From df0131458705400d181f9b4d3ce4a0be8be0471a Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Tue, 25 May 2021 19:19:54 +0000 Subject: [PATCH] Drop union in rate limiting struct that is just confusing --- genrules.py | 18 +++++++----------- xdp.c | 10 ++-------- 2 files changed, 9 insertions(+), 19 deletions(-) diff --git a/genrules.py b/genrules.py index 5d90e8c..a8ad71a 100755 --- a/genrules.py +++ b/genrules.py @@ -402,10 +402,6 @@ with open("rules.h", "w") as out: mantissa = low_bytes & ((1 << 23) - 1) value = 1.0 + mantissa / (2**23) value *= 2**(exp-127) - if ty == "0x8006" or ty == "0x8306": - accessor = "rate->rate.sent_bytes" - else: - accessor = "rate->rate.sent_packets" # Note that int64_t will overflow after 292 years of uptime first_action = "int64_t time = bpf_ktime_get_ns();\n" first_action += "uint64_t allowed_since_last = 0;\n" @@ -433,19 +429,19 @@ with open("rules.h", "w") as out: first_action += f"struct percpu_ratelimit *rate = bpf_map_lookup_elem(rate_map, &srcip);\n" first_action += "if (rate) {\n" first_action += f"\t{spin_lock}\n" - first_action += f"\tif (likely({accessor} > 0))" + " {\n" + first_action += "\tif (likely(rate->sent_rate > 0))" + " {\n" first_action += "\t\tint64_t diff = time - rate->sent_time;\n" # Unlikely or not, if the flow is slow, take a perf hit (though with the else if branch it doesn't matter) first_action += "\t\tif (unlikely(diff > 1000000000))\n" - first_action += f"\t\t\t{accessor} = 0;\n" + first_action += "\t\t\trate->sent_rate = 0;\n" first_action += "\t\telse if (likely(diff > 0))\n" first_action += f"\t\t\tallowed_since_last = ((uint64_t)diff) * {math.floor(value)} / 1000000000;\n" first_action += "\t}\n" - first_action += f"\tif ({accessor} - ((int64_t)allowed_since_last) <= 0)" + " {\n" + first_action += "\tif (rate->sent_rate - ((int64_t)allowed_since_last) <= 0)" + " {\n" if ty == "0x8006" or ty == "0x8306": - first_action += f"\t\t{accessor} = data_end - pktdata;\n" + first_action += "\t\trate->sent_rate = data_end - pktdata;\n" else: - first_action += f"\t\t{accessor} = 1;\n" + first_action += "\t\trate->sent_rate = 1;\n" first_action += "\t\trate->sent_time = time;\n" first_action += f"\t\t{spin_unlock}\n" first_action += "\t} else {\n" @@ -458,9 +454,9 @@ with open("rules.h", "w") as out: first_action += "\tstruct percpu_ratelimit new_rate = { .sent_time = time, };\n" first_action += "\trate = &new_rate;\n" if ty == "0x8006" or ty == "0x8306": - first_action += f"\t\t{accessor} = data_end - pktdata;\n" + first_action += f"\t\trate->sent_rate = data_end - pktdata;\n" else: - first_action += f"\t\t{accessor} = 1;\n" + first_action += f"\t\trate->sent_rate = 1;\n" first_action += "\tbpf_map_update_elem(rate_map, &srcip, rate, BPF_ANY);\n" first_action += "}\n" elif ty == "0x8007": diff --git a/xdp.c b/xdp.c index 87544ba..de4d86e 100644 --- a/xdp.c +++ b/xdp.c @@ -175,10 +175,7 @@ struct { #ifdef RATE_CNT struct ratelimit { struct bpf_spin_lock lock; - union { - int64_t sent_bytes; - int64_t sent_packets; - } rate; + int64_t sent_rate; int64_t sent_time; }; struct { @@ -194,10 +191,7 @@ struct { // map_check_btf as of Linux 5.10). // This isn't exactly accurate, but at least its faster. struct percpu_ratelimit { - union { - int64_t sent_bytes; - int64_t sent_packets; - } rate; + int64_t sent_rate; int64_t sent_time; }; -- 2.39.5