The patch titled
cache pipe buf page address for non-highmem arch
has been removed from the -mm tree. Its filename was
cache-pipe-buf-page-address-for-non-highmem-arch.patch
This patch was dropped because it had testing failures
------------------------------------------------------
Subject: cache pipe buf page address for non-highmem arch
From: "Ken Chen" <kenchen@xxxxxxxxxx>
It is really sad that we always call kmap and friends for every pipe buffer
page on 64-bit arch that doesn't use HIGHMEM, or on configuration that
doesn't turn on HIGHMEM.
The effect of calling kmap* is visible in the execution profile when pipe
code is being stressed. It is especially true on amd's x86-64 platform
where kmap() has to traverse through numa node index calculation in order
to convert struct page * to kernel virtual address. It is fairly pointless
to perform that calculation repeatly on system with no highmem (i.e.,
64-bit arch like x86-64). This patch caches kernel pipe buffer page's
kernel vaddr to speed up pipe buffer mapping functions.
There is another suboptimal block in pipe_read() where wake_up is called
twice. I think it was an oversight since in pipe_write(), it looks like it
is doing the right thing.
Signed-off-by: Ken Chen <kenchen@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/pipe.c | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)
diff -puN fs/pipe.c~cache-pipe-buf-page-address-for-non-highmem-arch fs/pipe.c
--- a/fs/pipe.c~cache-pipe-buf-page-address-for-non-highmem-arch
+++ a/fs/pipe.c
@@ -21,6 +21,21 @@
#include <asm/uaccess.h>
#include <asm/ioctls.h>
+#ifdef CONFIG_HIGHMEM
+#define pipe_kmap kmap
+#define pipe_kmap_atomic kmap_atomic
+#define pipe_kunmap kunmap
+#define pipe_kunmap_atomic kunmap_atomic
+#else /* CONFIG_HIGHMEM */
+static inline void *pipe_kmap(struct page *page)
+{
+ return (void *) page->private;
+}
+#define pipe_kmap_atomic(page, type) pipe_kmap(page)
+#define pipe_kunmap(page) do { } while (0)
+#define pipe_kunmap_atomic(page, type) do { } while (0)
+#endif
+
/*
* We use a start+len construction, which provides full use of the
* allocated memory.
@@ -169,10 +184,10 @@ void *generic_pipe_buf_map(struct pipe_i
{
if (atomic) {
buf->flags |= PIPE_BUF_FLAG_ATOMIC;
- return kmap_atomic(buf->page, KM_USER0);
+ return pipe_kmap_atomic(buf->page, KM_USER0);
}
- return kmap(buf->page);
+ return pipe_kmap(buf->page);
}
void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
@@ -180,9 +195,9 @@ void generic_pipe_buf_unmap(struct pipe_
{
if (buf->flags & PIPE_BUF_FLAG_ATOMIC) {
buf->flags &= ~PIPE_BUF_FLAG_ATOMIC;
- kunmap_atomic(map_data, KM_USER0);
+ pipe_kunmap_atomic(map_data, KM_USER0);
} else
- kunmap(buf->page);
+ pipe_kunmap(buf->page);
}
int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
@@ -316,6 +331,7 @@ redo:
if (do_wakeup) {
wake_up_interruptible_sync(&pipe->wait);
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
+ do_wakeup = 0;
}
pipe_wait(pipe);
}
@@ -423,6 +439,8 @@ redo1:
ret = ret ? : -ENOMEM;
break;
}
+ page->private = (unsigned long)
+ page_address(page);
pipe->tmp_page = page;
}
/* Always wake up, even if the copy fails. Otherwise
@@ -438,16 +456,16 @@ redo1:
iov_fault_in_pages_read(iov, chars);
redo2:
if (atomic)
- src = kmap_atomic(page, KM_USER0);
+ src = pipe_kmap_atomic(page, KM_USER0);
else
- src = kmap(page);
+ src = pipe_kmap(page);
error = pipe_iov_copy_from_user(src, iov, chars,
atomic);
if (atomic)
- kunmap_atomic(src, KM_USER0);
+ pipe_kunmap_atomic(src, KM_USER0);
else
- kunmap(page);
+ pipe_kunmap(page);
if (unlikely(error)) {
if (atomic) {
_
Patches currently in -mm which might be from kenchen@xxxxxxxxxx are
type-cast-clean-up-for-find_next_zero_bit.patch
cache-pipe-buf-page-address-for-non-highmem-arch.patch
-
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