Re: 2.6.9-rc1-mm3

[Peter Osterlund <petero2@telia.com>]

Andrew Morton <akpm@osdl.org> writes:

> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.9-rc1/2.6.9-rc1-mm3/
> 
> - Added the m32r architecture.  Haven't looked at it yet.
> 
> - Status update on various large patches in -mm:
> 
>   - The packet-writing code is awaiting resolution of the
>     abuse-of-elevator-fields problem.

It doesn't abuse the elevator fields any more. That was fixed by the
packet-writing-avoid-bio-hackery patch which is already in -mm.

One problem that does remain though, is that when dumping huge amounts
of data to a CD or DVD disc (so that you get memory pressure), the
effective writing speed of other block devices (like IDE hard disks)
is reduced to the same speed as the packet device.

I have posted a patch that fixes this problem by limiting the amount
of writeback data in the packet driver, but unfortunately it makes the
effective writing speed of the packet device suffer a lot. The proper
fix is probably to improve the filesystem and/or VM code to start I/O
operations in sequential order a lot more often than it currently
does.

-- 
Peter Osterlund - petero2@telia.com
http://w1.894.telia.com/~u89404340