Server slowing down with each request (requests are identical)

[ruped]

Pre-Prerequisite

Thanks to all the contributors for all the great work on llama.cpp!

Prerequisites

• I am running the latest code. Development is very rapid so there are no tagged versions as of now.
• I carefully followed the README.md.
• I searched using keywords relevant to my issue to make sure that I am creating a new issue that is not already open (or closed).
• I reviewed the Discussions, and have a new bug or useful enhancement to share.

Expected Behaviour

• Identical requests to the server should take similar amounts of time
  • I made 4 identical requests to the server, sequential with 1 second pause after each.

Current Behaviour

• Each request to the server takes longer to process.
• Note particularly the prompt_eval time gets much slower.
• Also: After the last request it says "slot 3 released (1155 tokens in cache)" - is that expected?
  • Why should there be data in the cache after the slot has been released and there are no active requests?

print_timings: prompt eval time =    1110.28 ms /  1134 tokens (    0.98 ms per token,  1021.37 tokens per second)
print_timings:        eval time =     561.83 ms /    20 runs   (   28.09 ms per token,    35.60 tokens per second)
print_timings:       total time =    1672.10 ms
slot 0 released (1155 tokens in cache)

slot 1 is processing [task id: 1]
slot 1 : kv cache rm - [0, end)
print_timings: prompt eval time =    1483.84 ms /  1134 tokens (    1.31 ms per token,   764.23 tokens per second)
print_timings:        eval time =     591.59 ms /    20 runs   (   29.58 ms per token,    33.81 tokens per second)
print_timings:       total time =    2075.43 ms
slot 1 released (1155 tokens in cache)

slot 2 is processing [task id: 2]
slot 2 : kv cache rm - [0, end)
print_timings: prompt eval time =    1764.20 ms /  1134 tokens (    1.56 ms per token,   642.78 tokens per second)
print_timings:        eval time =     618.07 ms /    20 runs   (   30.90 ms per token,    32.36 tokens per second)
print_timings:       total time =    2382.28 ms
slot 2 released (1155 tokens in cache)

slot 3 is processing [task id: 3]
slot 3 : kv cache rm - [0, end)
print_timings: prompt eval time =    2229.91 ms /  1134 tokens (    1.97 ms per token,   508.54 tokens per second)
print_timings:        eval time =     642.50 ms /    20 runs   (   32.12 ms per token,    31.13 tokens per second)
print_timings:       total time =    2872.41 ms
slot 3 released (1155 tokens in cache)

Environment and Context

• Physical (or virtual) hardware you are using: Physical hardware, Nvidia GPU

• Operating System: Linux

Failure Information (for bugs)

Please help provide information about the failure / bug.

Steps to Reproduce

• Start server

 (./build/bin/server -m ./ggml-model-q4.bin -ngl 9999  --ctx-size 8000 --host 0.0.0.0 --port 7777 --cont-batching --parallel 4)

• Make requests to server with curl sequentially (one at a time).

Thanks!

[FSSRepo]

It's not something that only happens with the server example; it also occurs with the ./main example, so it's an internal issue with the function that has a regression in performance as the context is filled.

[ruped]

Thanks for confirming @FSSRepo.

Should this be moved to bug-confirmed status? Or is that not really necessary for it?

[ggerganov]

It's not something that only happens with the server example; it also occurs with the ./main example, so it's an internal issue with the function that has a regression in performance as the context is filled.

If the cache is cleared correctly, it would not be slower after each request, so there seems to be a server-specific problem.

[FSSRepo]

Upon reviewing carefully, it seems so, although I believe that only happens if the requests are launched at the same time in different slots.

Too remember the token speed it's a mean from start the task to end the task.

Sorry for edit your comment, i sometimes confuse quote with edit in GitHub Android App

[LoopControl]

I've also seen this issue with ./server when used with -cb and -np flags on my Linux system.

The first request runs at full expected speed but the following requests generate slower (with identical prompt).

[github-actions]

This issue was closed because it has been inactive for 14 days since being marked as stale.

[recreationalviking]

Was this fixed? I'm still having this issue.

[ggerganov]

I think it should be fixed. If you reproduce it, please provide the curl command that you are using to test