I noticed for some time now a relatively high CPU usage of the user level ppp even on slow links. On my ADSL line (768/128) ppp consumes up to 20% CPU time (AMD K6-2 300MHz).
I trussed the process and noticed, that it calls getprotobynumber() for each packet it receives. In most cases, the result from this call isn't used at all - only with debugging enabled or on errors. getprotobynumber() scans /etc/protocols - or even more expensive functions if NSS is involved.
Below is a patch which reduces the getprotobynumber() calls, so they only get called if there is log output at all.
With this patch, the CPU usage dropped from 20% to under 3% (on my full blown ADSL link)
Daniel
Index: usr.sbin/ppp/ip.c
===================================================================
RCS file: /export/cvs/src/usr.sbin/ppp/ip.c,v
retrieving revision 1.100
diff -u -r1.100 ip.c
--- usr.sbin/ppp/ip.c 26 Mar 2003 02:27:32 -0000 1.100
+++ usr.sbin/ppp/ip.c 11 Dec 2003 22:20:27 -0000
@@ -161,6 +161,18 @@
}
}
+char *toprototxt(int cproto)
+{
+ static char prototxt[16];
+ struct protoent *pe;
+
+ if ((pe = getprotobynumber(cproto)) == NULL)
+ snprintf(prototxt, sizeof prototxt, "%d", cproto);
+ else
+ snprintf(prototxt, sizeof prototxt, "%s", pe->p_name);
+ return prototxt;
+}
+
/*
* Check a packet against the given filter
* Returns 0 to accept the packet, non-zero to drop the packet.
@@ -187,8 +199,7 @@
int match; /* true if condition matched */
int mindata; /* minimum data size or zero */
const struct filterent *fp = filter->rule;
- char dbuff[100], dstip[16], prototxt[16];
- struct protoent *pe;
+ char dbuff[100], dstip[16];
struct ncpaddr srcaddr, dstaddr;
const char *payload; /* IP payload */
int datalen; /* IP datagram length */
@@ -239,10 +250,6 @@
cproto = pip->ip_p;
}
- if ((pe = getprotobynumber(cproto)) == NULL)
- snprintf(prototxt, sizeof prototxt, "%d", cproto);
- else
- snprintf(prototxt, sizeof prototxt, "%s", pe->p_name);
gotinfo = estab = syn = finrst = didname = 0;
sport = dport = 0;
@@ -356,7 +363,7 @@
if (datalen < mindata) {
log_Printf(LogFILTER, " error: proto %s must be at least"
- " %d octets\n", prototxt, mindata);
+ " %d octets\n", toprototxt(cproto), mindata);
return 1;
}
@@ -367,7 +374,8 @@
", estab = %d, syn = %d, finrst = %d",
estab, syn, finrst);
}
- log_Printf(LogDEBUG, " Filter: proto = %s, %s\n", prototxt, dbuff);
+ log_Printf(LogDEBUG, " Filter: proto = %s, %s\n",
+ toprototxt(cproto), dbuff);
}
gotinfo = 1;
}
@@ -424,7 +432,8 @@
if (log_IsKept(LogFILTER)) {
snprintf(dstip, sizeof dstip, "%s", ncpaddr_ntoa(&dstaddr));
log_Printf(LogFILTER, "%sbound rule = %d accept %s "
- "src = %s:%d dst = %s:%d\n", filter->name, n, prototxt,
+ "src = %s:%d dst = %s:%d\n", filter->name, n,
+ toprototxt(cproto),
ncpaddr_ntoa(&srcaddr), sport, dstip, dport);
}
}
@@ -434,7 +443,7 @@
snprintf(dstip, sizeof dstip, "%s", ncpaddr_ntoa(&dstaddr));
log_Printf(LogFILTER,
"%sbound rule = %d deny %s src = %s/%d dst = %s/%d\n",
- filter->name, n, prototxt,
+ filter->name, n, toprototxt(cproto),
ncpaddr_ntoa(&srcaddr), sport, dstip, dport);
}
return 1;
@@ -450,7 +459,7 @@
snprintf(dstip, sizeof dstip, "%s", ncpaddr_ntoa(&dstaddr));
log_Printf(LogFILTER,
"%sbound rule = implicit deny %s src = %s/%d dst = %s/%d\n",
- filter->name, prototxt, ncpaddr_ntoa(&srcaddr), sport,
+ filter->name, toprototxt(cproto), ncpaddr_ntoa(&srcaddr), sport,
dstip, dport);
}
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