On 05/20/2013 07:09 AM, Jan Friesse wrote:
Code for zero-copy in cpg does following mmaps:
- Mmap anonymous, private memory to some address (-> malloc)
- Mmap shared memory of fd to address returned by first mmap
(effectively shadows first mapping)
This is not necessary and only one mapping is needed.
This is a leftover cut and paste from IPC where 2x the memory is needed
to provide a circular map. This isn't needed in the zcb code in cpg
because it doesn't use a circular buffer.
Reviewed-by: Steven Dake <sdake@xxxxxxxxxx>
Signed-off-by: Jan Friesse <jfriesse@xxxxxxxxxx>
---
exec/cpg.c | 17 ++++-------------
lib/cpg.c | 18 +++++-------------
2 files changed, 9 insertions(+), 26 deletions(-)
diff --git a/exec/cpg.c b/exec/cpg.c
index 695f311..bc5feb6 100644
--- a/exec/cpg.c
+++ b/exec/cpg.c
@@ -1603,7 +1603,6 @@ memory_map (
void **buf)
{
int32_t fd;
- void *addr_orig;
void *addr;
int32_t res;
@@ -1620,18 +1619,10 @@ memory_map (
goto error_close_unlink;
}
- addr_orig = mmap (NULL, bytes, PROT_NONE,
- MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ addr = mmap (NULL, bytes, PROT_READ | PROT_WRITE,
+ MAP_SHARED, fd, 0);
- if (addr_orig == MAP_FAILED) {
- goto error_close_unlink;
- }
-
- addr = mmap (addr_orig, bytes, PROT_READ | PROT_WRITE,
- MAP_FIXED | MAP_SHARED, fd, 0);
-
- if (addr != addr_orig) {
- munmap(addr_orig, bytes);
+ if (addr == MAP_FAILED) {
goto error_close_unlink;
}
#ifdef MADV_NOSYNC
@@ -1642,7 +1633,7 @@ memory_map (
if (res) {
return (-1);
}
- *buf = addr_orig;
+ *buf = addr;
return (0);
error_close_unlink:
diff --git a/lib/cpg.c b/lib/cpg.c
index b96df4e..8408466 100644
--- a/lib/cpg.c
+++ b/lib/cpg.c
@@ -730,7 +730,6 @@ static int
memory_map (char *path, const char *file, void **buf, size_t bytes)
{
int32_t fd;
- void *addr_orig;
void *addr;
int32_t res;
char *buffer;
@@ -772,28 +771,21 @@ retry_write:
}
free (buffer);
- addr_orig = mmap (NULL, bytes, PROT_NONE,
- MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ addr = mmap (NULL, bytes, PROT_READ | PROT_WRITE,
+ MAP_SHARED, fd, 0);
- if (addr_orig == MAP_FAILED) {
- goto error_close_unlink;
- }
-
- addr = mmap (addr_orig, bytes, PROT_READ | PROT_WRITE,
- MAP_FIXED | MAP_SHARED, fd, 0);
-
- if (addr != addr_orig) {
+ if (addr == MAP_FAILED) {
goto error_close_unlink;
}
#ifdef MADV_NOSYNC
- madvise(addr_orig, bytes, MADV_NOSYNC);
+ madvise(addr, bytes, MADV_NOSYNC);
#endif
res = close (fd);
if (res) {
return (-1);
}
- *buf = addr_orig;
+ *buf = addr;
return 0;
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