Slide 1 Windows PC Accelerators Reporter ：吳柏良

Slide 2 Outline l Introduction l Windows SuperFetch l Windows ReadyBoost l Windows ReadyDrive l Conclusion

Slide 3 Introduction l Windows PC Accelerators are the mechanism used in Windows Vista to improve performance especially on I/O response time. l Ensuring Memory is well Utilized l SuperFetch ： an memory manager that analyzes usage pattern over time to optimize memory content l Avoiding the Disk Bottleneck l ReadyBoost Expanded Memory Devices ： support the use of flash storage devices to boost PC performance l ReadyDrive Hybrid Hard Drive ： support the use of hybrid hard drives (H-HDDs)

Slide 4 Poor Memory Contents l Typical Memory Pressure Scenario 1. Memory is populated with pages for Application A 2. Application B is loaded, pushing App A’s pages out 3. User switches back to Application A 4. Application A reloads pages as needed through Pagefaults, pushing out Application B’s pages 5. Repeat cycle…

Slide 5 Disk Seek Time Problem l Drive Industry Continues to Deliver Impressive Data Rate, Rotation and Interface Speed Improvements l ATA/33  ATA/66  ATA/100  SATA l 4200RPM  5400RPM  7200RPM  10000RPM l 2 MB  8 MB  16 MB l Result ： Sequential IO rates of 80 MB/s+ l At that rate, 1 GB of RAM fully populated in ~12.8sec l Seek Times Improving, but not as Significantly l 3.5” Desktop drive avg seek ~10 mSec l 2.5” Mobile drives ~12.5 mSec l Much better when hitting the track buffer… l Result ： Random IO rate limited to an effective 1MB/sec l At that rate, populating 1GB of RAM takes ~1024sec!

Slide 6 Disk Seek Time Problem l 50% of MobileMark 2005 I/Os are 4 KB and Random l Files and Structured Files l A single DLL is generally 5 to 6 Disk Locations (min) l Directory, MFT Entry, and other File System Metadata l Programs like Internet Explorer, Adobe Reader, or Outlook use over 100 DLLs l Logging, Transactions, Application Temp Files l A simple Registry Write can require 5 to 6 Random and Ordered Disk Writes

Slide 7 Outline l Introduction l Windows SuperFetch l Windows ReadyBoost l Windows ReadyDrive l Conclusion

Slide 8 Windows SuperFetch l SuperFetch analyzes memory usage patterns to determine the optimal memory content. l SuperFetch uses a lightweight, sophisticated tracking algorithm to determine which pages a user uses most frequently. l When the PC has free physical memory, SuperFetch places candidate pages into memory to make the PC more responsive. l SuperFetch manages both RAM and cache memory.

Slide 9 Outline l Introduction l Windows SuperFetch l Windows ReadyBoost l Windows ReadyDrive l Conclusion

Slide 10 Windows ReadyBoost l ReadyBoost supports the use of nonvolatile flash storage devices to boost system performance. l Allows fast reads to satisfy page faults when page is not in main memory and significantly outperforms disk in random reads by avoiding the rotational and seek latencies.

Slide 11 Windows ReadyBoost l Write-through cache allows user to remove device at any time l Secure l Data is encrypted using AES 128bit crypto l Efficient l Data is compressed by a factor of 1.8X to 2.3X

Slide 12 Windows ReadyBoost l Using a simulated workload on a PC running Windows Vista ReadyBoost Capacity Time to complete workload (s) Percent Improvement 0 MB MB MB MB

Slide 13 Implement Consideratins l Flash Performance l 5 MB/s for random 4K reads l 3 MB/s for random 512K writes l Flash Capacity l 3:1 ratio of ReadyBoost cache size to main memory size will realize optimal performance. l Flash Wear l Unique write gathering algorithm optimizes performance and wear patterns l Projected life of devices 19.4 – 1823 years depending on device size, variant, and usage patterns

Slide 14 Outline l Introduction l Windows SuperFetch l Windows ReadyBoost l Windows ReadyDrive l Conclusion

Slide 15 Windows ReadyDrive Up to 90% Power Saving when powered down Read and Write instantly while spindle stopped Read instantly even while spindle spinning for higher IO rate ATA Interface Disk comes ready in less than 1 second NV Cache DRAM Cache

Slide 16 Hybrid Hard Disk Boot And Resume l During shutdown or hibernate all the disk sectors needed to boot or resume are pinned into the NV cache l On next power on the BIOS POST runs and the disk is powered on but the spindle won’t be ready for 2-4 seconds l BIOS can read data from the NV cache and all boot process IO can be read from the NV Cache l Once the rotating media is ready IO can be satisfied by both NV Cache and rotating media for optimized read performance 2.5” HDD Hard Disk Controller NV Cache Motherboard DRAM ATA Controller Windows Vista OS

Slide 17 ReadyDrive System Startup l Hybrid HDD comes ready faster and fast BIOS POST reads from disk earlier l LBAs needed to start boot process are read from NV Cache before the magnetic spindle is ready l No seek times for data in NV Cache for the remainder of startup BIOS and Disk spin-up Read disk Read NV Cache Std HDD Hybrid HDD Read disk and NV Cache time

Slide 18 Power Saving Mode l SuperFetch buffers disk data in system DRAM to fulfill reads l Write IOs buffered in NV cache while disk is spun down l Disk spins up only when l Read cache miss l NV cache full l The disk spins-down and continues to use the NV cache 2.5” HDD Hard Disk Controller NV Cache Motherboard DRAM ATA Controller Windows Vista OS

Slide 19 Windows ReadyDrive l ReadyDrive is a hard disk drive with integrated nonvolatile flash memory that acts as a high- performance cache for writes and low-latency reads. l Performance l Faster boot and Resume from Hibernate l Faster and more consistent application launch l Reduced disk contention l Saves battery power l Increased system ruggedness and reliability

Slide 20 Windows ReadyDrive

Slide 21 Windows ReadyDrive Performance

Slide 22 Windows ReadyDrive Power Consumption

Slide 23 Implementatin Consideratins l ATA Command Set l Control what data is pinned for retention in the NV cache l Control the drive power mode l NV Cache Size l The NV cache size as large as 256 MB to 1 GB would be more effective. l NV Cache Performance > 4 MB/s4 KB random reads to a file pinned in the NV Cache > 4 MB/s4 KB random writes to a file pinned in the NV Cache > 8 MB/s64 KB sequential writes to a file pinned in the NV Cache > 16 MB/s64 KB sequential reads to a file pinned in the NV Cache

Slide 24 Conclusion l Microsoft introduces three mechanisms to improve system performance. l SuperFetch ： an memory manager that analyzes usage pattern over time to optimize memory content l ReadyDrive ： support the use of flash storage devices to boost PC performance l ReadyBoost ： support the use of hybrid hard drives (H-HDDs)

Slide 25 Reference l perfaccel.mspx perfaccel.mspx l b97017b-e28a-4bae-ba cf47d23cd/STO008_WH06.ppt b97017b-e28a-4bae-ba cf47d23cd/STO008_WH06.ppt l b97017b-e28a-4bae-ba cf47d23cd/CPA131_WH06.ppt b97017b-e28a-4bae-ba cf47d23cd/CPA131_WH06.ppt

Slide 26 Thank You!