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Use select() to find out if any node has sent us data; more efficient

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than doing a read on each socket.
This commit is contained in:
Jim 2011-08-16 17:55:55 -04:00
parent 51dfd5101b
commit 8aac162418
1 changed files with 34 additions and 15 deletions
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49
devpnc.h
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@ -670,28 +670,48 @@ unsigned short pncxmit(t_dma *iob) {
return xstat;
}
/* do socket reads on all connections until 1 connection has a
complete packet, then return that packet to the Prime */
/* do socket reads on all active connections with data available until
1 connection has a complete packet, then return that packet to the
Prime */
pncrecv(time_t timenow) {
static int prevnode=MAXNODEID;
int i, nodeid;
static struct timeval timeout = {0, 0};
int nodeid, n, fd;
fd_set fds;
/* if connected with id 0, don't do reads */
if (myid == 0)
return;
i = prevnode;
/* do a select on all active nodes to see if there's any data available */
FD_ZERO(&fds);
for (nodeid=0; nodeid<=MAXNODEID; nodeid++)
if (ni[nodeid].cstate == PNCCSAUTH)
FD_SET(ni[nodeid].fd, &fds);
n = select(nodeid, &fds, NULL, NULL, &timeout);
if (n == -1) {
perror("unable to do read select on PNC fds");
fatal(NULL);
}
if (n == 0) {
TRACE(T_RIO, " pncrecv: no data\n");
return 0;
}
nodeid = prevnode;
while (1) {
i = (i % MAXNODEID) + 1;
if (i == myid) /* don't read from myself */
continue;
if (ni[i].cstate == PNCCSAUTH) {
if (pncrecv1(i))
nodeid = (nodeid % MAXNODEID) + 1;
fd = ni[nodeid].fd;
if (fd >= 0 && FD_ISSET(fd, &fds))
if (pncrecv1(nodeid))
break;
}
if (i == prevnode) /* went round once? */
if (nodeid == prevnode) /* went round once? */
break;
}
prevnode = i;
prevnode = nodeid;
}
/* try to read a complete packet from a node. On entry, the receive
@ -704,7 +724,7 @@ pncrecv(time_t timenow) {
pncrecv1(int nodeid) {
int pktlen, nw;
TRACE(T_RIO, " pncrecv1: reading from node %d\n", nodeid);
TRACE(T_RIO, " pncrecv1: read node %d\n", nodeid);
if (ni[nodeid].rcvlen < 2) {
if (!pncread(nodeid, 2 - ni[nodeid].rcvlen))
return 0;
@ -726,7 +746,7 @@ pncrecv1(int nodeid) {
/* send completed packet to the Prime */
TRACE(T_RIO, " pncrecv1: pkt complete\n");
TRACE(T_RIO, " pncrecv1: store pkt\n");
pncdumppkt(ni[nodeid].rcvpkt, ni[nodeid].rcvlen);
nw = (pktlen-4)/2;
if (nw > rcv.dmanw) {
@ -736,7 +756,6 @@ pncrecv1(int nodeid) {
}
/* modify to/from word to allow me to be in multiple rings */
*(unsigned short *)(ni[nodeid].rcvpkt+2) = (myid<<8) | nodeid;
memcpy(rcv.memp, ni[nodeid].rcvpkt+2, nw*2);