Re: 2.6.9-rc1-mm3

[Andrew Morton]

Peter Osterlund <petero2@xxxxxxxxx> wrote:
>
> 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.

If you decrease /proc/sys/vm/dirty_ratio and dirty_background_ratio to much
smaller levels, does that fix things up? 

If so, we might be able to put some sort of per-queue override into your
queue's backing_dev_info.
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