| commit | 55a9651d26a6b88c68445e7d6c9f511d1207cbd8 | [log] [tgz] |
|---|---|---|
| author | Jacob Vosmaer <jacob@gitlab.com> | Tue Dec 14 20:46:26 2021 +0100 |
| committer | Junio C Hamano <gitster@pobox.com> | Wed Dec 15 11:51:18 2021 -0800 |
| tree | 7ba21f99e6540f7f2a5f3cd35950183c9b5a8d00 | |
| parent | 69a9c10c95e28df457e33b3c7400b16caf2e2962 [diff] |
upload-pack.c: increase output buffer size When serving a fetch, git upload-pack copies data from a git pack-objects stdout pipe to its stdout. This commit increases the size of the buffer used for that copying from 8192 to 65515, the maximum sideband-64k packet size. Previously, this buffer was allocated on the stack. Because the new buffer size is nearly 64KB, we switch this to a heap allocation. On GitLab.com we use GitLab's pack-objects cache which does writes of 65515 bytes. Because of the default 8KB buffer size, propagating these cache writes requires 8 pipe reads and 8 pipe writes from git-upload-pack, and 8 pipe reads from Gitaly (our Git RPC service). If we increase the size of the buffer to the maximum Git packet size, we need only 1 pipe read and 1 pipe write in git-upload-pack, and 1 pipe read in Gitaly to transfer the same amount of data. In benchmarks with a pure fetch and 100% cache hit rate workload we are seeing CPU utilization reductions of over 30%. Signed-off-by: Jacob Vosmaer <jacob@gitlab.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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