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ntp: avoid unnecessary source lookups

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Avoid searching the hash table of sources when a packet in the client
mode is received. It cannot be a response from our source. Analogously,
avoid source lookups for transmitted packets in the server mode. This
doesn't change anything for packets in symmetric modes, which can be
requests and responses at the same time.

This slightly improves the maximum packet rate handled as a server.
This commit is contained in:
Miroslav Lichvar 2021-12-14 10:04:39 +01:00
parent fcd384523b
commit f2ba20f293
2 changed files with 14 additions and 7 deletions
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12
ntp_sources.c
View file

@ -1100,8 +1100,10 @@ NSR_ProcessRx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
assert(initialised);
/* Must match IP address AND port number */
if (find_slot2(remote_addr, &slot) == 2) {
/* Avoid unnecessary lookup if the packet cannot be a response from our
source. Otherwise, it must match both IP address and port number. */
if (NTP_LVM_TO_MODE(message->lvm) != MODE_CLIENT &&
find_slot2(remote_addr, &slot) == 2) {
record = get_record(slot);
if (!NCR_ProcessRxKnown(record->data, local_addr, rx_ts, message, length))
@ -1137,8 +1139,10 @@ NSR_ProcessTx(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
SourceRecord *record;
int slot;
/* Must match IP address AND port number */
if (find_slot2(remote_addr, &slot) == 2) {
/* Avoid unnecessary lookup if the packet cannot be a request to our
source. Otherwise, it must match both IP address and port number. */
if (NTP_LVM_TO_MODE(message->lvm) != MODE_SERVER &&
find_slot2(remote_addr, &slot) == 2) {
record = get_record(slot);
NCR_ProcessTxKnown(record->data, local_addr, tx_ts, message, length);
} else {

9
test/unit/ntp_sources.c
View file

@ -110,7 +110,7 @@ change_remote_address(NCR_Instance inst, NTP_Remote_Address *remote_addr, int nt
void
test_unit(void)
{
char source_line[] = "127.0.0.1 offline", conf[] = "port 0", name[64], msg[1];
char source_line[] = "127.0.0.1 offline", conf[] = "port 0", name[64];
int i, j, k, slot, found, pool, prev_n;
uint32_t hash = 0, conf_id;
NTP_Remote_Address addrs[256], addr;
@ -120,6 +120,7 @@ test_unit(void)
RPT_ActivityReport report;
CPS_NTP_Source source;
NSR_Status status;
NTP_Packet msg;
CNF_Initialise(0, 0);
CNF_ParseLine(NULL, 1, conf);
@ -272,12 +273,14 @@ test_unit(void)
switch (random() % 5) {
case 0:
msg.lvm = NTP_LVM(0, NTP_VERSION, random() % 2 ? MODE_CLIENT : MODE_SERVER);
NSR_ProcessTx(get_record(slot)->remote_addr, &local_addr,
&local_ts, (NTP_Packet *)msg, 0);
&local_ts, &msg, 0);
break;
case 1:
msg.lvm = NTP_LVM(0, NTP_VERSION, random() % 2 ? MODE_CLIENT : MODE_SERVER);
NSR_ProcessRx(get_record(slot)->remote_addr, &local_addr,
&local_ts, (NTP_Packet *)msg, 0);
&local_ts, &msg, 0);
break;
case 2:
NSR_HandleBadSource(&get_record(slot)->remote_addr->ip_addr);