Windows Vista: System Performance Enhancements Simon Martyn Infrastructure Specialist The IQ Business Group Technology Services Division

Agenda Current performance limitations Optimizing Memory Use – SuperFetch™ Avoiding the Disk Bottleneck – ReadyBoost™ – ReadyDrive™ Supporting infrastructure – Low-priority I/O – Diagnostic tools

What Causes Inconsistent Responsiveness? Poor memory content – Performance erodes over time The application has not run recently Background applications have swept through memory – Transitions affect memory After boot or hibernate After Fast User Switch After lunch or big application Random/blocking disk operations – Page faults – Program loads – Disk spin up time – Disk seeks

The Seek Problem Drive industry continues to deliver impressive data rate, rotation and interface speed improvements – ATA/33  ATA/66  ATA/100  SATA – 4200RPM  5400RPM  7200RPM  10000RPM – 2 MB  8 MB  16 MB – Result: Sequential IO rates of 80 MB/s+ At that rate, 1 GB of RAM fully populated in ~12.8sec Seek times improving, but not as significantly – 3.5” Desktop drive avg seek ~10 mSec – 2.5” Mobile drives ~12.5 mSec – Much better when hitting the track buffer – Result: Random IO rate limited to an effective 1MB/sec At that rate, populating 1GB of RAM takes ~1024sec!

.data pages MFT Entry Directory Entry PE Header.text pages DramCache DLLs On Disk

The Seek Problem 50% of MobileMark 2005 I/Os are 4 KB and random Files and structured files – A single DLL is generally 5 to 6 Disk Locations (min) Directory, MFT Entry, and other File System Metadata PE Hdr page,.text pages,.data pages,.rsrc pages, etc. – Programs like Internet Explorer, Adobe Reader, or Outlook use over 100 DLLs Reliability and durability – Logging, Transactions, Application Temp Files A simple Registry Write can require 5 to 6 Random and Ordered Disk Writes Synchronous blocking nature of page faults – Code pages, Stack pages, and Heap pages can all be faulted upon – Hard to develop Asynchronous Client applications

What Do Users See? Slow state transitions Decreased application responsiveness under memory pressure Slower program launch

How Does Microsoft Windows Vista Help? Provides new innovations in memory management Avoids hitting the disk where possible Prioritizes I/O when you do hit the disk Contains new diagnostic tools

Smart Memory Management

Internet Explorer Memory OS Startup Apps Microsoft Word Outlook Photo Editor Disk free memory memory cache Current Memory Management

SuperFetch SuperFetch is a breakthrough in memory management – Optimizes based on usage patterns over time – Takes into account frequency of page usage, usage of page in context of other pages in memory – Adapts to memory usage patterns, including complex usage scenarios – Can differentiate based on user, time and day of week

Internet Explorer Memory OS Startup Apps Microsoft Word Outlook Photo Editor Disk memory cache Photo Editor SuperFetch

SuperFetch is proactive and resilient – Smart about getting the right content into memory early – Keeps correct content in memory

Internet Explorer Idle Tasks Microsoft Word Outlook Idle Tasks Internet Explorer Idle Tasks Outlook Idle Tasks MS Word Idle Tasks OS Startup Apps Photoshop Traditional OS Startup Apps Photoshop memory cache OS Startup Apps Photoshop Superfetch OS Startup Apps Photoshop Keeping The Right Data In Memory

SuperFetch SuperFetch is efficient – Uses low priority I/O for pre-fetching and pre-population SuperFetch manages RAM and cache memory

Avoid The Disk Bottleneck

ReadyBoost Flash memory serves as a cache for SuperFetch – External USB keys, SD cards, Compact Flash, internal PCIe cards Allows fast reads to satisfy page faults when page is not in main memory – Up to 10x faster than random HDD reads Caches data proactively based on user activity

ReadyBoost Properties Reliable – Write-through cache allows user to remove device at any time – Device wear is not an issue Unique write gathering algorithm optimizes performance and wear patterns Projected life of 19.4 – 1823 years depending on device size and variant (10K or 100K write-erase cycles) Secure – Data is encrypted using AES-128 Efficient – Data is compressed by a factor of 1.8X to 2.3X

ReadyDrive Hybrid Hard Disk A Nonvolatile cache (NV Cache) is added to the hard disk drive – Allows data to be read and written while platter is spun down – Data in cache persisted when powered down – SuperFetch provides efficient cache utilization Dram Cache NV Cache Up to 90% Power Saving over conventional HDD SATA or PATA Interface Read and Write while spindle is stopped

MFT Entry Directory Entry DramCache.data pages PE Header.text pages DLLs On Disk

MFT Entry Directory Entry PE Header.text pages Dram Cache NV Cache.data pages DLLs On ReadyDrive H-HDD

NV Cache contents Cached writes Boot/resume sectors Sectors pinned by OEMs Read cache

ReadyDrive Benefits Performance – Faster Boot – Faster Hibernate/Resume – Performance improvement from minimizing disk seeks and enabling more IOs per second Power Savings/Battery Life – Windows Vista can reduce HDD power consumption of typical 2.5” HDD by 70-90% when operating on battery by keeping magnetic platter spun down most of the time Reliability improvements – Vibration or impact during writes not a problem with NV memory Reduced noise

ReadyDrive ATA Command Set A new ATA command set has been specified by Microsoft, HDD manufacturers, and industry partners which enables rich management of the NV Cache Single ATA command with sub-commands – Identify hybrid hard disk functionality – Add/Remove LBAs from NV Cache “pinned set” – Query NV Cache pinned set – Enter/Leave power saving mode – Etc. Accepted by T13 for standardization in the ATA 8 specification Opportunity for innovation by device and host moving forward

ReadyBoost And ReadyDrive System Memory HDD Platter Read Cache ReadyBoost Write Cache OEM Pinning Boot Data Read Cache ReadyDrive NVRAM RAM Magnetic

ReadyBoost And ReadyDrive ReadyBoost and ReadyDrive are complementary technologies Both powered by SuperFetch ReadyDrive – Helps state transitions – Can pin and accelerate some data – Improves reliability – Saves power ReadyBoost – Large read cache – Relieves memory pressure

Prioritized I/O

Low-priority I/O Why low-priority I/O? – Developers have long been able to throttle CPU usage by setting thread priorities – Low CPU usage can still slow down the system – With Windows Vista, developers can set I/O priorities Low-priority I/O applications – SuperFetch – Search indexing – Windows Defender – Disk defrag software – Startup applications

Using Low-priority I/O Call SetThreadPriority with THREAD_BACKGROUND_MODE_BEGIN Call SetProcessPriorityClass with PROCESS_BACKGROUND_MODE_BEGIN

Diagnostic Tools

Current Tool Limitations Repeatability – Often times, issues are non-deterministic Proactivity – Event logs are a good start but not end-user friendly

Performance Analyzer Windows Diagnostic Infrastructure System Event Log CKCL - ETW Kernel Events Performance Diagnostics Architecture Performance Tuning And Diagnostics Lower the cost for diagnosing performance problems – Easier diagnosis and resolution of performance problems Leverages data within the Circular Kernel Context Logger (CKCL) – Provides a record of recent system activity – Automated analysis applied for defined scenarios – Analysis results written to System Event Log

Vista Performance Benefits Windows Vista Delivers Consistent Performance – Improved power transitions – Consistent responsiveness, even in adverse conditions Windows Vista uses innovative technology to address the biggest user issues – SuperFetch is a breakthrough in memory management – ReadyDrive Hybrid Hard Disks provide reliability, battery, and performance benefits – ReadyBoost enabled flash improves responsiveness without needing to add more RAM – Low priority I/O prevents background applications from affecting user actions Windows Vista has improved diagnostic infrastructure – Circular Kernel Context Logger (CKCL)

Thank you to our Partners for their support of TechDays 2007