From: Jacob Vosmaer <jacob@gitlab.com>
To: git@vger.kernel.org
Cc: Jacob Vosmaer <jacob@gitlab.com>
Subject: [PATCH 1/1] upload-pack.c: make output buffer size configurable
Date: Mon, 13 Dec 2021 14:23:45 +0100 [thread overview]
Message-ID: <20211213132345.26310-2-jacob@gitlab.com> (raw)
In-Reply-To: <20211213132345.26310-1-jacob@gitlab.com>
Add a new compile time constant UPLOAD_PACK_BUFFER_SIZE that makes the
size of the static buffer in output_state configurable.
The current size of the buffer is 8192+1. The '+1' is a technical
detail orthogonal to this change. 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>
---
upload-pack.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/upload-pack.c b/upload-pack.c
index c78d55bc67..b799fbe628 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -42,6 +42,10 @@
#define ALL_FLAGS (THEY_HAVE | OUR_REF | WANTED | COMMON_KNOWN | SHALLOW | \
NOT_SHALLOW | CLIENT_SHALLOW | HIDDEN_REF)
+#ifndef UPLOAD_PACK_BUFFER_SIZE
+#define UPLOAD_PACK_BUFFER_SIZE 8192
+#endif
+
/* Enum for allowed unadvertised object request (UOR) */
enum allow_uor {
/* Allow specifying sha1 if it is a ref tip. */
@@ -194,7 +198,7 @@ static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
}
struct output_state {
- char buffer[8193];
+ char buffer[UPLOAD_PACK_BUFFER_SIZE+1];
int used;
unsigned packfile_uris_started : 1;
unsigned packfile_started : 1;
--
2.33.0
next prev parent reply other threads:[~2021-12-13 13:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-13 13:23 [PATCH 0/1] Make upload-pack pack write size configurable Jacob Vosmaer
2021-12-13 13:23 ` Jacob Vosmaer [this message]
2021-12-14 12:08 ` [PATCH 1/1] upload-pack.c: make output buffer " Ævar Arnfjörð Bjarmason
2021-12-14 15:08 ` Jeff King
2021-12-14 19:46 ` [PATCH v2 0/1] upload-pack.c: increase output buffer size Jacob Vosmaer
2021-12-14 19:46 ` [PATCH v2 1/1] " Jacob Vosmaer
2021-12-14 20:41 ` Ævar Arnfjörð Bjarmason
2021-12-15 16:30 ` Jeff King
2021-12-15 19:50 ` Junio C Hamano
2021-12-15 19:59 ` rsbecker
2021-12-15 20:24 ` Jacob Vosmaer
2021-12-15 20:38 ` rsbecker
2021-12-15 20:45 ` Jacob Vosmaer
2021-12-15 21:34 ` rsbecker
2021-12-14 15:37 ` [PATCH 1/1] upload-pack.c: make output buffer size configurable Jeff King
2021-12-14 20:04 ` Jacob Vosmaer
2021-12-14 15:12 ` [PATCH 0/1] Make upload-pack pack write " Jeff King
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