On Sat, 6 Apr 2024 at 23:17, Jelte Fennema-Nio <postg...@jeltef.nl> wrote:
> Weird that on your machines you don't see a difference. Are you sure
> you didn't make a silly mistake, like not restarting postgres or
> something?
I'm sure. I spent quite a long time between the AMD and an Apple m2 trying.
I did see the same regression as you on the smaller numbers. I
experimented with the attached which macro'ifies internal_flush() and
pg_noinlines internal_flush_buffer.
Can you try that to see if it gets rid of the regression on the first two tests?
David
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index 6497100a1a..824b2f11a3 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -120,8 +120,8 @@ static List *sock_paths = NIL;
static char *PqSendBuffer;
static int PqSendBufferSize; /* Size send buffer */
-static int PqSendPointer; /* Next index to store a byte in
PqSendBuffer */
-static int PqSendStart; /* Next index to send a byte in
PqSendBuffer */
+static size_t PqSendPointer; /* Next index to store a byte in
PqSendBuffer */
+static size_t PqSendStart; /* Next index to send a byte in
PqSendBuffer */
static char PqRecvBuffer[PQ_RECV_BUFFER_SIZE];
static int PqRecvPointer; /* Next index to read a byte from
PqRecvBuffer */
@@ -133,6 +133,7 @@ static int PqRecvLength; /* End of data
available in PqRecvBuffer */
static bool PqCommBusy; /* busy sending data to the
client */
static bool PqCommReadingMsg; /* in the middle of reading a message */
+#define internal_flush() internal_flush_buffer(PqSendBuffer,
&PqSendStart, &PqSendPointer)
/* Internal functions */
static void socket_comm_reset(void);
@@ -144,7 +145,8 @@ static bool socket_is_send_pending(void);
static int socket_putmessage(char msgtype, const char *s, size_t len);
static void socket_putmessage_noblock(char msgtype, const char *s, size_t len);
static int internal_putbytes(const char *s, size_t len);
-static int internal_flush(void);
+static pg_noinline int internal_flush_buffer(const char *s, size_t *start,
+
size_t *end);
static int Lock_AF_UNIX(const char *unixSocketDir, const char
*unixSocketPath);
static int Setup_AF_UNIX(const char *sock_path);
@@ -1282,14 +1284,32 @@ internal_putbytes(const char *s, size_t len)
if (internal_flush())
return EOF;
}
- amount = PqSendBufferSize - PqSendPointer;
- if (amount > len)
- amount = len;
- memcpy(PqSendBuffer + PqSendPointer, s, amount);
- PqSendPointer += amount;
- s += amount;
- len -= amount;
+
+ /*
+ * If the buffer is empty and data length is larger than the
buffer
+ * size, send it without buffering. Otherwise, put as much data
as
+ * possible into the buffer.
+ */
+ if (len >= PqSendBufferSize && PqSendStart == PqSendPointer)
+ {
+ size_t start = 0;
+
+ socket_set_nonblocking(false);
+ if (internal_flush_buffer(s, &start, &len))
+ return EOF;
+ }
+ else
+ {
+ amount = PqSendBufferSize - PqSendPointer;
+ if (amount > len)
+ amount = len;
+ memcpy(PqSendBuffer + PqSendPointer, s, amount);
+ PqSendPointer += amount;
+ s += amount;
+ len -= amount;
+ }
}
+
return 0;
}
@@ -1315,19 +1335,19 @@ socket_flush(void)
}
/* --------------------------------
- * internal_flush - flush pending output
+ * internal_flush_buffer - flush the given buffer content
*
* Returns 0 if OK (meaning everything was sent, or operation would block
* and the socket is in non-blocking mode), or EOF if trouble.
* --------------------------------
*/
-static int
-internal_flush(void)
+static pg_noinline int
+internal_flush_buffer(const char *s, size_t *start, size_t *end)
{
static int last_reported_send_errno = 0;
- char *bufptr = PqSendBuffer + PqSendStart;
- char *bufend = PqSendBuffer + PqSendPointer;
+ char *bufptr = (char*) s + *start;
+ char *bufend = (char*) s + *end;
while (bufptr < bufend)
{
@@ -1373,7 +1393,7 @@ internal_flush(void)
* flag that'll cause the next CHECK_FOR_INTERRUPTS to
terminate
* the connection.
*/
- PqSendStart = PqSendPointer = 0;
+ *start = *end = 0;
ClientConnectionLost = 1;
InterruptPending = 1;
return EOF;
@@ -1381,10 +1401,10 @@ internal_flush(void)
last_reported_send_errno = 0; /* reset after any successful
send */
bufptr += r;
- PqSendStart += r;
+ *start += r;
}
- PqSendStart = PqSendPointer = 0;
+ *start = *end = 0;
return 0;
}
