# [PATCH] merge: optimization to skip evaluate_result for single strategy 2 messages from 2020-05-18 to 2020-05-18. Participants: anng.sw@gmail.com, Junio C Hamano. Thread: https://gitlist.dev/t/53496 ## anng.sw@gmail.com, 2020-05-18 15:36 Subject: [PATCH] merge: optimization to skip evaluate_result for single strategy Message-ID: <20200518153613.17497-1-anng.sw@gmail.com> URL: https://gitlist.dev/e/20200518153613.17497-1-anng.sw%40gmail.com ``` From: Andrew Ng For a merge with a single strategy, the result of evaluate_result() is effectively not used and therefore is not needed, so avoid altogether. On Windows, this optimization can half the time required to perform a recursive merge of a single commit with the LLVM repo. Signed-off-by: Andrew Ng --- builtin/merge.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/builtin/merge.c b/builtin/merge.c index ca6a5dc4bf..7da707bf55 100644 --- a/builtin/merge.c +++ b/builtin/merge.c @@ -1656,7 +1656,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix) } merge_was_ok = 1; } - cnt = evaluate_result(); + cnt = (use_strategies_nr > 1) ? evaluate_result() : 0; if (best_cnt <= 0 || cnt <= best_cnt) { best_strategy = use_strategies[i]->name; best_cnt = cnt; -- 2.26.2.windows.1 ``` ## Junio C Hamano, 2020-05-18 17:23 Subject: Re: [PATCH] merge: optimization to skip evaluate_result for single strategy Message-ID: URL: https://gitlist.dev/e/xmqqk11940o9.fsf%40gitster.c.googlers.com In-Reply-To: <20200518153613.17497-1-anng.sw@gmail.com> ``` anng.sw@gmail.com writes: > From: Andrew Ng > > For a merge with a single strategy, the result of evaluate_result() is > effectively not used and therefore is not needed, so avoid altogether. Excellent observation. > On Windows, this optimization can half the time required to perform a s/half/halve/ > recursive merge of a single commit with the LLVM repo. > > Signed-off-by: Andrew Ng > --- > builtin/merge.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/builtin/merge.c b/builtin/merge.c > index ca6a5dc4bf..7da707bf55 100644 > --- a/builtin/merge.c > +++ b/builtin/merge.c > @@ -1656,7 +1656,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix) > } > merge_was_ok = 1; > } > - cnt = evaluate_result(); > + cnt = (use_strategies_nr > 1) ? evaluate_result() : 0; As best_cnt is initialized to (-1), any value would trigger the logic to nominate the current one as "best so far", and 0 is just as good as it gets ;-) And we'll finish the loop soon after doing so. Looks good. > if (best_cnt <= 0 || cnt <= best_cnt) { > best_strategy = use_strategies[i]->name; > best_cnt = cnt; ```