I have a ntp server, I found that when number of packet become large, the server seems overloaded which many packet is being dropped. So could you tell me how to tune sysctl.conf in order to optimize its ability for the server to handle large amount of UDP packets
Did you try searching? The information you provide is not very detailed. So, it be difficult to judge as to what causes your server to overload.
Depending on the root cause of the overload you experience there may be different solutions. Two (random) suggestions for further reading:
What’s the specifications, NTP server software configuration, and how much traffic you were seeing which caused packet drop?
Nobody can tell what’s going on without knowing any details.
packet drop increase sharply when bandwidth more than 20mbit/s(real bandwidth, not net speed). after optimizing settings the problem still exist, so i think is OS problem(I previously use slackware due to its reputation of lightweight which i think it may increase performance.) However NTP performance actually decrease compared to mainstream OS like Ubuntu because after reinstalling the server with Ubuntu the problem disappear completely.