While studying the file ufs_readwrite.c, I see routines like uiomoveco() that calls vm_uiomove() in vm_map.c. I am almost sure that these are new in FreeBSD 3.x. The comment in ffs_read() says "not a VM based I/O requests" == "not headed for the buffer cache". This does not make sense to me although I understand something about VMIO buffers and non-VMIO buffers. I hope someone can explain the basic ideas of I/O optimization with VM object (relating to the OBJ_OPT flag and the global variable vfs_ioopt) so that I can understand the code easier.
Any help is appreciated. -------------------------------------------------- Zhihui Zhang. Please visit http://www.freebsd.org -------------------------------------------------- To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-hackers" in the body of the message
