Junio C Hamano <gitster@xxxxxxxxx> 于2021年7月13日周二 上午4:38写道：
>
> Christian Couder <christian.couder@xxxxxxxxx> writes:
>
> More importantly, why is such a fast-path even needed? Isn't it a
> sign that the ref-filter implementation is eating more cycles than
> it should for given set of placeholders? Do we know where the extra
> cycles goes?
>
> I find it somewhat alarming if we are talking about "fast-path"
> workaround before understanding why we are seeing slowdown in the
> first place.
There is no complete conclusion yet, but I try to use time and hyperfine test
for these commits (t/perf/* is not accurate enough):
----------------------------------------------------------------------------------------------------------------------------
| subject |
--batch-check (using hyperfine) | --batch(using time) |
----------------------------------------------------------------------------------------------------------------------------
|[GSOC] cat-file: use fast path when using default_format |
700ms | 25.450s |
----------------------------------------------------------------------------------------------------------------------------
|[GSOC] cat-file: re-implement --textconv, --filters options |
790ms | 29.933s |
----------------------------------------------------------------------------------------------------------------------------
|[GSOC] cat-file: reuse err buf in batch_object_write() |
770ms | 29.153s |
----------------------------------------------------------------------------------------------------------------------------
|[GSOC] cat-file: reuse ref-filter logic |
780ms | 29.412s |
----------------------------------------------------------------------------------------------------------------------------
|The third batch (upstream/master) |
640ms | 26.025s |
----------------------------------------------------------------------------------------------------------------------------
I think we their cost is indeed from "[GSOC] cat-file: reuse ref-filter logic".
But what causes the loss of performance needs further analysis.
Thanks.
--
ZheNing Hu
