Re: Linux 2.6.17-rc2

[Nick Piggin <nickpiggin@yahoo.com.au>]

Linh Dang wrote:
> Jens Axboe <axboe@suse.de> wrote:

>>DVD burning probably isn't a good splice fit, since you need to do
>>more than actually just point the device at the data. SG_IO is
>>already zero-copy as it maps the user data into the kernel without
>>copying, so there's very little room for improvement there to begin
>>with.
> 
> 
> DVD burning on linux is mostly:
> 
>         mkisofs .... | growisofs ....
> 
> Ideally, on mkisofs side, we'd be able to:
> 
>   - write some data/padding into the pipe
>   - splice a HUGE file into the pipe
>   - write some data/padding into the pipe
>   - splice a HUGE file into the pipe
>   ...
> 
> On growisofs side, we'd be able to:
> 
>   - send some commands
>   - splice N MBs of data from the pipe to the driver
>   - send some commands
>   - splice M MBs of data from the pipe to the driver
>   ...
> 
> What'd be nice is an ioctl to change the size of the pipe between
> mkisofs and growisofs.

I don't see why the pipe buffers would be a problem though. It isn't
like you've lost any of the pagecache buffering (eg. from readahead)
or the application level buffering.

-- 
SUSE Labs, Novell Inc.
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