@@ -39,10 +39,34 @@ size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
* such "large" value is -1 (sinice size_t is unsigned),
* so specifying `-1' as `bytes' means 'up to the end of iovec'.
*/
-size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
- size_t offset, const void *buf, size_t bytes);
-size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
- size_t offset, void *buf, size_t bytes);
+size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
+ size_t offset, const void *buf, size_t bytes);
+size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
+ size_t offset, void *buf, size_t bytes);
+
+static inline size_t
+iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
+ size_t offset, const void *buf, size_t bytes)
+{
+ if (__builtin_constant_p(bytes) && iov_cnt && offset + bytes <= iov[0].iov_len) {
+ memcpy(iov[0].iov_base + offset, buf, bytes);
+ return bytes;
+ } else {
+ return iov_from_buf_full(iov, iov_cnt, offset, buf, bytes);
+ }
+}
+
+static inline size_t
+iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
+ size_t offset, void *buf, size_t bytes)
+{
+ if (__builtin_constant_p(bytes) && iov_cnt && offset + bytes <= iov[0].iov_len) {
+ memcpy(buf, iov[0].iov_base + offset, bytes);
+ return bytes;
+ } else {
+ return iov_to_buf_full(iov, iov_cnt, offset, buf, bytes);
+ }
+}
/**
* Set data bytes pointed out by iovec `iov' of size `iov_cnt' elements,
@@ -19,8 +19,8 @@
#include "qemu/iov.h"
#include "qemu/sockets.h"
-size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
- size_t offset, const void *buf, size_t bytes)
+size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
+ size_t offset, const void *buf, size_t bytes)
{
size_t done;
unsigned int i;
@@ -38,8 +38,8 @@ size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
return done;
}
-size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
- size_t offset, void *buf, size_t bytes)
+size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
+ size_t offset, void *buf, size_t bytes)
{
size_t done;
unsigned int i;
memcpy can take a large amount of time for small reads and writes. For virtio it is a common case that the first iovec can satisfy the whole read or write. In that case, and if bytes is a constant to avoid excessive growth of code, inline the first iteration into the caller. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- include/qemu/iov.h | 32 ++++++++++++++++++++++++++++---- util/iov.c | 8 ++++---- 2 files changed, 32 insertions(+), 8 deletions(-)