GSOC, Git Blog 7
Week7 Performance Testing 2
This week I used performance flame graph at the suggestion of my mentor Christian to find out where my patch affected the performance of cat-file --batch. oid_object_info_extended() takes the largest proportion of time, it accounts for 90.28% and 41.60% in cat-file --batch and cat-file --batch-check respectively. Part of the reason is that oid_object_info_extended() is called twice in get_object() with my patch. I tried to revise its logic (WIP), the performance is improved when not using --textconv and --filters.
Ævar Arnfjörð Bjarmason gave me a good suggestion on performance regression: When we use the default format of git cat-file --batch-check or git cat-file --batch, we can directly print the meta-data of the object without going through the logic of ref-filter; When we use other format, use the logic in ref-filter.
In addition, Ævar Arnfjörð Bjarmason also suggests adding a performance test for git cat-file --batch, this can help us analyze and compare performance changes later.
第七周 性能测试 2
这周，在我的导师 Christian 的建议下，我使用了性能火焰图来查明我的补丁在哪些地方影响了 cat-file --batch 的性能。oid_object_info_extended() 占了最大的时间比例，在 cat-file --batch 和 cat-file --batch-check 中分别占 90.28% 和 41.60%。部分原因是，在我的补丁中，get_object() 调用了两次 oid_object_info_extended()。我尝试修改了它的逻辑（WIP），在不使用 --textconv 和 --filters 时性能有所提升。
Ævar Arnfjörð Bjarmason 针对性能回归给了我一个很好的建议：当我们使用 git cat-file --batch-check 或 git cat-file --batch 的默认格式时，可以直接打印对象的元数据，而不必经过 ref-filter 的逻辑；当我们使用其他格式时，再使用 ref-filter 的逻辑。
此外，Ævar Arnfjörð Bjarmason 还建议为 git cat-file --batch 添加一个性能测试，这可以帮助我们以后分析和比较性能变化。