2021-10-05 07:02:13

by Mark-PK Tsai (蔡沛剛)

Subject: [PATCH] clk: make clk_core_lookup faster by using clk name hash

Compare hash value before strcmp the full name to make
clk_core_lookup faster.

It make clk driver probe 30 percent faster on the platform
have 1483 registered clks and average clock name length 20.

Signed-off-by: Mark-PK Tsai <[email protected]>
---
drivers/clk/clk.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 65508eb89ec9..d5f65fda3db8 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -89,6 +89,7 @@ struct clk_core {
struct hlist_node debug_node;
#endif
struct kref ref;
+ unsigned int hash;
};

#define CREATE_TRACE_POINTS
@@ -292,16 +293,17 @@ struct clk_hw *clk_hw_get_parent(const struct clk_hw *hw)
EXPORT_SYMBOL_GPL(clk_hw_get_parent);

static struct clk_core *__clk_lookup_subtree(const char *name,
+ unsigned int hash,
struct clk_core *core)
{
struct clk_core *child;
struct clk_core *ret;

- if (!strcmp(core->name, name))
+ if (hash == core->hash && !strcmp(core->name, name))
return core;

hlist_for_each_entry(child, &core->children, child_node) {
- ret = __clk_lookup_subtree(name, child);
+ ret = __clk_lookup_subtree(name, hash, child);
if (ret)
return ret;
}
@@ -313,20 +315,22 @@ static struct clk_core *clk_core_lookup(const char *name)
{
struct clk_core *root_clk;
struct clk_core *ret;
+ unsigned int hash;

if (!name)
return NULL;

+ hash = full_name_hash(NULL, name, strlen(name));
/* search the 'proper' clk tree first */
hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
- ret = __clk_lookup_subtree(name, root_clk);
+ ret = __clk_lookup_subtree(name, hash, root_clk);
if (ret)
return ret;
}

/* if not found, then search the orphan tree */
hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
- ret = __clk_lookup_subtree(name, root_clk);
+ ret = __clk_lookup_subtree(name, hash, root_clk);
if (ret)
return ret;
}
@@ -3827,6 +3831,7 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
goto fail_name;
}

+ core->hash = full_name_hash(NULL, core->name, strlen(core->name));
if (WARN_ON(!init->ops)) {
ret = -EINVAL;
goto fail_ops;
--
2.18.0

2021-10-15 07:51:42

by Stephen Boyd

Subject: Re: [PATCH] clk: make clk_core_lookup faster by using clk name hash

Quoting Mark-PK Tsai (2021-10-04 23:59:49)
> Compare hash value before strcmp the full name to make
> clk_core_lookup faster.
>
> It make clk driver probe 30 percent faster on the platform
> have 1483 registered clks and average clock name length 20.

Why is clk_core_lookup() a fast path for you?

2021-10-18 03:49:57

by Chen-Yu Tsai

Subject: Re: [PATCH] clk: make clk_core_lookup faster by using clk name hash

On Fri, Oct 15, 2021 at 8:44 AM Stephen Boyd <[email protected]> wrote:
>
> Quoting Mark-PK Tsai (2021-10-04 23:59:49)
> > Compare hash value before strcmp the full name to make
> > clk_core_lookup faster.
> >
> > It make clk driver probe 30 percent faster on the platform
> > have 1483 registered clks and average clock name length 20.
>
> Why is clk_core_lookup() a fast path for you?

Maybe because the Mediatek clock driver still does global clk name matching
to resolve parents?