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From: Jeff King <peff@peff.net>
To: git@vger.kernel.org
Subject: [PATCH 0/6] reuse on-disk deltas for fetches with bitmaps
Date: Fri, 17 Aug 2018 16:54:27 -0400	[thread overview]
Message-ID: <20180817205427.GA19580@sigill.intra.peff.net> (raw)

This series more aggressively reuses on-disk deltas to serve fetches
when reachability bitmaps tell us a more complete picture of what the
client has. That saves server CPU and results in smaller packs. See the
final patch for numbers and more discussion.

It's a resurrection of this very old series:

  https://public-inbox.org/git/20140326072215.GA31739@sigill.intra.peff.net/

The core idea is good, but it got left as "I should dig into this more
to see if we can do even better". In fact, I _did_ do some of that
digging, as you can see in the thread, so I'm mildly embarrassed not to
have reposted it before now.

We've been using that original at GitHub since 2014, which I think helps
demonstrate the correctness of the approach (and the numbers here and in
that thread show that performance is generally a net win over the status
quo).

I's rebased on top of the current master, since the original made some
assumptions about struct object_entry that are no longer true post-v2.18
(due to the struct-shrinking exercise). So I fixed that and a few other
rough edges. But that also means you're not getting code with 4-years of
production testing behind it. :)

The other really ugly thing in the original was the way it leaked
object_entry structs (though in practice that didn't really matter since
we needed them until the end of the program anyway). This version fixes
that.

  [1/6]: t/perf: factor boilerplate out of test_perf
  [2/6]: t/perf: factor out percent calculations
  [3/6]: t/perf: add infrastructure for measuring sizes
  [4/6]: t/perf: add perf tests for fetches from a bitmapped server
  [5/6]: pack-bitmap: save "have" bitmap from walk
  [6/6]: pack-objects: reuse on-disk deltas for thin "have" objects

 builtin/pack-objects.c             | 28 +++++++----
 pack-bitmap.c                      | 23 +++++++++-
 pack-bitmap.h                      |  7 +++
 pack-objects.c                     | 19 ++++++++
 pack-objects.h                     | 20 +++++++-
 t/perf/README                      | 25 ++++++++++
 t/perf/aggregate.perl              | 69 ++++++++++++++++++++++------
 t/perf/p5311-pack-bitmaps-fetch.sh | 45 ++++++++++++++++++
 t/perf/perf-lib.sh                 | 74 +++++++++++++++++++-----------
 9 files changed, 258 insertions(+), 52 deletions(-)
 create mode 100755 t/perf/p5311-pack-bitmaps-fetch.sh

-Peff

             reply	other threads:[~2018-08-17 20:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-17 20:54 Jeff King [this message]
2018-08-17 20:55 ` [PATCH 1/6] t/perf: factor boilerplate out of test_perf Jeff King
2018-08-17 20:55 ` [PATCH 2/6] t/perf: factor out percent calculations Jeff King
2018-08-17 20:56 ` [PATCH 3/6] t/perf: add infrastructure for measuring sizes Jeff King
2018-08-17 20:57 ` [PATCH 4/6] t/perf: add perf tests for fetches from a bitmapped server Jeff King
2018-08-17 20:59 ` [PATCH 5/6] pack-bitmap: save "have" bitmap from walk Jeff King
2018-08-17 22:39   ` Stefan Beller
2018-08-17 22:45     ` Jeff King
2018-08-17 21:06 ` [PATCH 6/6] pack-objects: reuse on-disk deltas for thin "have" objects Jeff King
2018-08-17 22:57   ` Stefan Beller
2018-08-17 23:32     ` Jeff King
2018-08-20 21:03   ` Junio C Hamano
2018-08-20 21:42     ` Jeff King
2018-08-21 19:06 ` [PATCH v2 0/6] reuse on-disk deltas for fetches with bitmaps Jeff King
2018-08-21 19:08   ` Jeff King
2018-08-21 19:34   ` Junio C Hamano
2018-08-21 19:51     ` Jeff King

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