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Results of the Andrew benchmark


The results of the Andrew benchmark are presented in table gif.

Table: Results of the Andrew benchmark

The results of the two first passes show that Linux benefits from its asynchronous metadata I/O. In passes 1 and 2, directories and files are created and BSD synchronously writes inodes and directory entries. There is an anomaly, though: even in asynchronous mode, the performance under BSD is poor. We suspect that the asynchronous support under FreeBSD is not fully implemented.

In pass 3, the Linux and BSD times are very similar. This is a big progress against the same benchmark run six months ago. While BSD used to outperform Linux by a factor of 3 in this test, the addition of a file name cache in the VFS has fixed this performance problem.

In passes 4 and 5, Linux is faster than FreeBSD mainly because it uses an unified buffer cache management. The buffer cache space can grow when needed and use more memory than the one in FreeBSD, which uses a fixed size buffer cache. Comparison of the Ext2fs and Xiafs results shows that the optimizations included in Ext2fs are really useful: the performance gain between Ext2fs and Xiafs is around 5-10 %.

Andrew Anderson
Thu Mar 7 22:36:29 EST 1996