sampling : avoid expensive softmax during greedy sampling #9605
  Add this suggestion to a batch that can be applied as a single commit.
  This suggestion is invalid because no changes were made to the code.
  Suggestions cannot be applied while the pull request is closed.
  Suggestions cannot be applied while viewing a subset of changes.
  Only one suggestion per line can be applied in a batch.
  Add this suggestion to a batch that can be applied as a single commit.
  Applying suggestions on deleted lines is not supported.
  You must change the existing code in this line in order to create a valid suggestion.
  Outdated suggestions cannot be applied.
  This suggestion has been applied or marked resolved.
  Suggestions cannot be applied from pending reviews.
  Suggestions cannot be applied on multi-line comments.
  Suggestions cannot be applied while the pull request is queued to merge.
  Suggestion cannot be applied right now. Please check back later.
  
    
  
    
fix #9530
When the temperature is non-positive, we can simply sample greedily the token with the highest logit. But in some cases, the probs of the secondary tokens are also required (e.g.
llama-serverto display candidate probs,llama-speculativeto peform stochastic speculative sampling). In such cases, we first filter the the topsparams.n_probstokens via atop-ksampler and then apply softmax to them in order to avoid sorting the full vocabulary.Also add perf timings to
test-samplingto keep track of the performance of the samplers.ggml-ci