OPTIM: http: improve parsing performance of long header lines

A performance test with 1kB cookies was capping at 194k req/s. After
implementing multi-byte skipping, the performance increased to 212k req/s,
or 9.2% faster. This patch implements this for architectures supporting
unaligned accesses (x86_64, x86, armv7a). Maybe other architectures can
benefit from this but they were not tested yet.

diff --git a/src/proto_http.c b/src/proto_http.c
index 07c53ee2551dd7368a5479bbb52ab1fe4fec5116..c9f38b1b12790f535e266576d4dd920fae4e3244 100644 (file)
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -1922,8 +1922,31 @@ void http_msg_analyzer(struct http_msg *msg, struct hdr_idx *idx)
                /* assumes msg->sol points to the first char, and msg->sov
                 * points to the first character of the value.
                 */
+
+               /* speedup: we'll skip packs of 4 or 8 bytes not containing bytes 0x0D
+                * and lower. In fact since most of the time is spent in the loop, we
+                * also remove the sign bit test so that bytes 0x8e..0x0d break the
+                * loop, but we don't care since they're very rare in header values.
+                */
+#if defined(__x86_64__)
+               while (ptr <= end - sizeof(long)) {
+                       if ((*(long *)ptr - 0x0e0e0e0e0e0e0e0eULL) & 0x8080808080808080ULL)
+                               goto http_msg_hdr_val2;
+                       ptr += sizeof(long);
+               }
+#endif
+#if defined(__x86_64__) || \
+    defined(__i386__) || defined(__i486__) || defined(__i586__) || defined(__i686__) || \
+    defined(__ARM_ARCH_7A__)
+               while (ptr <= end - sizeof(int)) {
+                       if ((*(int*)ptr - 0x0e0e0e0e) & 0x80808080)
+                               goto http_msg_hdr_val2;
+                       ptr += sizeof(int);
+               }
+#endif
+       http_msg_hdr_val2:
                if (likely(!HTTP_IS_CRLF(*ptr)))
-                       EAT_AND_JUMP_OR_RETURN(http_msg_hdr_val, HTTP_MSG_HDR_VAL);
+                       EAT_AND_JUMP_OR_RETURN(http_msg_hdr_val2, HTTP_MSG_HDR_VAL);
 
                msg->eol = ptr - buf->p;
                /* Note: we could also copy eol into ->eoh so that we have the