Make pipe data structure be a circular list of pages, rather than

a circular list of one page.

This improves pipe throughput, and allows us to (eventually)
use these lists of page buffers for moving data around efficiently.

1 files changed, 10 insertions, 9 deletions

diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index ba955acdbb01..1e73dd8fd258 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -2,10 +2,18 @@
 #define _LINUX_PIPE_FS_I_H
 
 #define PIPEFS_MAGIC 0x50495045
+
+#define PIPE_BUFFERS (16)
+
+struct pipe_buffer {
+	struct page *page;
+	unsigned short offset, len;
+};
+
 struct pipe_inode_info {
 	wait_queue_head_t wait;
-	char *base;
-	unsigned int len;
+	unsigned int nrbufs, curbuf;
+	struct pipe_buffer bufs[PIPE_BUFFERS];
 	unsigned int start;
 	unsigned int readers;
 	unsigned int writers;
@@ -33,13 +41,6 @@ struct pipe_inode_info {
 #define PIPE_FASYNC_READERS(inode)     (&((inode).i_pipe->fasync_readers))
 #define PIPE_FASYNC_WRITERS(inode)     (&((inode).i_pipe->fasync_writers))
 
-#define PIPE_EMPTY(inode)	(PIPE_LEN(inode) == 0)
-#define PIPE_FULL(inode)	(PIPE_LEN(inode) == PIPE_SIZE)
-#define PIPE_FREE(inode)	(PIPE_SIZE - PIPE_LEN(inode))
-#define PIPE_END(inode)	((PIPE_START(inode) + PIPE_LEN(inode)) & (PIPE_SIZE-1))
-#define PIPE_MAX_RCHUNK(inode)	(PIPE_SIZE - PIPE_START(inode))
-#define PIPE_MAX_WCHUNK(inode)	(PIPE_SIZE - PIPE_END(inode))
-
 /* Drop the inode semaphore and wait for a pipe event, atomically */
 void pipe_wait(struct inode * inode);