Hi Honza,
Do you have plan to backport this patch to flatiron? I found that flatrion have the same dual mmap operation in its ipc code.
B.R.,
Jason
On 2013-5-20, at 21:57, Jan Friesse <jfriesse@xxxxxxxxxx> 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.
>
> Signed-off-by: Jan Friesse <jfriesse@xxxxxxxxxx>
> ---
> exec/cpg.c | 18 +++---------------
> lib/cpg.c | 19 ++++---------------
> 2 files changed, 7 insertions(+), 30 deletions(-)
>
> diff --git a/exec/cpg.c b/exec/cpg.c
> index 695f311..bfc3813 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;
>
> @@ -1620,20 +1619,9 @@ 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);
> - goto error_close_unlink;
> - }
> #ifdef MADV_NOSYNC
> madvise(addr, bytes, MADV_NOSYNC);
> #endif
> @@ -1642,7 +1630,7 @@ 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..f0ac593 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 +771,18 @@ 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) {
> - 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;
>
> --
> 1.7.1
>
> _______________________________________________
> discuss mailing list
> discuss@xxxxxxxxxxxx
> http://lists.corosync.org/mailman/listinfo/discuss
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