[RFC patch 11/41] ltt-relay: cache pages address

Mathieu Desnoyers
2009-03-05T23:32:37Z

[-- Attachment #1: lttng-optimize-write-to-page-function-cache-page-address.patch --]
[-- Type: text/plain, Size: 3197 bytes --]

page_address is not fast in some systems,
we should cache it.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---
include/linux/ltt-relay.h | 4 ++--
ltt/ltt-relay-alloc.c | 10 +++++-----
2 files changed, 7 insertions(+), 7 deletions(-)

Index: linux-2.6-lttng/include/linux/ltt-relay.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/ltt-relay.h 2009-03-05 16:07:47.000000000 -0500
+++ linux-2.6-lttng/include/linux/ltt-relay.h 2009-03-05 16:07:47.000000000 -0500
@@ -34,6 +34,7 @@ struct rchan_buf;

struct buf_page {
struct page *page;
+ void *virt; /* page address of the struct page */
size_t offset; /* page offset in the buffer */
struct list_head list; /* buffer linked list */
};
@@ -286,8 +287,7 @@ static inline int ltt_relay_write(struct

page = ltt_relay_cache_page(buf, &buf->wpage, page, offset);
pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
- ltt_relay_do_copy(page_address(page->page)
- + (offset & ~PAGE_MASK), src, pagecpy);
+ ltt_relay_do_copy(page->virt + (offset & ~PAGE_MASK), src, pagecpy);

if (unlikely(len != pagecpy))
_ltt_relay_write(buf, offset, src, len, page, pagecpy);
Index: linux-2.6-lttng/ltt/ltt-relay-alloc.c
===================================================================
--- linux-2.6-lttng.orig/ltt/ltt-relay-alloc.c 2009-03-05 16:07:47.000000000 -0500
+++ linux-2.6-lttng/ltt/ltt-relay-alloc.c 2009-03-05 16:07:47.000000000 -0500
@@ -54,6 +54,7 @@ static int relay_alloc_buf(struct rchan_
goto depopulate;
}
list_add_tail(&buf_page->list, &buf->pages);
+ buf_page->virt = page_address(buf_page->page);
buf_page->offset = (size_t)i << PAGE_SHIFT;
set_page_private(buf_page->page, (unsigned long)buf_page);
if (i == 0) {
@@ -529,8 +530,8 @@ void _ltt_relay_write(struct rchan_buf *

page = ltt_relay_cache_page(buf, &buf->wpage, page, offset);
pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
- ltt_relay_do_copy(page_address(page->page)
- + (offset & ~PAGE_MASK), src, pagecpy);
+ ltt_relay_do_copy(page->virt
+ + (offset & ~PAGE_MASK), src, pagecpy);
} while (unlikely(len != pagecpy));
}
EXPORT_SYMBOL_GPL(_ltt_relay_write);
@@ -556,8 +557,7 @@ int ltt_relay_read(struct rchan_buf *buf
for (;;) {
page = ltt_relay_cache_page(buf, &buf->rpage, page, offset);
pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
- memcpy(dest, page_address(page->page) + (offset & ~PAGE_MASK),
- pagecpy);
+ memcpy(dest, page->virt + (offset & ~PAGE_MASK), pagecpy);
len -= pagecpy;
if (likely(!len))
break;
@@ -610,7 +610,7 @@ void *ltt_relay_offset_address(struct rc
if (offset < page->offset || offset >= page->offset + PAGE_SIZE)
buf->hpage[odd] = page = buf->wpage;
page = ltt_relay_cache_page(buf, &buf->hpage[odd], page, offset);
- return page_address(page->page) + (offset & ~PAGE_MASK);
+ return page->virt + (offset & ~PAGE_MASK);
}
EXPORT_SYMBOL_GPL(ltt_relay_offset_address);