Date: Mon, 28 Apr 2008 17:17:26 -0700 From: Julian Elischer <julian@elischer.org> To: FreeBSD Net <freebsd-net@freebsd.org> Subject: mbuf usage in packets.. Message-ID: <48166916.8090801@elischer.org>
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I wrote a cruddy little profiler to profile the packets being sent
on my system..
after a bit of a live session including things like "ls -lR /usr"
I dumped out the results:
root@trafmon2:sysctl -b kern.ipc.mbufprofile
wasted:
0 0 0 0 0 736 13092 66773 54226 0 23 2322 21696 0 0 0
used:
0 0 0 0 0 4 2355 43755 88719 23309 438 288 0 0 0 0
segments:
0 82974 75819 23 10 10 9 7 5 2 6 2 1 0 0 0
================
Interpretation:
for how many mbufs per packet:
no packets had 0 segments (duh) but almost as many had 2 as had 1
0 - 0
1 - 82974
2 - 75819
3 - 23
4 - 10
5 - 10
6 - 9
7 - 7
8 - 5
9 - 2
10 - 6
11 - 2
12 - 1 One packet had 12 mbufs?!
13 - 0
14 - 0
15 - 0
for total packet data size:
0 hd 0
0 had 1
0 had 2,3
0 had 4-7
0 had 8-15
4 had 16-31
2355 had 32-63
43755 had 64-127
88719 had 128-255
23309 had 256-511
438 had 512-1023
288 had 1024-2047
for wasted space:
736 had between 16-31 unused bytes
13092 had 32-63 unused bytes
66773 had 64-127 unused bytes
54226 had 128-255 unused bytes
0 had 256-511 unused bytes (!)
23 had 512-1023 unused bytes
2322 had 1024-2047 unused bytes
21696 had 2048-4096 unused bytes (!)
profiling diff attached..
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Content-Type: text/plain; x-mac-type="0"; x-mac-creator="0";
name="mbprofile.diff"
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filename="mbprofile.diff"
Index: conf/options
===================================================================
RCS file: /usr/local/cvsroot/freebsd/src/sys/conf/options,v
retrieving revision 1.626
diff -d -u -r1.626 options
--- conf/options 20 Apr 2008 20:35:35 -0000 1.626
+++ conf/options 29 Apr 2008 00:04:47 -0000
@@ -388,6 +388,7 @@
LIBMCHAIN
LIBALIAS
MBUF_STRESS_TEST
+MBUF_PROFILING
NCP
NETATALK opt_atalk.h
PPP_BSDCOMP opt_ppp.h
Index: kern/uipc_mbuf.c
===================================================================
RCS file: /usr/local/cvsroot/freebsd/src/sys/kern/uipc_mbuf.c,v
retrieving revision 1.177
diff -d -u -r1.177 uipc_mbuf.c
--- kern/uipc_mbuf.c 25 Mar 2008 09:38:59 -0000 1.177
+++ kern/uipc_mbuf.c 29 Apr 2008 00:04:53 -0000
@@ -35,6 +35,7 @@
#include "opt_mac.h"
#include "opt_param.h"
#include "opt_mbuf_stress_test.h"
+#include "opt_mbuf_profiling.h"
#include <sys/param.h>
#include <sys/systm.h>
@@ -1938,3 +1939,118 @@
}
return (m0);
}
+
+#ifdef MBUF_PROFILING
+
+#define MP_BUCKETS 32 /* don't just change this things may overflow.*/
+struct mbufprofile {
+ u_int64_t wasted[MP_BUCKETS];
+ u_int64_t used[MP_BUCKETS];
+ u_int64_t segments[MP_BUCKETS];
+} mbprof;
+
+#define MP_MAXDIGITS 21 /* strlen("16,000,000,000,000,000,000") == 21 */
+#define MP_NUMLINES 6
+#define MP_NUMSPERLINE 16
+#define MP_EXTRABYTES 64 /* > strlen("used:\nwasted:\nsegments:\n") */
+/* work out max space needed and add a bit of spare space too */
+#define MP_MAXLINE ((MP_MAXDIGITS+1) * MP_NUMSPERLINE)
+#define MP_BUFSIZE ((MP_MAXLINE * MP_NUMLINES) + 1 + MP_EXTRABYTES)
+
+char mbprofbuf[MP_BUFSIZE];
+
+void
+m_profile(struct mbuf *m)
+{
+ int segments = 0;
+ int used = 0;
+ int wasted = 0;
+
+ while (m) {
+ segments++;
+ used += m->m_len;
+ if (m->m_flags & M_EXT) {
+ wasted += MHLEN - sizeof(m->m_ext) +
+ m->m_ext.ext_size - m->m_len;
+ } else {
+ if (m->m_flags & M_PKTHDR)
+ wasted += MHLEN - m->m_len;
+ else
+ wasted += MLEN - m->m_len;
+ }
+ m = m->m_next;
+ }
+ /* be paranoid.. it helps */
+ if (segments > MP_BUCKETS - 1)
+ segments = MP_BUCKETS - 1;
+ if (used > 10000000)
+ used = 10000000;
+ if (wasted > 10000000)
+ wasted = 10000000;
+ /* store in the appropriate bucket */
+ /* don't bother locking. if it's slightly off, so what? */
+ mbprof.segments[segments]++;
+ mbprof.used[fls(used)]++;
+ mbprof.wasted[fls(wasted)]++;
+}
+
+static void
+mbprof_textify(void)
+{
+ int offset;
+ char *c;
+ u_int64_t *p;
+
+
+ p = &mbprof.wasted[0];
+ c = mbprofbuf;
+ offset = snprintf(c, MP_MAXLINE + 10,
+ "wasted:\n%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld\n",
+ p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
+ p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
+ p = &mbprof.wasted[16];
+ c += offset;
+ offset = snprintf(c, MP_MAXLINE,
+ "%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld\n",
+ p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
+ p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
+ p = &mbprof.used[0];
+ c += offset;
+ offset = snprintf(c, MP_MAXLINE + 10,
+ "used:\n%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld\n",
+ p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
+ p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
+ p = &mbprof.used[16];
+ c += offset;
+ offset = snprintf(c, MP_MAXLINE,
+ "%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld\n",
+ p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
+ p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
+ p = &mbprof.segments[0];
+ c += offset;
+ offset = snprintf(c, MP_MAXLINE + 10,
+ "segments:\n%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld\n",
+ p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
+ p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
+ p = &mbprof.segments[16];
+ c += offset;
+ offset = snprintf(c, MP_MAXLINE,
+ "%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld\n",
+ p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],
+ p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
+}
+
+static int
+mbprof_handler(SYSCTL_HANDLER_ARGS)
+{
+ int error;
+
+ mbprof_textify();
+ error = SYSCTL_OUT(req, mbprofbuf, strlen(mbprofbuf) + 1);
+ return (error);
+}
+
+SYSCTL_PROC(_kern_ipc, OID_AUTO, mbufprofile, CTLTYPE_STRING|CTLFLAG_RD,
+ NULL, 0, mbprof_handler, "S", "mbuf profiling statistics");
+#endif
+
Index: net/if_ethersubr.c
===================================================================
RCS file: /usr/local/cvsroot/freebsd/src/sys/net/if_ethersubr.c,v
retrieving revision 1.244
diff -d -u -r1.244 if_ethersubr.c
--- net/if_ethersubr.c 20 Mar 2008 06:19:34 -0000 1.244
+++ net/if_ethersubr.c 29 Apr 2008 00:04:56 -0000
@@ -37,6 +37,7 @@
#include "opt_mac.h"
#include "opt_netgraph.h"
#include "opt_carp.h"
+#include "opt_mbuf_profiling.h"
#include <sys/param.h>
#include <sys/systm.h>
@@ -162,6 +163,7 @@
senderr(error);
#endif
+ M_PROFILE(m);
if (ifp->if_flags & IFF_MONITOR)
senderr(ENETDOWN);
if (!((ifp->if_flags & IFF_UP) &&
Index: sys/mbuf.h
===================================================================
RCS file: /usr/local/cvsroot/freebsd/src/sys/sys/mbuf.h,v
retrieving revision 1.224
diff -d -u -r1.224 mbuf.h
--- sys/mbuf.h 25 Mar 2008 09:39:02 -0000 1.224
+++ sys/mbuf.h 29 Apr 2008 00:04:57 -0000
@@ -959,4 +959,12 @@
#endif /* _KERNEL */
+#ifdef MBUF_PROFILING
+ void m_profile(struct mbuf *m);
+ #define M_PROFILE(m) m_profile(m)
+#else
+ #define M_PROFILE(m)
+#endif
+
+
#endif /* !_SYS_MBUF_H_ */
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