D$: fix two noisy-drop performance bugs #2739
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If the C-channel TSHR is occupied and we wish to evict a clean line, just silently drop the line rather than waiting for the TSHR to become available. Otherwise, we'd stretch the miss latency.
d_address_inc is only valid when d.valid is true (or, more precisely, when d.bits.opcode is valid). So, we weren't unblocking the core on the most optimal cycle in some cases. This only seems to happen in practice with noisy drops, since there d.bits.opcode is sometimes ReleaseAck, whereas otherwise d.bits.opcode is almost always GrantData. Not a correctness issue.
hcook
approved these changes
Nov 21, 2020
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Type of change: bug report | feature request | other enhancement
Impact: no functional change | API addition (no impact on existing code) | API modification
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