[Cocci] [PATCH] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Cocci] [PATCH] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Sun, 25 Oct 2020 18:54:36 +0100

A disjunction is applied by this script for the semantic patch language.
This construct uses short-circuit evaluation. It has got the consequence
that the last element of the specified condition will only be checked
if all previous parts did not match. Such a technical detail leads to
a recommended ordering of condition parts if you would like to care for
optimal run time characteristics of SmPL code.

An usage incidence was determined for the specified identifiers in source
files from the software “Linux next-20201023” by another SmPL script.

See also:
Determination of an usage statistic for memory allocation calls
https://lore.kernel.org/cocci/2774601.u91sIFNy1E@sonne/

This analysis result indicates a clear ranking for such function calls.
Thus reorder the SmPL disjunction items according to their usage incidence.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 scripts/coccinelle/null/eno.cocci | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/scripts/coccinelle/null/eno.cocci b/scripts/coccinelle/null/eno.cocci
index 81584ff87956..969cab5116a9 100644
--- a/scripts/coccinelle/null/eno.cocci
+++ b/scripts/coccinelle/null/eno.cocci
@@ -17,8 +17,16 @@ virtual report
 @depends on patch@
 expression x,E;
 @@
-
-x = \(kmalloc\|kzalloc\|kcalloc\|kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache_alloc_node\|kmalloc_node\|kzalloc_node\)(...)
+ x =
+(kzalloc
+|kmalloc
+|kcalloc
+|kmem_cache_alloc
+|kmem_cache_zalloc
+|kzalloc_node
+|kmalloc_node
+|kmem_cache_alloc_node
+)(...)
 ... when != x = E
 - IS_ERR(x)
 + !x
@@ -27,8 +35,7 @@ x = \(kmalloc\|kzalloc\|kcalloc\|kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache
 expression x,E;
 position p1,p2;
 @@
-
-*x = \(kmalloc@p1\|kzalloc@p1\|kcalloc@p1\|kmem_cache_alloc@p1\|kmem_cache_zalloc@p1\|kmem_cache_alloc_node@p1\|kmalloc_node@p1\|kzalloc_node@p1\)(...)
+*x = \(kzalloc@p1\|kmalloc@p1\|kcalloc@p1\|kmem_cache_alloc@p1\|kmem_cache_zalloc@p1\|kzalloc_node@p1\|kmalloc_node@p1\|kmem_cache_alloc_node@p1\)(...)
 ... when != x = E
 * IS_ERR@p2(x)

--
2.29.1

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Re: [Cocci] [PATCH] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Julia Lawall]

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On Sun, 25 Oct 2020, Markus Elfring wrote:

> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sun, 25 Oct 2020 18:54:36 +0100
>
> A disjunction is applied by this script for the semantic patch language.
> This construct uses short-circuit evaluation. It has got the consequence
> that the last element of the specified condition will only be checked
> if all previous parts did not match. Such a technical detail leads to
> a recommended ordering of condition parts if you would like to care for
> optimal run time characteristics of SmPL code.
>
> An usage incidence was determined for the specified identifiers in source
> files from the software “Linux next-20201023” by another SmPL script.
>
> See also:
> Determination of an usage statistic for memory allocation calls
> https://lore.kernel.org/cocci/2774601.u91sIFNy1E@sonne/
>
> This analysis result indicates a clear ranking for such function calls.
> Thus reorder the SmPL disjunction items according to their usage incidence.

Did you actually test this before and after the change and see a
difference in performance?  On my laptop, I see absolutely no difference,
for the patch mode and for the context mode.  I didn't try the other
cases.

Before the change:

patch: 440.182u 2.049s 1:53.12 390.9%	0+0k 0+232io 4pf+0w
context: 392.931u 2.164s 1:41.53 389.1%	0+0k 432+360io 5pf+0w

After the change:

patch: 442.182u 2.090s 1:54.13 389.2%	0+0k 0+240io 4pf+0w
context: 392.742u 2.035s 1:41.37 389.4%	0+0k 0+360io 4pf+0w

julia

>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  scripts/coccinelle/null/eno.cocci | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/scripts/coccinelle/null/eno.cocci b/scripts/coccinelle/null/eno.cocci
> index 81584ff87956..969cab5116a9 100644
> --- a/scripts/coccinelle/null/eno.cocci
> +++ b/scripts/coccinelle/null/eno.cocci
> @@ -17,8 +17,16 @@ virtual report
>  @depends on patch@
>  expression x,E;
>  @@
> -
> -x = \(kmalloc\|kzalloc\|kcalloc\|kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache_alloc_node\|kmalloc_node\|kzalloc_node\)(...)
> + x =
> +(kzalloc
> +|kmalloc
> +|kcalloc
> +|kmem_cache_alloc
> +|kmem_cache_zalloc
> +|kzalloc_node
> +|kmalloc_node
> +|kmem_cache_alloc_node
> +)(...)
>  ... when != x = E
>  - IS_ERR(x)
>  + !x
> @@ -27,8 +35,7 @@ x = \(kmalloc\|kzalloc\|kcalloc\|kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache
>  expression x,E;
>  position p1,p2;
>  @@
> -
> -*x = \(kmalloc@p1\|kzalloc@p1\|kcalloc@p1\|kmem_cache_alloc@p1\|kmem_cache_zalloc@p1\|kmem_cache_alloc_node@p1\|kmalloc_node@p1\|kzalloc_node@p1\)(...)
> +*x = \(kzalloc@p1\|kmalloc@p1\|kcalloc@p1\|kmem_cache_alloc@p1\|kmem_cache_zalloc@p1\|kzalloc_node@p1\|kmalloc_node@p1\|kmem_cache_alloc_node@p1\)(...)
>  ... when != x = E
>  * IS_ERR@p2(x)
>
> --
> 2.29.1
>
> _______________________________________________
> Cocci mailing list
> Cocci@systeme.lip6.fr
> https://systeme.lip6.fr/mailman/listinfo/cocci
>

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Re: [Cocci] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Markus Elfring]

>> This analysis result indicates a clear ranking for such function calls.
>> Thus reorder the SmPL disjunction items according to their usage incidence.
>
> Did you actually test this before and after the change and see a
> difference in performance?

Would you become interested to configure a representative test environment
for safe comparisons of corresponding run time characteristics
of the affected software?


> On my laptop, I see absolutely no difference,
> for the patch mode and for the context mode.

Does such information trigger a desire to clarify involved aspects in more detail?

Regards,
Markus
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Re: [Cocci] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Julia Lawall]

On Sun, 25 Oct 2020, Markus Elfring wrote:

> >> This analysis result indicates a clear ranking for such function calls.
> >> Thus reorder the SmPL disjunction items according to their usage incidence.
> >
> > Did you actually test this before and after the change and see a
> > difference in performance?
>
> Would you become interested to configure a representative test environment
> for safe comparisons of corresponding run time characteristics
> of the affected software?

In what sense could the comparison possibly be unsafe?

Just use time and run spatch on whatever machine you want.  It's not that
complicated.

> > On my laptop, I see absolutely no difference,
> > for the patch mode and for the context mode.
>
> Does such information trigger a desire to clarify involved aspects in more detail?

Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz

julia
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Re: [Cocci] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Markus Elfring]

>> Would you become interested to configure a representative test environment
>> for safe comparisons of corresponding run time characteristics
>> of the affected software?
>
> In what sense could the comparison possibly be unsafe?

* Our test systems are obviously different.
  Thus concerns can be considered for reproducibility of test results
  on other possible configurations.

* We share only a tiny fraction of technical information which would probably
  be needed for “benchmarks”.


> Just use time and run spatch on whatever machine you want.

fring@Sonne:~/Projekte/Linux/next-patched>
elfring@Sonne:~/Projekte/Linux/next-patched> git checkout next-20201023 && XX=$(date) && time spatch -D patch --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno1.diff 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno1-errors.txt; YY=$(date) && echo "$XX | $YY"
…
real	2m54,266s
user	10m15,553s
sys	0m4,004s
So 25. Okt 20:53:56 CET 2020 | So 25. Okt 20:56:51 CET 2020
elfring@Sonne:~/Projekte/Linux/next-patched> git checkout next-20201023 && XX=$(date) && time spatch -D context --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno2.txt 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno2-errors.txt; YY=$(date) && echo "$XX | $YY"
…
real	2m38,494s
user	9m39,364s
sys	0m4,094s
So 25. Okt 20:58:05 CET 2020 | So 25. Okt 21:00:44 CET 2020
elfring@Sonne:~/Projekte/Linux/next-patched> git checkout optimise_disjunction_in_eno.cocci-1 && XX=$(date) && time spatch -D patch --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno3.diff 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno3-errors.txt; YY=$(date) && echo "$XX | $YY"
…
real	2m46,097s
user	10m15,467s
sys	0m3,984s
So 25. Okt 21:00:56 CET 2020 | So 25. Okt 21:03:42 CET 2020
elfring@Sonne:~/Projekte/Linux/next-patched> git checkout optimise_disjunction_in_eno.cocci-1 && XX=$(date) && time spatch -D context --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno4.txt 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno4-errors.txt; YY=$(date) && echo "$XX | $YY"
…
real	2m41,472s
user	9m37,492s
sys	0m3,834s
So 25. Okt 21:03:56 CET 2020 | So 25. Okt 21:06:37 CET 2020


> Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz

AMD Phenom(tm) II X4 850 Processor

Will any other aspects become relevant?

Regards,
Markus
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Re: [Cocci] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Julia Lawall]

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On Sun, 25 Oct 2020, Markus Elfring wrote:

> >> Would you become interested to configure a representative test environment
> >> for safe comparisons of corresponding run time characteristics
> >> of the affected software?
> >
> > In what sense could the comparison possibly be unsafe?
>
> * Our test systems are obviously different.
>   Thus concerns can be considered for reproducibility of test results
>   on other possible configurations.
>
> * We share only a tiny fraction of technical information which would probably
>   be needed for “benchmarks”.
>
>
> > Just use time and run spatch on whatever machine you want.
>
> fring@Sonne:~/Projekte/Linux/next-patched>
> elfring@Sonne:~/Projekte/Linux/next-patched> git checkout next-20201023 && XX=$(date) && time spatch -D patch --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno1.diff 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno1-errors.txt; YY=$(date) && echo "$XX | $YY"
> …
> real	2m54,266s
> user	10m15,553s
> sys	0m4,004s
> So 25. Okt 20:53:56 CET 2020 | So 25. Okt 20:56:51 CET 2020
> elfring@Sonne:~/Projekte/Linux/next-patched> git checkout next-20201023 && XX=$(date) && time spatch -D context --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno2.txt 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno2-errors.txt; YY=$(date) && echo "$XX | $YY"
> …
> real	2m38,494s
> user	9m39,364s
> sys	0m4,094s
> So 25. Okt 20:58:05 CET 2020 | So 25. Okt 21:00:44 CET 2020
> elfring@Sonne:~/Projekte/Linux/next-patched> git checkout optimise_disjunction_in_eno.cocci-1 && XX=$(date) && time spatch -D patch --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno3.diff 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno3-errors.txt; YY=$(date) && echo "$XX | $YY"
> …
> real	2m46,097s
> user	10m15,467s
> sys	0m3,984s
> So 25. Okt 21:00:56 CET 2020 | So 25. Okt 21:03:42 CET 2020
> elfring@Sonne:~/Projekte/Linux/next-patched> git checkout optimise_disjunction_in_eno.cocci-1 && XX=$(date) && time spatch -D context --timeout 9 --jobs 4 --chunksize 1 --include-headers --no-includes --dir . scripts/coccinelle/null/eno.cocci > ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno4.txt 2> ~/Projekte/Bau/Linux/scripts/Coccinelle/call_checks/20201023/eno4-errors.txt; YY=$(date) && echo "$XX | $YY"
> …
> real	2m41,472s
> user	9m37,492s
> sys	0m3,834s

In the patch case, the user and system time are essentially identical.  In
the context case, the difference in user time is 2 seconds out of 9.5
minutes, 0.3%.

In the patch case, the real time is a bit slower.  But I believe that this
is due to the time to read in the data from the file system.  I also had a
number like that, but the difference disappeared when I reran it
afterwards, which meant running that case in the same conditions as the
others.

In the context case, the real time is slightly slower with your patch.

So I see no compelling evidence for making the change.

julia

> So 25. Okt 21:03:56 CET 2020 | So 25. Okt 21:06:37 CET 2020
>
>
> > Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz
>
> AMD Phenom(tm) II X4 850 Processor
>
> Will any other aspects become relevant?
>
> Regards,
> Markus
>

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Re: [Cocci] Coccinelle: null: Optimise disjunctions in SmPL script “eno.cocci”

[Markus Elfring]

> In the patch case, the user and system time are essentially identical.
> In the context case, the difference in user time is 2 seconds out of 9.5
> minutes, 0.3%.

This was just a single test run example.


> In the patch case, the real time is a bit slower.

I wonder about such an interpretation.


> But I believe that this is due to the time to read in the data from the file system.

I assume that I could reduce such an influence a bit if I would put
(my) Linux repository into a RAM disk.


> I also had a number like that, but the difference disappeared
> when I reran it afterwards, which meant running that case in the same conditions
> as the others.
>
> In the context case, the real time is slightly slower with your patch.

I guess that the small variations from such a test approach can eventually become
more interesting.


> So I see no compelling evidence for making the change.

This can be.

Should any other differences become more significant?

Regards,
Markus
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