As Zhihui Zhang wrote ... > > The value of MAXPHYS is chosen to be 64K for the maximum raw I/O transfer > size. I am wondering why it is not set larger. The maxcontig value of FFS > is default to be 16, which means 16*8192 or 128K bytes (twice as big as > 64K) . If we raise the value of MAXPHYS, we can put more data blocks of a > big file contiguously on the disk (perhaps even more than 16 blocks to > achieve better performance). Am I right? Is there any limit of the value > of MAXPHYS?
The 64kB limit is a limitation of older SCSI cards. My primary objective to have a > 64kB MAXPHYS is to have larger blocksizes on tape. Especially DLT drives love that ;-) | / o / / _ Arnhem, The Netherlands - Powered by FreeBSD - |/|/ / / /( (_) Bulte WWW : http://www.tcja.nl http://www.freebsd.org To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-hackers" in the body of the message
