Re: Main CPU- I/O CPU interaction

From: Alan Cox
Date: Tue Jan 04 2005 - 19:02:08 EST


On Llu, 2005-01-03 at 22:27, Valdis.Kletnieks@xxxxxx wrote:
> What sort of I/O device processor is (a) supported by Linux *and* (b) filesystem
> aware? Unless it meets both criteria, the main CPU(s) will still have to do
> all the work of block allocation, inode creation, and all the rest of that
> stuff.

NetApp 8)

The offloading file system stuff has been proposed and kicked around and
failed repeatedly in different circles. What has had some success is
offloading layout so that the I/O device thinks in terms of

handle = allocate(blocks, near_this, and_this, ....)
data = read(handle, offset, len)
write(handle, offset, len, data)
free(handle)

type API's, allowing the storage subsystem to do physical
mirror/relocation/HSM in private.

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