Hi Todd, I'm trying several TCP Congestion algorithms here: westwood, highspeed, veno, etc.
No luck so far, but there are many more I haven't tried. I'm using this answer to change the TCP congestion algo: http://unix.stackexchange.com/a/278217 Does anyone know what TCP congestion algorithm is the best for low-latency? Or the best for the single message scenario I've described? *This looks like an important configuration for trading, when a single order needs to go out after some time and you don't want it to go out at a slower speed.* Thanks! -JC On Wednesday, April 12, 2017 at 5:38:40 PM UTC-5, Todd L. Montgomery wrote: > > Mike has the best point, I think. 30 seconds between sends will cause the > congestion window to close. Depending on what is in use (CUBIC vs. Reno), > this will change behavior. > > -- Todd > > On Wed, Apr 12, 2017 at 3:27 PM, Greg Young <[email protected] > <javascript:>> wrote: > >> You are likely measuring wrong and just have not figured out how yet. >> >> On Wed, Apr 12, 2017 at 8:56 PM, J Crawford <[email protected] >> <javascript:>> wrote: >> > The SO question has the source codes of a simple server and client that >> > demonstrate and isolate the problem. Basically I'm timing the latency >> of a >> > ping-pong (client-server-client) message. I start by sending one message >> > every 1 millisecond. I wait for 200k messages to be sent so that the >> HotSpot >> > has a chance to optimize the code. Then I change my pause time from 1 >> > millisecond to 30 seconds. For my surprise my write and read operation >> > become considerably slower. >> > >> > I don't think it is a JIT/HotSpot problem. I was able to pinpoint the >> slower >> > method to the native JNI calls to write (write0) and read. Even if I >> change >> > the pause from 1 millisecond to 1 second, problem persists. >> > >> > I was able to observe that on MacOS and Linux. >> > >> > Does anyone here have a clue of what can be happening? >> > >> > Note that I'm disabling Nagle's Algorithm with setTcpNoDelay(true). >> > >> > SO question with code and output: >> > >> http://stackoverflow.com/questions/43377600/socketchannel-why-if-i-write-msgs-quickly-the-latency-of-each-message-is-low-b >> > >> > Thanks! >> > >> > -JC >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups >> > "mechanical-sympathy" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an >> > email to [email protected] <javascript:> >> . >> > For more options, visit https://groups.google.com/d/optout. >> >> >> >> -- >> Studying for the Turing test >> >> -- >> You received this message because you are subscribed to the Google Groups >> "mechanical-sympathy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > -- You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
