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Improving the overall system performance by enhancing the head ahead alogithrm for Encrypted filesystem pages Disclosure Number: IPCOM000235065D
Publication Date: 2014-Feb-26
Document File: 9 page(s) / 78K

Publishing Venue

The Prior Art Database


This article is about a system for improving the overall system performance by enhancing the Read ahead algorithm for Encrypted File system pages.

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This is the abbreviated version, containing approximately 31% of the total text.

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Improving the overall system performance by enhancing the head ahead alogithrm for Encrypted filesystem pages

Overview of EFS:
The Encrypted Files System enables individual users on the system to encrypt their data on J2 file system through their individual key stores. A key is associated to each user. These keys are stored in cryptographically protected key store and upon successful login, the user's keys are loaded into the kernel and associated with the

processes credentials. Later on, when the process needs to open an EFS-protected file, these credentials are tested and if a key matching the file protection is found, the process is able to decrypt the file key and therefore the file content

EFS pages always gets in disk with encrypted format ,and when it gets loaded from disk to memory it has to be decrypted and gets stored in memory in a clear format to get accessed by authorised users.

overview of Read ahead algorithm: -----------------------------------------------------

This is used to enhance the performance of a process which requires a files to be read in a sequential order by loading all the required pages in advance which will be needed in near future..

A read ahead request is an I/O request to prefetch multiple pages in the buffer cache asynchronously in anticipation that these pages will be needed in near future.

Problem with read ahead algorithm in case of EFS files: ----------------------------------------------------------------------------

Basically EFS pages always resides in encrypted format in disk and gets loaded into memory in a clear format by going through the process of decryption.

As Read ahead algorithm reads the pages in advance,in this case of EFS, this algorithm loads all the required EFS pages into memory in advance in a clear format by going through process of decryption as considering those pages will be used by near future..If those pages loaded in advance by read ahead algorithm will not be getting used by the process anymore,then the cost involved in this process of decryption of those EFS pages while loading into memory and also the CPU cycles involved will be of no use which inturn degrading the performance of entire system .

In this idea the problem mentioned above have been solved by proposed way which has been described below.

Core idea lies by supporting different modes at the time of opening EFS files i.e


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PAGE_AHEAD_NORMAL :means Read Ahead algorithm works in a default way as it works for other normal files.

PAGE_AHEAD__MINIMAL:works in such a way that minimum number of EFS pages will be read in advance from disk to memory ( on which

Our dsiclosure mainly focuses on how the minimum number of EFS pages will be read in adavnce for improval of system performance.. )

PAGE_AHEAD_NIL: where the user chooses not to have Read Ahead algorithm for EFS files based upon the requirement.