From: René Scharfe <l.s.r@web.de>
Date: Thu, 06 Apr 2017 20:20:49 GMT
Subject: Re: [PATCH v5 1/4] p0004-read-tree: perf test to time read-tree
Message-ID: <6937b76e-9bbf-7ce5-8605-e09f556f8a26@web.de>
In-Reply-To: <20170405173809.3098-2-git@jeffhostetler.com>

Am 05.04.2017 um 19:38 schrieb git@jeffhostetler.com:
> From: Jeff Hostetler <jeffhost@microsoft.com>
> 
> Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
> ---
>  t/perf/p0004-read-tree.sh | 116 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 116 insertions(+)
>  create mode 100755 t/perf/p0004-read-tree.sh
> 
> diff --git a/t/perf/p0004-read-tree.sh b/t/perf/p0004-read-tree.sh
> new file mode 100755
> index 0000000..5d8bbf5
> --- /dev/null
> +++ b/t/perf/p0004-read-tree.sh
> @@ -0,0 +1,116 @@
> +#!/bin/sh
> +
> +test_description="Tests performance of read-tree"
> +
> +. ./perf-lib.sh
> +
> +test_perf_default_repo
> +test_checkout_worktree
> +
> +## usage: dir depth width files
> +make_paths () {
> +	for f in $(seq $4)
> +	do
> +		echo $1/file$f
> +	done;
> +	if test $2 -gt 0;
> +	then
> +		for w in $(seq $3)
> +		do
> +			make_paths $1/dir$w $(($2 - 1)) $3 $4
> +		done
> +	fi
> +	return 0
> +}

"make_paths xxx_dir_xxx 5 10 9" takes more than a minute for me.
Providing its results as a file would be quicker but less flexible.
The following command prints the same result in less than a second.

	awk -v dir=xxx_dir_xxx -v depth=5 -v width=10 -v files=9 '
        	function make_paths(dir, depth, width, files,  i)
	        {
        	        for (i = 1; i <= files; i++) {
	                        print dir "/file" i
        	        }
	                if (depth > 0) {
        	                for (i = 1; i <= width; i++) {
	                                make_paths(dir "/dir" i, depth - 1, width, files)
        	                }
                	}
	        }
	        END {make_paths(dir, depth, width, files)}
	' </dev/null

It's faster because it avoids calling seq thousands of times.

> +
> +fill_index () {
> +	make_paths $1 $2 $3 $4 |
> +	sed "s/^/100644 $EMPTY_BLOB	/" |

You could add the prefix to the script above and avoid this sed call
as well.

René