Unified file cache

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Below are written transcripts for this Webcast in two parts:

The Webcast describes the unified file caches in HP-UX 11i v3. The unified file cache integrates the page cache and buffer cache to provide coherency for file access. Prior to HP-UX 11i v3, the file system used the buffer cache to cache file data and the mmap() interface used the page cache to cache file data. If an application accesses the file using both read()/write() system calls and mmap() simultaneously, then HP-UX did not guarantee coherency since the same data resides in two caches. With a unified file cache, coherency can be achieved. Also, we have implemented a unified  architecture for accessing file data and provided kernel interfaces that would be used by both the file system for read() and write() system calls and VM for mmap(). These interfaces should also ease the port of NFS (ONC 2.3) and third party file systems from Solaris.

The content of this Webcast is delivered according to the following agenda:

• Motivation
• UFC architecture
• Key features
• Application and file system impact
• Performance data
• Summary

Saleem Mohideen joined HP in August, 1988. He has been working in the HP-UX kernel group for over 13 years. He is a system architect for the HP-UX Virtual Memory subsystem. He has made significant contributions to the HP-UX Virtual Memory subsystem.

Saleem Mohideen was the technical lead for the Unified File Cache project. He helped lead the project as well as made significant code changes to implement a unified file cache.

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