M
MICHAEL
http://blogs.technet.com/markrussinovich/archive/2008/02/04/2826167.aspx
by Mark Russinovich
Inside Vista SP1 File Copy Improvements
Windows Vista SP1 includes a number of enhancements over the original Vista release in the
areas of application compatibility, device support, power management, security and reliability.
You can see a detailed list of the changes in the Notable Changes in Windows Vista Service Pack
1 whitepaper that you can download here. One of the improvements highlighted in the document is
the increased performance of file copying for multiple scenarios, including local copies on the
same disk, copying files from remote non-Windows Vista systems, and copying files between SP1
systems. How were these gains achieved? The answer is a complex one and lies in the changes to
the file copy engine between Windows XP and Vista and further changes in SP1. Everyone copies
files, so I thought it would be worth taking a break from the "Case of." posts and dive deep
into the evolution of the copy engine to show how SP1 improves its performance.
Copying a file seems like a relatively straightforward operation: open the source file, create
the destination, and then read from the source and write to the destination. In reality,
however, the performance of copying files is measured along the dimensions of accurate progress
indication, CPU usage, memory usage, and throughput. In general, optimizing one area causes
degradation in others. Further, there is semantic information not available to copy engines
that could help them make better tradeoffs. For example, if they knew that you weren't planning
on accessing the target of the copy operation they could avoid caching the file's data in
memory, but if it knew that the file was going to be immediately consumed by another
application, or in the case of a file server, client systems sharing the files, it would
aggressively cache the data on the destination system.
continued.......
http://blogs.technet.com/markrussinovich/archive/2008/02/04/2826167.aspx
-Michael
by Mark Russinovich
Inside Vista SP1 File Copy Improvements
Windows Vista SP1 includes a number of enhancements over the original Vista release in the
areas of application compatibility, device support, power management, security and reliability.
You can see a detailed list of the changes in the Notable Changes in Windows Vista Service Pack
1 whitepaper that you can download here. One of the improvements highlighted in the document is
the increased performance of file copying for multiple scenarios, including local copies on the
same disk, copying files from remote non-Windows Vista systems, and copying files between SP1
systems. How were these gains achieved? The answer is a complex one and lies in the changes to
the file copy engine between Windows XP and Vista and further changes in SP1. Everyone copies
files, so I thought it would be worth taking a break from the "Case of." posts and dive deep
into the evolution of the copy engine to show how SP1 improves its performance.
Copying a file seems like a relatively straightforward operation: open the source file, create
the destination, and then read from the source and write to the destination. In reality,
however, the performance of copying files is measured along the dimensions of accurate progress
indication, CPU usage, memory usage, and throughput. In general, optimizing one area causes
degradation in others. Further, there is semantic information not available to copy engines
that could help them make better tradeoffs. For example, if they knew that you weren't planning
on accessing the target of the copy operation they could avoid caching the file's data in
memory, but if it knew that the file was going to be immediately consumed by another
application, or in the case of a file server, client systems sharing the files, it would
aggressively cache the data on the destination system.
continued.......
http://blogs.technet.com/markrussinovich/archive/2008/02/04/2826167.aspx
-Michael