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From: Jeff King <peff@peff.net>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, "Junio C Hamano" <gitster@pobox.com>,
	"Johannes Sixt" <j6t@kdbg.org>,
	"Øystein Walle" <oystwa@gmail.com>
Subject: Re: [PATCH 6/8] generate-cmdlist.sh: replace for loop by printf's auto-repeat feature
Date: Thu, 21 Oct 2021 10:42:51 -0400	[thread overview]
Message-ID: <YXF8a7OoStzdEwZF@coredump.intra.peff.net> (raw)
In-Reply-To: <patch-6.8-e0b11514b8d-20211020T183533Z-avarab@gmail.com>

On Wed, Oct 20, 2021 at 08:39:57PM +0200, Ævar Arnfjörð Bjarmason wrote:

> From: Johannes Sixt <j6t@kdbg.org>
> 
> This is just a small code reduction. There is a small probability that
> the new code breaks when the category list is empty. But that would be
> noticed during the compile step.
> 
> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>  generate-cmdlist.sh | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/generate-cmdlist.sh b/generate-cmdlist.sh
> index e517c33710a..a1ab2b1f077 100755
> --- a/generate-cmdlist.sh
> +++ b/generate-cmdlist.sh
> @@ -67,10 +67,7 @@ print_command_list () {
>  	while read cmd rest
>  	do
>  		printf "	{ \"$cmd\", $(get_synopsis $cmd), 0"
> -		for cat in $(echo "$rest" | get_category_line)
> -		do
> -			printf " | CAT_$cat"
> -		done
> +		printf " | CAT_%s" $(echo "$rest" | get_category_line)
>  		echo " },"

I think this is fine, but regardless of what happens in patch 7, it's
probably worth dropping this get_category_line call. All it does is sort
and de-dup the tokens in $rest, but we don't care because we're just
OR-ing them together. And of the 3 processes spawned by each loop, it is
responsible for 2 of them.

Even if this loop is broken out into individual bits of Makefile
snippet, avoiding the extra processes is worth doing.

The patch below gives me:

  $ git show HEAD:generate-cmdlist.sh >generate-cmdlist.sh.old
  $ hyperfine --warmup 1 -L s ,.old -p 'make clean' 'sh generate-cmdlist.sh{s} command-list.txt'
  Benchmark #1: sh generate-cmdlist.sh command-list.txt
    Time (mean ± σ):     591.3 ms ±  31.5 ms    [User: 392.9 ms, System: 243.7 ms]
    Range (min … max):   543.7 ms … 630.6 ms    10 runs
   
  Benchmark #2: sh generate-cmdlist.sh.old command-list.txt
    Time (mean ± σ):      1.236 s ±  0.060 s    [User: 1.100 s, System: 0.556 s]
    Range (min … max):    1.089 s …  1.275 s    10 runs
   
  Summary
    'sh generate-cmdlist.sh command-list.txt' ran
      2.09 ± 0.15 times faster than 'sh generate-cmdlist.sh.old command-list.txt'

---
diff --git a/generate-cmdlist.sh b/generate-cmdlist.sh
index a1ab2b1f07..fab9e6a671 100755
--- a/generate-cmdlist.sh
+++ b/generate-cmdlist.sh
@@ -67,7 +67,7 @@ print_command_list () {
 	while read cmd rest
 	do
 		printf "	{ \"$cmd\", $(get_synopsis $cmd), 0"
-		printf " | CAT_%s" $(echo "$rest" | get_category_line)
+		printf " | CAT_%s" $rest
 		echo " },"
 	done
 	echo "};"

I think you could also delete get_category_line, as it was inlined in
the other caller.

-Peff

  reply	other threads:[~2021-10-21 14:42 UTC|newest]

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-24 13:16 Why the Makefile is so eager to re-build & re-link Ævar Arnfjörð Bjarmason
2021-06-24 15:16 ` Jeff King
2021-06-24 15:28   ` Ævar Arnfjörð Bjarmason
2021-06-24 21:30   ` Johannes Sixt
2021-06-25  8:34     ` Ævar Arnfjörð Bjarmason
2021-06-25  9:01       ` Ævar Arnfjörð Bjarmason
2021-06-29  2:13       ` Jeff King
2021-10-20 18:39         ` [PATCH 0/8] Makefile: make command-list.h 2-5x as fast with -jN Ævar Arnfjörð Bjarmason
2021-10-20 18:39           ` [PATCH 1/8] command-list.txt: sort with "LC_ALL=C sort" Ævar Arnfjörð Bjarmason
2021-10-20 18:39           ` [PATCH 2/8] generate-cmdlist.sh: trivial whitespace change Ævar Arnfjörð Bjarmason
2021-10-20 18:39           ` [PATCH 3/8] generate-cmdlist.sh: spawn fewer processes Ævar Arnfjörð Bjarmason
2021-10-20 18:39           ` [PATCH 4/8] generate-cmdlist.sh: don't call get_categories() from category_list() Ævar Arnfjörð Bjarmason
2021-10-20 18:39           ` [PATCH 5/8] generate-cmdlist.sh: run "grep | sort", not "sort | grep" Ævar Arnfjörð Bjarmason
2021-10-20 18:39           ` [PATCH 6/8] generate-cmdlist.sh: replace for loop by printf's auto-repeat feature Ævar Arnfjörð Bjarmason
2021-10-21 14:42             ` Jeff King [this message]
2021-10-21 16:25               ` Jeff King
2021-10-20 18:39           ` [PATCH 7/8] Makefile: stop having command-list.h depend on a wildcard Ævar Arnfjörð Bjarmason
2021-10-21 14:45             ` Jeff King
2021-10-21 18:24               ` Junio C Hamano
2021-10-21 22:46             ` Øystein Walle
2021-10-20 18:39           ` [PATCH 8/8] Makefile: assert correct generate-cmdlist.sh output Ævar Arnfjörð Bjarmason
2021-10-20 20:35           ` [PATCH 0/8] Makefile: make command-list.h 2-5x as fast with -jN Jeff King
2021-10-20 21:31             ` Taylor Blau
2021-10-20 23:14               ` Ævar Arnfjörð Bjarmason
2021-10-20 23:46                 ` Jeff King
2021-10-21  0:48                   ` Ævar Arnfjörð Bjarmason
2021-10-21  2:20                     ` Taylor Blau
2021-10-22 12:37                       ` Ævar Arnfjörð Bjarmason
2021-10-21 14:34                     ` Jeff King
2021-10-21 22:34                       ` Junio C Hamano
2021-10-22 10:51                       ` Ævar Arnfjörð Bjarmason
2021-10-22 18:31                         ` Jeff King
2021-10-22 20:50                           ` Ævar Arnfjörð Bjarmason
2021-10-21  5:39                 ` Eric Sunshine
2021-10-22 19:36           ` [PATCH v2 00/10] Makefile: make generate-cmdlist.sh much faster Ævar Arnfjörð Bjarmason
2021-10-22 19:36             ` [PATCH v2 01/10] command-list.txt: sort with "LC_ALL=C sort" Ævar Arnfjörð Bjarmason
2021-10-25 18:29               ` Junio C Hamano
2021-10-25 21:22                 ` Ævar Arnfjörð Bjarmason
2021-10-25 21:26                   ` Junio C Hamano
2021-10-22 19:36             ` [PATCH v2 02/10] generate-cmdlist.sh: trivial whitespace change Ævar Arnfjörð Bjarmason
2021-10-22 19:36             ` [PATCH v2 03/10] generate-cmdlist.sh: spawn fewer processes Ævar Arnfjörð Bjarmason
2021-10-22 19:36             ` [PATCH v2 04/10] generate-cmdlist.sh: don't call get_categories() from category_list() Ævar Arnfjörð Bjarmason
2021-10-22 19:36             ` [PATCH v2 05/10] generate-cmdlist.sh: run "grep | sort", not "sort | grep" Ævar Arnfjörð Bjarmason
2021-10-22 19:36             ` [PATCH v2 06/10] generate-cmdlist.sh: replace for loop by printf's auto-repeat feature Ævar Arnfjörð Bjarmason
2021-10-22 19:36             ` [PATCH v2 07/10] generate-cmdlist.sh: stop sorting category lines Ævar Arnfjörð Bjarmason
2021-10-25 16:39               ` Jeff King
2021-10-22 19:36             ` [PATCH v2 08/10] generate-cmdlist.sh: do not shell out to "sed" Ævar Arnfjörð Bjarmason
2021-10-25 16:46               ` Jeff King
2021-10-25 17:52                 ` Jeff King
2021-10-22 19:36             ` [PATCH v2 09/10] generate-cmdlist.sh: replace "grep' invocation with a shell version Ævar Arnfjörð Bjarmason
2021-10-23 22:19               ` Junio C Hamano
2021-10-23 22:26               ` Junio C Hamano
2021-10-22 19:36             ` [PATCH v2 10/10] generate-cmdlist.sh: replace "cut", "tr" and "grep" with pure-shell Ævar Arnfjörð Bjarmason
2021-10-23 22:26               ` Junio C Hamano
2021-10-22 21:20             ` [PATCH v2 00/10] Makefile: make generate-cmdlist.sh much faster Taylor Blau
2021-10-23 22:34             ` Junio C Hamano
2021-10-25 16:57             ` Jeff King
2021-11-05 14:07             ` [PATCH v3 00/10] generate-cmdlist.sh: make it (and "make") run faster Ævar Arnfjörð Bjarmason
2021-11-05 14:07               ` [PATCH v3 01/10] command-list.txt: sort with "LC_ALL=C sort" Ævar Arnfjörð Bjarmason
2021-11-05 22:45                 ` Junio C Hamano
2021-11-06  4:26                   ` Ævar Arnfjörð Bjarmason
2021-11-08 19:18                     ` Junio C Hamano
2021-11-05 14:08               ` [PATCH v3 02/10] generate-cmdlist.sh: trivial whitespace change Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 03/10] generate-cmdlist.sh: spawn fewer processes Ævar Arnfjörð Bjarmason
2021-11-05 22:47                 ` Junio C Hamano
2021-11-06  4:23                   ` Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 04/10] generate-cmdlist.sh: don't call get_categories() from category_list() Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 05/10] generate-cmdlist.sh: run "grep | sort", not "sort | grep" Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 06/10] generate-cmdlist.sh: replace for loop by printf's auto-repeat feature Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 07/10] generate-cmdlist.sh: stop sorting category lines Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 08/10] generate-cmdlist.sh: do not shell out to "sed" Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 09/10] generate-cmdlist.sh: replace "grep' invocation with a shell version Ævar Arnfjörð Bjarmason
2021-11-05 14:08               ` [PATCH v3 10/10] generate-cmdlist.sh: don't parse command-list.txt thrice Ævar Arnfjörð Bjarmason
2021-06-25 21:17   ` Why the Makefile is so eager to re-build & re-link Felipe Contreras
2021-06-29  5:04   ` Eric Sunshine
2021-06-24 23:35 ` Øystein Walle
2021-06-24 23:39   ` Øystein Walle
2021-06-25  0:11   ` Ævar Arnfjörð Bjarmason
2021-07-02 11:58 ` [PATCH] Documentation/Makefile: don't re-build on 'git version' changes Ævar Arnfjörð Bjarmason
2021-07-02 15:53   ` Junio C Hamano
2021-07-03 11:58     ` Ævar Arnfjörð Bjarmason
2021-07-05 19:48       ` Junio C Hamano
2021-07-03  1:05   ` Felipe Contreras
2021-07-03 12:03     ` Ævar Arnfjörð Bjarmason
2021-07-03 18:56       ` Felipe Contreras
2021-07-05 19:38       ` Junio C Hamano
2021-07-06 22:25         ` Felipe Contreras

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