From: Jesper Juhl <juhl-lkml@dif.dk>
To: "Paul `Rusty' Russell" <rusty@rustcorp.com.au>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH] micro optimization in kernel/params.c; don't call to_module_kobject before we really have to.
Date: Sun, 30 Jan 2005 00:45:38 +0100 (CET) [thread overview]
Message-ID: <Pine.LNX.4.62.0501300024110.2829@dragon.hygekrogen.localhost> (raw)
In kernel/params.c::module_attr_show and
kernel/params.c::module_attr_store we call to_module_kobject() and save
the result in a local variable right before a conditional statement that
does not depend on the call to to_module_kobject() and may cause the
function to return. If the function returns before we use the result of
to_module_kobject() then the call is just a waste of time.
The patch moves the call to to_module_kobject() down just before it is
actually used, thus we save a call to the function in a few cases. I doubt
this is in any way measurable, but I see no reason to not move the call -
it should be an infinitesimal improvement with no ill sideeffects.
Please consider applying.
Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
diff -up linux-2.6.11-rc2-bk7-orig/kernel/params.c linux-2.6.11-rc2-bk7/kernel/params.c
--- linux-2.6.11-rc2-bk7-orig/kernel/params.c 2005-01-29 23:54:53.000000000 +0100
+++ linux-2.6.11-rc2-bk7/kernel/params.c 2005-01-30 00:27:08.000000000 +0100
@@ -625,11 +625,12 @@ static ssize_t module_attr_show(struct k
int ret;
attribute = to_module_attr(attr);
- mk = to_module_kobject(kobj);
if (!attribute->show)
return -EPERM;
+ mk = to_module_kobject(kobj);
+
if (!try_module_get(mk->mod))
return -ENODEV;
@@ -649,11 +650,12 @@ static ssize_t module_attr_store(struct
int ret;
attribute = to_module_attr(attr);
- mk = to_module_kobject(kobj);
if (!attribute->store)
return -EPERM;
+ mk = to_module_kobject(kobj);
+
if (!try_module_get(mk->mod))
return -ENODEV;
next reply other threads:[~2005-01-29 23:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-29 23:45 Jesper Juhl [this message]
2005-01-30 0:13 ` [PATCH] micro optimization in kernel/params.c; don't call to_module_kobject before we really have to Brian Gerst
2005-01-30 12:43 ` Jesper Juhl
2005-01-31 3:43 ` Rusty Russell
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