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Reuse hash table bucket entries if they're stale 32+ seconds
author
Matt Corallo
<git@bluematt.me>
Tue, 14 Sep 2021 18:02:47 +0000
(18:02 +0000)
committer
Matt Corallo
<git@bluematt.me>
Tue, 14 Sep 2021 18:49:39 +0000
(18:49 +0000)
genrules.py
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xdp.c
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diff --git
a/genrules.py
b/genrules.py
index 93c22f5c9059dfb7f7cccefa7707dda1fb849871..3f901e1c908a1595e35264279016e01e37874c7c 100755
(executable)
--- a/
genrules.py
+++ b/
genrules.py
@@
-404,7
+404,7
@@
with open("rules.h", "w") as out:
value = 1.0 + mantissa / (2**23)
value *= 2**(exp-127)
value = 1.0 + mantissa / (2**23)
value *= 2**(exp-127)
- first_action = "int64_t time = bpf_ktime_get_ns() & RATE_TIME_MASK;\n"
+ first_action = "int64_t time
_masked
= bpf_ktime_get_ns() & RATE_TIME_MASK;\n"
first_action += f"int64_t per_pkt_ns = (1000000000LL << RATE_BUCKET_INTEGER_BITS) / {math.floor(value)};\n"
if ty == "0x8006" or ty == "0x800c":
spin_lock = "bpf_spin_lock(&rate->lock);"
first_action += f"int64_t per_pkt_ns = (1000000000LL << RATE_BUCKET_INTEGER_BITS) / {math.floor(value)};\n"
if ty == "0x8006" or ty == "0x800c":
spin_lock = "bpf_spin_lock(&rate->lock);"
@@
-420,13
+420,13
@@
with open("rules.h", "w") as out:
continue
first_action += f"const uint32_t srcip = ip->saddr & MASK4({mid_byte});\n"
first_action += f"void *rate_map = &v4_src_rate_{len(v4persrcratelimits)};\n"
continue
first_action += f"const uint32_t srcip = ip->saddr & MASK4({mid_byte});\n"
first_action += f"void *rate_map = &v4_src_rate_{len(v4persrcratelimits)};\n"
- first_action += f"struct persrc_rate4_ptr rate_ptr = get_v4_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096});\n"
+ first_action += f"struct persrc_rate4_ptr rate_ptr = get_v4_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}
, time_masked
);\n"
first_action += f"struct persrc_rate4_entry *rate = rate_ptr.rate;\n"
v4persrcratelimits.append((high_byte + 1) * 4096)
elif mid_byte <= 64:
first_action += f"const uint64_t srcip = BE128BEHIGH64(ip6->saddr & MASK6({mid_byte}));\n"
first_action += f"void *rate_map = &v5_src_rate_{len(v5persrcratelimits)};\n"
first_action += f"struct persrc_rate4_entry *rate = rate_ptr.rate;\n"
v4persrcratelimits.append((high_byte + 1) * 4096)
elif mid_byte <= 64:
first_action += f"const uint64_t srcip = BE128BEHIGH64(ip6->saddr & MASK6({mid_byte}));\n"
first_action += f"void *rate_map = &v5_src_rate_{len(v5persrcratelimits)};\n"
- first_action += f"struct persrc_rate5_ptr rate_ptr = get_v5_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096});\n"
+ first_action += f"struct persrc_rate5_ptr rate_ptr = get_v5_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}
, time_masked
);\n"
first_action += f"struct persrc_rate5_entry *rate = rate_ptr.rate;\n"
v5persrcratelimits.append((high_byte + 1) * 4096)
else:
first_action += f"struct persrc_rate5_entry *rate = rate_ptr.rate;\n"
v5persrcratelimits.append((high_byte + 1) * 4096)
else:
@@
-434,7
+434,7
@@
with open("rules.h", "w") as out:
continue
first_action += f"const uint128_t srcip = ip6->saddr & MASK6({mid_byte});\n"
first_action += f"void *rate_map = &v6_src_rate_{len(v6persrcratelimits)};\n"
continue
first_action += f"const uint128_t srcip = ip6->saddr & MASK6({mid_byte});\n"
first_action += f"void *rate_map = &v6_src_rate_{len(v6persrcratelimits)};\n"
- first_action += f"struct persrc_rate6_ptr rate_ptr = get_v6_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096});\n"
+ first_action += f"struct persrc_rate6_ptr rate_ptr = get_v6_persrc_ratelimit(srcip, rate_map, {(high_byte + 1) * 4096}
, time_masked
);\n"
first_action += f"struct persrc_rate6_entry *rate = rate_ptr.rate;\n"
v6persrcratelimits.append((high_byte + 1) * 4096)
if ty == "0x8006" or ty == "0x8306":
first_action += f"struct persrc_rate6_entry *rate = rate_ptr.rate;\n"
v6persrcratelimits.append((high_byte + 1) * 4096)
if ty == "0x8006" or ty == "0x8306":
@@
-445,7
+445,7
@@
with open("rules.h", "w") as out:
first_action += f"\t{spin_lock}\n"
first_action += "\tint64_t bucket_pkts = (rate->sent_time & (~RATE_TIME_MASK)) >> (64 - RATE_BUCKET_BITS);\n"
# We mask the top 12 bits, so date overflows every 52 days, handled below
first_action += f"\t{spin_lock}\n"
first_action += "\tint64_t bucket_pkts = (rate->sent_time & (~RATE_TIME_MASK)) >> (64 - RATE_BUCKET_BITS);\n"
# We mask the top 12 bits, so date overflows every 52 days, handled below
- first_action += "\tint64_t time_diff = time - ((int64_t)(rate->sent_time & RATE_TIME_MASK));\n"
+ first_action += "\tint64_t time_diff = time
_masked
- ((int64_t)(rate->sent_time & RATE_TIME_MASK));\n"
first_action += "\tif (unlikely(time_diff < -1000000000 || time_diff > 16000000000)) {\n"
first_action += "\t\tbucket_pkts = 0;\n"
first_action += "\t} else {\n"
first_action += "\tif (unlikely(time_diff < -1000000000 || time_diff > 16000000000)) {\n"
first_action += "\t\tbucket_pkts = 0;\n"
first_action += "\t} else {\n"
@@
-459,7
+459,7
@@
with open("rules.h", "w") as out:
first_action += "\t\treturn XDP_DROP;\n"
first_action += "\t} else {\n"
first_action += "\t\tif (unlikely(bucket_pkts < 0)) bucket_pkts = 0;\n"
first_action += "\t\treturn XDP_DROP;\n"
first_action += "\t} else {\n"
first_action += "\t\tif (unlikely(bucket_pkts < 0)) bucket_pkts = 0;\n"
- first_action += f"\t\trate->sent_time = time | ((bucket_pkts + (1 << RATE_BUCKET_DECIMAL_BITS)) << (64 - RATE_BUCKET_BITS));\n"
+ first_action += f"\t\trate->sent_time = time
_masked
| ((bucket_pkts + (1 << RATE_BUCKET_DECIMAL_BITS)) << (64 - RATE_BUCKET_BITS));\n"
first_action += f"\t\t{spin_unlock}\n"
first_action += "\t}\n"
first_action += "}\n"
first_action += f"\t\t{spin_unlock}\n"
first_action += "\t}\n"
first_action += "}\n"
diff --git
a/xdp.c
b/xdp.c
index 6a8c19e4f852bad1e108093332043d0033f8e55b..ad6ab82db97feedc53f88f9f9f3f067d65bcbb7f 100644
(file)
--- a/
xdp.c
+++ b/
xdp.c
@@
-185,6
+185,11
@@
struct {
#define RATE_BUCKET_BITS (RATE_BUCKET_DECIMAL_BITS + RATE_BUCKET_INTEGER_BITS)
#define RATE_TIME_MASK ((1ULL << (64 - RATE_BUCKET_BITS)) - 1)
#define RATE_BUCKET_BITS (RATE_BUCKET_DECIMAL_BITS + RATE_BUCKET_INTEGER_BITS)
#define RATE_TIME_MASK ((1ULL << (64 - RATE_BUCKET_BITS)) - 1)
+// Time going backwards 10ms+ or forward 32sec+ implies we should consider it
+// an overflow, or at least stale enough that we should reset the entry.
+#define RATE_MIN_TIME_OFFSET -10000000LL
+#define RATE_MAX_TIME_OFFSET 32000000000LL
+
#ifdef RATE_CNT
struct ratelimit {
struct bpf_spin_lock lock;
#ifdef RATE_CNT
struct ratelimit {
struct bpf_spin_lock lock;
@@
-232,7
+237,7
@@
struct persrc_rate##IPV##_ptr { \
}; \
\
__attribute__((always_inline)) \
}; \
\
__attribute__((always_inline)) \
-static inline struct persrc_rate##IPV##_ptr get_v##IPV##_persrc_ratelimit(IP_TYPE key, void *map, size_t map_limit) { \
+static inline struct persrc_rate##IPV##_ptr get_v##IPV##_persrc_ratelimit(IP_TYPE key, void *map, size_t map_limit
, int64_t cur_time_masked
) { \
struct persrc_rate##IPV##_ptr res = { .rate = NULL, .lock = NULL }; \
uint64_t hash = siphash(&key, sizeof(key), COMPILE_TIME_RAND); \
\
struct persrc_rate##IPV##_ptr res = { .rate = NULL, .lock = NULL }; \
uint64_t hash = siphash(&key, sizeof(key), COMPILE_TIME_RAND); \
\
@@
-253,7
+258,13
@@
static inline struct persrc_rate##IPV##_ptr get_v##IPV##_persrc_ratelimit(IP_TYP
res.rate = &first_bucket[i]; \
res.lock = &buckets->lock; \
return res; \
res.rate = &first_bucket[i]; \
res.lock = &buckets->lock; \
return res; \
- } else if (min_sent_time > (first_bucket[i].sent_time & RATE_TIME_MASK)) { \
+ } \
+ int64_t time_offset = ((int64_t)cur_time_masked) - (first_bucket[i].sent_time & RATE_TIME_MASK); \
+ if (time_offset < RATE_MIN_TIME_OFFSET || time_offset > RATE_MAX_TIME_OFFSET) { \
+ min_sent_idx = i; \
+ break; \
+ } \
+ if ((first_bucket[i].sent_time & RATE_TIME_MASK) < min_sent_time) { \
min_sent_time = first_bucket[i].sent_time & RATE_TIME_MASK; \
min_sent_idx = i; \
} \
min_sent_time = first_bucket[i].sent_time & RATE_TIME_MASK; \
min_sent_idx = i; \
} \