Hack to get dvd-burning at 8x (instead of 3x) with ide-cd (2.6.11)

Hi,

I'd like to receive comments/guide-lines about a hack I made to the 2.6.11 kernel to improve DVD-burning speed (using growisofs.)

The basic idea is the 16-pages pipe between mkisofs and growisofs is too small for DVD burning (typical 4GB of data.)

In the hack, pipe_new will simply check for, if privileges permitted, the enviroment variable
PIPE_MAX_ORDER to see if a (much) longer pipe is requested.

This hack enable me to burn DVD at 8X (instead of 3X) on my old P3-450MHz (with growisofs and mkisofs running at SCHED_FIFO.)

Linh Dang

@@ -21,7 +21,6 @@ struct pipe_buf_operations {
 struct pipe_inode_info {
 	wait_queue_head_t wait;
 	unsigned int nrbufs, curbuf;
-	struct pipe_buffer bufs[PIPE_BUFFERS];
 	struct page *tmp_page;
 	unsigned int start;
 	unsigned int readers;

@@ -31,6 +30,8 @@ struct pipe_inode_info {
 	unsigned int w_counter;
 	struct fasync_struct *fasync_readers;
 	struct fasync_struct *fasync_writers;
+        unsigned max_nr_buffers;
+	struct pipe_buffer bufs[0];
 };
 
 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual

This problem is likely caused by limited filesystem and/or hard disk performance, not a slow CPU. You don't need a kernel patch to get a bigger buffer though. See:

        http://article.gmane.org/gmane.comp.audio.cd-record/2253

Peter Osterlund - [email protected]
http://web.telia.com/~u89404340