On Tue, 2005-03-01 at 10:24 -0800, Bryan Henderson wrote: > One thing that's implicit in your reasons for wanting to be in the kernel > is that you've chosen to exploit the kernel's page cache. As a user of > the page cache, you have more control from inside the kernel than from > user space. The page cache was designed to be fundamentally invisible to > user space. > > A pure user space implementation of an ISCSI target would use process > virtual memory for a cache and manage it itself. It would access the > storage with direct I/O.
why would it use direct I/O ? Direct I/O would be really stupid for such a thing to use since that means there's no caching going on *at all*. You want to *use* the kernel pagecache as much as you can. You do so by using mmap and such, and msync to force content to disk. That uses the kernel pagecache to the maximum extend, while not having to bother with knowing the intimate details of the implementation thereof, which a kernel side implementation would be involved in. (if it wasnt and only used highlevel functions, then you might as well do the same in userspace after all) - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
