On 1/31/24 12:56 PM, Olivier Langlois wrote: > On Wed, 2024-01-31 at 12:59 -0500, Olivier Langlois wrote: >> On Wed, 2024-01-31 at 10:32 -0700, Jens Axboe wrote: >>> >>> Thanks for testing! >>> >>> Any chance that you could run some tests with and without NAPI that >>> help >>> validate that it actually works? That part is what I'm most >>> interested >>> in, not too worried about the stability of it as I have scrutinized >>> it >>> pretty close already. >>> >> >> There is maybe a test that I can perform. The data that I receive is >> timestamped. I have a small test program that checks the age of the >> updates on their reception... >> >> I would expect that it should be possible to perceive the busy >> polling >> effect by comparing the average update age with and without the >> feature >> enabled... >> >> A word of warning... The service that my client is connecting to has >> relocated recently. I used to have an RTT of about 8mSec with it to >> about 400-500 mSec today... >> >> because of the huge RTT, I am unsure that the test is going to be >> conclusive at all... >> >> However, I am also in the process of relocating my client closer to >> the >> service. If you can wait a week or so, I should able to do that test >> with a RTT < 1 mSec... >> >> Beside that, I could redo the same test that Stefan did with the ping >> client/server setup but would that test add any value to the current >> collective knowledge? >> >> I'll do the update age test when I restart my client and I'll report >> back the result but my expectations aren't very high that it is going >> to be conclusive due to the huge RTT. >> >> > As I expected, the busy polling difference in the update age test is so > small compared to the RTT that the result is inconclusive, IMHO... > > The number of collected updates to build the stats is 500. > > System clocks are assumed to be synchronized and the RTT is the > difference between the local time and the update timestamp. > Actually, it may be more accurate to say that the displayed RTT values > are in fact TT... > > latency NO napi busy poll: > [2024-01-31 11:28:34] INFO Main/processCollectedData rtt > min/avg/max/mdev = 74.509/76.752/115.969/3.110 ms > > latency napi busy poll: > [2024-01-31 11:33:05] INFO Main/processCollectedData rtt > min/avg/max/mdev = 75.347/76.740/134.588/1.648 ms > > I'll redo the test once my RTT is closer to 1mSec. The relative gain > should be more impressive... Also happy to try and run it here, if you can share it? If not I have some other stuff I can try as well, with netbench. -- Jens Axboe
