On Wed, 2001-12-05 at 10:36, Roy Sigurd Karlsbakk wrote:
> Does XFS have any readahead setting on its own? I've tried the
> /proc/sys/vm/(max|min)-readahead setting in Linux without any success. I
> need somewhere between 4 and 16 MB readahead per file to be able to read
> a large number of large files concurrently, and to reduce seeks to a
The XFS read path is really the general linux read path, so the
readahead logic is the same for both. Take a look in mm/filemap.c
looks for MAX_READAHEAD - it is 31 pages, or 124K bytes, you could
probably change the algorithm and bump the maximum in here - however,
readahead just queues I/O to the block layer, the block layer has
its own maximum sizes for individual I/O requests. You may find
upping the readahead limit just pushes the problem down the stack
so to speak.
> Roy Sigurd Karlsbakk, MCSE, MCNE, CLS, LCA
> Computers are like air conditioners.
> They stop working when you open Windows.
Steve Lord voice: +1-651-683-3511
Principal Engineer, Filesystem Software email: lord@xxxxxxx