* [Cocci] Performance issue with quite simple patch?
@ 2021-01-13 9:48 Maxime Ripard
2021-01-13 10:58 ` Julia Lawall
0 siblings, 1 reply; 3+ messages in thread
From: Maxime Ripard @ 2021-01-13 9:48 UTC (permalink / raw)
To: cocci
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Hi!
I've been trying to get a patch to rename any variable called "state" in
a given set of callbacks.
This is the patch that I've come up with:
@ plane_atomic_func @
identifier helpers;
identifier func;
@@
(
static const struct drm_plane_helper_funcs helpers = {
...,
.atomic_check = func,
...,
};
|
static const struct drm_plane_helper_funcs helpers = {
...,
.atomic_disable = func,
...,
};
|
static const struct drm_plane_helper_funcs helpers = {
...,
.atomic_update = func,
...,
};
)
@@
identifier plane_atomic_func.func;
symbol state;
expression e;
type T;
@@
func(...)
{
...
- T state = e;
+ T plane_state = e;
<+...
- state
+ plane_state
...+>
}
However, it seems like at least on a file (in Linux,
drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c), it takes quite big
performance hit with one CPU running at 100% until the timeout is hit.
Replacing <+... by ... makes it work instantly, but doesn't really do
what I'm expecting, so I guess it's a matter of the patch being
subobtimal?
Is there a more optimal way of doing it?
Thanks!
Maxime
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [Cocci] Performance issue with quite simple patch? 2021-01-13 9:48 [Cocci] Performance issue with quite simple patch? Maxime Ripard @ 2021-01-13 10:58 ` Julia Lawall 2021-01-14 13:24 ` Maxime Ripard 0 siblings, 1 reply; 3+ messages in thread From: Julia Lawall @ 2021-01-13 10:58 UTC (permalink / raw) To: Maxime Ripard; +Cc: cocci On Wed, 13 Jan 2021, Maxime Ripard wrote: > Hi! > > I've been trying to get a patch to rename any variable called "state" in > a given set of callbacks. > > This is the patch that I've come up with: > > @ plane_atomic_func @ > identifier helpers; > identifier func; > @@ > > ( > static const struct drm_plane_helper_funcs helpers = { > ..., > .atomic_check = func, > ..., > }; > | > static const struct drm_plane_helper_funcs helpers = { > ..., > .atomic_disable = func, > ..., > }; > | > static const struct drm_plane_helper_funcs helpers = { > ..., > .atomic_update = func, > ..., > }; > ) You don't need the ...s in the above. For structure declarations Coccinelle is happy as long as what you specify is a subset of what is present. The static and const aren't essential either. If you remove them, the pattern will match whethe thy are present or not. > > @@ > identifier plane_atomic_func.func; > symbol state; > expression e; > type T; > @@ > > func(...) > { > ... > - T state = e; > + T plane_state = e; > <+... > - state > + plane_state > ...+> > } > > However, it seems like at least on a file (in Linux, > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c), it takes quite big > performance hit with one CPU running at 100% until the timeout is hit. > > Replacing <+... by ... makes it work instantly, but doesn't really do > what I'm expecting, so I guess it's a matter of the patch being > subobtimal? > > Is there a more optimal way of doing it? In your rule, I donkt think that there is really any essential connection between the declaration and the use? You just want to change state to plane_state when it occurs in one of the functions that you detected. So you could at least try the following and see if it gives any false positives: @@ identifier plane_atomic_func.func; symbol state; expression e; type T; @@ func(...) { <... ( - T state = e; + T plane_state = e; | - state + plane_state ) ...> } _______________________________________________ Cocci mailing list Cocci@systeme.lip6.fr https://systeme.lip6.fr/mailman/listinfo/cocci ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Cocci] Performance issue with quite simple patch? 2021-01-13 10:58 ` Julia Lawall @ 2021-01-14 13:24 ` Maxime Ripard 0 siblings, 0 replies; 3+ messages in thread From: Maxime Ripard @ 2021-01-14 13:24 UTC (permalink / raw) To: Julia Lawall; +Cc: cocci [-- Attachment #1.1: Type: text/plain, Size: 3374 bytes --] Hi Julia, On Wed, Jan 13, 2021 at 11:58:41AM +0100, Julia Lawall wrote: > On Wed, 13 Jan 2021, Maxime Ripard wrote: > > > Hi! > > > > I've been trying to get a patch to rename any variable called "state" in > > a given set of callbacks. > > > > This is the patch that I've come up with: > > > > @ plane_atomic_func @ > > identifier helpers; > > identifier func; > > @@ > > > > ( > > static const struct drm_plane_helper_funcs helpers = { > > ..., > > .atomic_check = func, > > ..., > > }; > > | > > static const struct drm_plane_helper_funcs helpers = { > > ..., > > .atomic_disable = func, > > ..., > > }; > > | > > static const struct drm_plane_helper_funcs helpers = { > > ..., > > .atomic_update = func, > > ..., > > }; > > ) > > You don't need the ...s in the above. For structure declarations > Coccinelle is happy as long as what you specify is a subset of what is > present. The static and const aren't essential either. If you remove > them, the pattern will match whethe thy are present or not. Oh, that's good to know, thanks! > > > > @@ > > identifier plane_atomic_func.func; > > symbol state; > > expression e; > > type T; > > @@ > > > > func(...) > > { > > ... > > - T state = e; > > + T plane_state = e; > > <+... > > - state > > + plane_state > > ...+> > > } > > > > However, it seems like at least on a file (in Linux, > > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c), it takes quite big > > performance hit with one CPU running at 100% until the timeout is hit. > > > > Replacing <+... by ... makes it work instantly, but doesn't really do > > what I'm expecting, so I guess it's a matter of the patch being > > subobtimal? > > > > Is there a more optimal way of doing it? > > In your rule, I donkt think that there is really any essential connection > between the declaration and the use? You just want to change state to > plane_state when it occurs in one of the functions that you detected. I'm sorry, I forgot to mention that I only want the change to occur if it's a variable declared in the function, not an argument to it > So you could at least try the following and see if it gives any false positives: > > @@ > identifier plane_atomic_func.func; > symbol state; > expression e; > type T; > @@ > > func(...) > { > <... > ( > - T state = e; > + T plane_state = e; > | > - state > + plane_state > ) > ...> > } I would never have thought of that, thanks :) I tried to adjust it to match only on functions that have such a variable defined: @ plane_atomic_func @ identifier helpers; identifier func; @@ struct drm_plane_helper_funcs helpers = { .atomic_check = func, }; @ has_variable_state @ identifier plane_atomic_func.func; symbol state; expression e; type T; @@ func(...) { ... T state = e; ... } @ depends on has_variable_state @ identifier plane_atomic_func.func; symbol state; expression e; type T; @@ func(...) { <... ( - T state = e; + T plane_state = e; | - state + plane_state ) ...> } But it's still choking on that same file (drivers/gpu/drm//atmel-hlcdc/atmel_hlcdc_plane.c). Every other file that matches takes at most a few seconds though, so it seems a bit weird Maxime [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 228 bytes --] [-- Attachment #2: Type: text/plain, Size: 136 bytes --] _______________________________________________ Cocci mailing list Cocci@systeme.lip6.fr https://systeme.lip6.fr/mailman/listinfo/cocci ^ permalink raw reply [flat|nested] 3+ messages in thread
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