it works:
1. Hash all memory and store it in a table…
2. Identify the common hashes and then…
3. Perform a bit by bit comparison
• What VMware doesn’t tell you…
– Page Sharing not dynamic
– Can take hours to share pages
– The largest benefit are zero pages
– Doesn’t work with large pages
35. Second Level Paging
• Many problems:
– Swapping Guest Kernel Resources
– Double Paging
– Disks are slow
• But it always works…
36. Other Techniques
• Guest directed page sharing
• Memory compression
• And on…
• We will continue to invest here and work on identifying
the best techniques for customer work loads
38. Test the beta – and talk to us!
• Try Dynamic Memory out – for both server and desktop
environments
– Let us know how DM is working for you
– Let us know if you think we have something wrong
39. More Resources
Virtualization @ Microsoft:
http://www.microsoft.com/virtualization
Hyper-V on TechNet:
http://technet.microsoft.com/library/cc753637(WS.10).aspx
Virtualization Team Blog:
http://blogs.technet.com/b/virtualization/
http://blogs.msdn.com/b/virtual_pc_guy
40. Source Info
www.microsoft.com/teched www.microsoft.com/learning
http://microsoft.com/technet http://microsoft.com/msdn
41. Hyper-V and Dynamic Memory in Depth
Dr. Eduardo Castro Martínez
Microsoft MVP
ecastro@mswindowscr.org
http://comunidadwindows.org
http://ecastrom.blogspot.com
