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Open files with O_DIRECT dependent on a compile-time DIRECT_IO #define.

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O_DIRECT causes problems on (at least) a wheezy VM, and there are mixed
reports about its performance impact.  This patch makes it a
compile-time choice which should remain until it's been benchmarked.
This commit is contained in:
Alex Young
2012-07-14 10:07:58 +01:00
parent 03c06a689d
commit c6e6952def
3 changed files with 17 additions and 5 deletions
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12
src/ioutil.c
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@@ -83,13 +83,22 @@ int open_and_mmap(const char* filename, int* out_fd, off64_t *out_size, void **o
{
off64_t size;
*out_fd = open(filename, O_RDWR|O_DIRECT|O_SYNC);
/* O_DIRECT seems to be intermittently supported. Leaving it as
* a compile-time option for now. */
#ifdef DIRECT_IO
*out_fd = open(filename, O_RDWR | O_DIRECT | O_SYNC );
#else
*out_fd = open(filename, O_RDWR | O_SYNC );
#endif
if (*out_fd < 1) {
warn("open(%s) failed: does it exist?", filename);
return *out_fd;
}
size = lseek64(*out_fd, 0, SEEK_END);
if (size < 0) {
warn("lseek64() failed");
return size;
}
if (out_size) {
@@ -100,6 +109,7 @@ int open_and_mmap(const char* filename, int* out_fd, off64_t *out_size, void **o
*out_map = mmap64(NULL, size, PROT_READ|PROT_WRITE, MAP_SHARED,
*out_fd, 0);
if (((long) *out_map) == -1) {
warn("mmap64() failed");
return -1;
}
}