Fix blocks number calculation for Flat PA

[iboiko-habana]

Fix blocks number calculation for Flat PA via adding empty table_block (#158)

[madamczykhabana]

Please combine those two if statements. Something like:

if len(block_table) == 0:
    block_number = _PAD_BLOCK_ID
    block_table = []
    slot = next(dummy_slots)
else:
    block_number = block_table[position // self.block_size]
    block_offset = position % self.block_size
    slot = block_number * self.block_size + block_offset

[madamczykhabana]

LGTM

[hlin99]

seq_group_metadata_list.extend(
self.create_dummy_seq_group_metadata(0, 0, is_prompt)
for _ in range(batch_size_padding))

this piece of code introduces metadata certation in loop, and observe 10% perf drop. is this code change intentional?

[iboiko-habana]

@hlin99 Thanks. Please re-check perf with #301

[hlin99]

`` @hlin99 Thanks. Please re-check perf with #301

Unfortunately, performance has not improved, and the data looks identical before and after applying the patch. It seems that dummy creation and list extension are not the root cause of the performance drop. Instead, the issue appears to stem from changes to the dummy metadata, which are affecting subsequent calling path changes.