Re: [RFC] Cache negative delta pairs
From: Jeff King <hidden>
Date: 2016-06-15 22:42:31
Subsystem:
the rest · Maintainer:
Linus Torvalds
Possibly related (same subject, not in this thread)
- 2016-06-15 · Re: [RFC] Cache negative delta pairs · Junio C Hamano <hidden>
- 2016-06-15 · Re: [RFC] Cache negative delta pairs · Junio C Hamano <hidden>
- 2016-06-15 · Re: [RFC] Cache negative delta pairs · Junio C Hamano <hidden>
- 2016-06-15 · Re: [RFC] Cache negative delta pairs · Junio C Hamano <hidden>
On Wed, Jun 28, 2006 at 11:58:49PM -0400, Jeff King wrote:
about 2.7M. The linux-2.6 cache is 22M. [...] - correctness. Currently the code uses the output of try_delta for negative caching. Should the cache checking be moved inside try_delta instead? This would give more control over which reasons to mark a
I tried moving the cache check/mark to wrap the call to create_delta in try_delta. The speedup is the same (since all of the CPU time is spent in create_delta anyway), and the linux-2.6 cache size dropped to 18M. I also think this is probably more correct (it ignores every reason not to delta EXCEPT create_delta failing). The distribution of the window parameter 'j' is similarly uniform: 44900 j=2 44907 j=3 44943 j=1 45001 j=4 45014 j=5 45023 j=6 45063 j=7 45158 j=8 45288 j=9 45466 j=10 Patch on top of my other one is below. -Peff -- >8 -- pack-objects: move delta-cache check/mark closer to create_delta Signed-off-by: Jeff King <redacted> --- pack-objects.c | 15 ++++++--------- 1 files changed, 6 insertions(+), 9 deletions(-)
diff --git a/pack-objects.c b/pack-objects.c
index 46b9775..83ccc8a 100644
--- a/pack-objects.c
+++ b/pack-objects.c@@ -1014,9 +1014,13 @@ static int try_delta(struct unpacked *tr if (sizediff >= max_size) return 0; + if (delta_cache_check(src->entry->sha1, trg->entry->sha1)) + return 0; delta_buf = create_delta(src_index, trg->data, size, &delta_size, max_size); - if (!delta_buf) + if (!delta_buf) { + delta_cache_mark(src->entry->sha1, trg->entry->sha1); return 0; + } trg_entry->delta = src_entry; trg_entry->delta_size = delta_size;
@@ -1084,21 +1088,14 @@ static void find_deltas(struct object_en j = window; while (--j > 0) { unsigned int other_idx = idx + j; - int r; struct unpacked *m; if (other_idx >= window) other_idx -= window; m = array + other_idx; if (!m->entry) break; - if (delta_cache_check(n->entry->sha1, m->entry->sha1)) - continue; - r = try_delta(n, m, m->index, depth); - if (r < 0) + if (try_delta(n, m, m->index, depth) < 0) break; - if (r == 0) - delta_cache_mark(n->entry->sha1, - m->entry->sha1); } /* if we made n a delta, and if n is already at max * depth, leaving it in the window is pointless. we
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1.4.1.rc1.g0458-dirty