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| author | Jens Axboe <axboe@suse.de> | 2006-05-01 22:02:05 +0400 |
|---|---|---|
| committer | Jens Axboe <axboe@suse.de> | 2006-05-01 22:02:05 +0400 |
| commit | f6762b7ad8edd6abc802542ce845d3bc8adcb92f (patch) | |
| tree | c941aaf7295f8efecaf42aa86112649b9b6f23a9 /include/linux | |
| parent | e27dedd84c119e2f7af54fcde3293be5ad812103 (diff) | |
| download | linux-f6762b7ad8edd6abc802542ce845d3bc8adcb92f.tar.xz | |
[PATCH] pipe: enable atomic copying of pipe data to/from user space
The pipe ->map() method uses kmap() to virtually map the pages, which
is both slow and has known scalability issues on SMP. This patch enables
atomic copying of pipe pages, by pre-faulting data and using kmap_atomic()
instead.
lmbench bw_pipe and lat_pipe measurements agree this is a Good Thing. Here
are results from that on a UP machine with highmem (1.5GiB of RAM), running
first a UP kernel, SMP kernel, and SMP kernel patched.
Vanilla-UP:
Pipe bandwidth: 1622.28 MB/sec
Pipe bandwidth: 1610.59 MB/sec
Pipe bandwidth: 1608.30 MB/sec
Pipe latency: 7.3275 microseconds
Pipe latency: 7.2995 microseconds
Pipe latency: 7.3097 microseconds
Vanilla-SMP:
Pipe bandwidth: 1382.19 MB/sec
Pipe bandwidth: 1317.27 MB/sec
Pipe bandwidth: 1355.61 MB/sec
Pipe latency: 9.6402 microseconds
Pipe latency: 9.6696 microseconds
Pipe latency: 9.6153 microseconds
Patched-SMP:
Pipe bandwidth: 1578.70 MB/sec
Pipe bandwidth: 1579.95 MB/sec
Pipe bandwidth: 1578.63 MB/sec
Pipe latency: 9.1654 microseconds
Pipe latency: 9.2266 microseconds
Pipe latency: 9.1527 microseconds
Signed-off-by: Jens Axboe <axboe@suse.de>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/pipe_fs_i.h | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index b8aae1fc5185..4c054491e38e 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -5,7 +5,8 @@ #define PIPE_BUFFERS (16) -#define PIPE_BUF_FLAG_LRU 0x01 +#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */ +#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */ struct pipe_buffer { struct page *page; @@ -28,8 +29,8 @@ struct pipe_buffer { */ struct pipe_buf_operations { int can_merge; - void * (*map)(struct pipe_inode_info *, struct pipe_buffer *); - void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *); + void * (*map)(struct pipe_inode_info *, struct pipe_buffer *, int); + void (*unmap)(struct pipe_inode_info *, struct pipe_buffer *, void *); int (*pin)(struct pipe_inode_info *, struct pipe_buffer *); void (*release)(struct pipe_inode_info *, struct pipe_buffer *); int (*steal)(struct pipe_inode_info *, struct pipe_buffer *); @@ -64,8 +65,8 @@ void free_pipe_info(struct inode * inode); void __free_pipe_info(struct pipe_inode_info *); /* Generic pipe buffer ops functions */ -void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *); -void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *); +void *generic_pipe_buf_map(struct pipe_inode_info *, struct pipe_buffer *, int); +void generic_pipe_buf_unmap(struct pipe_inode_info *, struct pipe_buffer *, void *); void generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *); int generic_pipe_buf_pin(struct pipe_inode_info *, struct pipe_buffer *); |