[bpf-next V4 PATCH 8/8] samples/bpf: xdp_monitor use err code from tracepoint xdp:xdp_devmap_xmit

Jesper Dangaard Brouer
2018-05-18T13:35:16Z

Update xdp_monitor to use the recently added err code introduced
in tracepoint xdp:xdp_devmap_xmit, to show if the drop count is
caused by some driver general delivery problem. Other kind of drops
will likely just be more normal TX space issues.
---
samples/bpf/xdp_monitor_kern.c | 10 ++++++++++
samples/bpf/xdp_monitor_user.c | 35 ++++++++++++++++++++++++++++++-----
2 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/samples/bpf/xdp_monitor_kern.c b/samples/bpf/xdp_monitor_kern.c
index 2854aa0665ea..ad10fe700d7d 100644
--- a/samples/bpf/xdp_monitor_kern.c
+++ b/samples/bpf/xdp_monitor_kern.c
@@ -125,6 +125,7 @@ struct datarec {
u64 processed;
u64 dropped;
u64 info;
+ u64 err;
};
#define MAX_CPUS 64

@@ -228,6 +229,7 @@ struct devmap_xmit_ctx {
int sent; // offset:24; size:4; signed:1;
int from_ifindex; // offset:28; size:4; signed:1;
int to_ifindex; // offset:32; size:4; signed:1;
+ int err; // offset:36; size:4; signed:1;
};

SEC("tracepoint/xdp/xdp_devmap_xmit")
@@ -245,5 +247,13 @@ int trace_xdp_devmap_xmit(struct devmap_xmit_ctx *ctx)
/* Record bulk events, then userspace can calc average bulk size */
rec->info += 1;

+ /* Record error cases, where no frame were sent */
+ if (ctx->err)
+ rec->err++;
+
+ /* Catch API error of drv ndo_xdp_xmit sent more than count */
+ if (ctx->drops < 0)
+ rec->err++;
+
return 1;
}
diff --git a/samples/bpf/xdp_monitor_user.c b/samples/bpf/xdp_monitor_user.c
index 7e18a454924c..dd558cbb2309 100644
--- a/samples/bpf/xdp_monitor_user.c
+++ b/samples/bpf/xdp_monitor_user.c
@@ -117,6 +117,7 @@ struct datarec {
__u64 processed;
__u64 dropped;
__u64 info;
+ __u64 err;
};
#define MAX_CPUS 64

@@ -152,6 +153,7 @@ static bool map_collect_record(int fd, __u32 key, struct record *rec)
__u64 sum_processed = 0;
__u64 sum_dropped = 0;
__u64 sum_info = 0;
+ __u64 sum_err = 0;
int i;

if ((bpf_map_lookup_elem(fd, &key, values)) != 0) {
@@ -170,10 +172,13 @@ static bool map_collect_record(int fd, __u32 key, struct record *rec)
sum_dropped += values[i].dropped;
rec->cpu[i].info = values[i].info;
sum_info += values[i].info;
+ rec->cpu[i].err = values[i].err;
+ sum_err += values[i].err;
}
rec->total.processed = sum_processed;
rec->total.dropped = sum_dropped;
rec->total.info = sum_info;
+ rec->total.err = sum_err;
return true;
}

@@ -274,6 +279,18 @@ static double calc_info(struct datarec *r, struct datarec *p, double period)
return pps;
}

+static double calc_err(struct datarec *r, struct datarec *p, double period)
+{
+ __u64 packets = 0;
+ double pps = 0;
+
+ if (period > 0) {
+ packets = r->err - p->err;
+ pps = packets / period;
+ }
+ return pps;
+}
+
static void stats_print(struct stats_record *stats_rec,
struct stats_record *stats_prev,
bool err_only)
@@ -412,11 +429,12 @@ static void stats_print(struct stats_record *stats_rec,

/* devmap ndo_xdp_xmit stats */
{
- char *fmt1 = "%-15s %-7d %'-12.0f %'-12.0f %'-10.2f %s\n";
- char *fmt2 = "%-15s %-7s %'-12.0f %'-12.0f %'-10.2f %s\n";
+ char *fmt1 = "%-15s %-7d %'-12.0f %'-12.0f %'-10.2f %s %s\n";
+ char *fmt2 = "%-15s %-7s %'-12.0f %'-12.0f %'-10.2f %s %s\n";
struct record *rec, *prev;
- double drop, info;
+ double drop, info, err;
char *i_str = "";
+ char *err_str = "";

rec = &stats_rec->xdp_devmap_xmit;
prev = &stats_prev->xdp_devmap_xmit;
@@ -428,22 +446,29 @@ static void stats_print(struct stats_record *stats_rec,
pps = calc_pps(r, p, t);
drop = calc_drop(r, p, t);
info = calc_info(r, p, t);
+ err = calc_err(r, p, t);
if (info > 0) {
i_str = "bulk-average";
info = (pps+drop) / info; /* calc avg bulk */
}
+ if (err > 0)
+ err_str = "drv-err";
if (pps > 0 || drop > 0)
printf(fmt1, "devmap-xmit",
- i, pps, drop, info, i_str);
+ i, pps, drop, info, i_str, err_str);
}
pps = calc_pps(&rec->total, &prev->total, t);
drop = calc_drop(&rec->total, &prev->total, t);
info = calc_info(&rec->total, &prev->total, t);
+ err = calc_err(&rec->total, &prev->total, t);
if (info > 0) {
i_str = "bulk-average";
info = (pps+drop) / info; /* calc avg bulk */
}
- printf(fmt2, "devmap-xmit", "total", pps, drop, info, i_str);
+ if (err > 0)
+ err_str = "drv-err";
+ printf(fmt2, "devmap-xmit", "total", pps, drop,
+ info, i_str, err_str);
}

printf("\n");