Andrew, it turns out that your idea of kzalloc_gfp_kernel() does save
a bit. Here's a patch that shouldn't even make Linus look for a
cattle prod.
[BTW, it's rather amusing watching ld use a gig of memory and several
minutes of CPU time as it strains to link an allyesconfig kernel]
- R.
Here's a patch to get the effect of having kzalloc_gfp_kernel()
without affecting any callers. It makes kzalloc() an inline that just
calls __kzalloc_gfp_kernel() if the flags parameter is a compile-time
constant and is GFP_KERNEL, and calls __kzalloc() otherwise.
On an x86_64 allyesconfig kernel, I see the following size:
text data bss dec hex filename
24202272 7609162 1998512 33809946 203e61a ../kbuild-before/vmlinux
24201601 7609266 1998512 33809379 203e3e3 ../kbuild-after/vmlinux
for a net savings of 671 bytes of text (at a cost of 104 bytes of data
for some reason). As use of kzalloc() becomes more widespread, this
should get even better.
Signed-off-by: Roland Dreier <[email protected]>
diff --git a/include/linux/slab.h b/include/linux/slab.h
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -99,7 +99,16 @@ found:
return __kmalloc(size, flags);
}
-extern void *kzalloc(size_t, unsigned int __nocast);
+extern void *__kzalloc(size_t, unsigned int __nocast);
+extern void *__kzalloc_gfp_kernel(size_t);
+
+static inline void *kzalloc(size_t size, unsigned int __nocast flags)
+{
+ if (__builtin_constant_p(flags) && flags == GFP_KERNEL)
+ return __kzalloc_gfp_kernel(size);
+ else
+ return __kzalloc(size, flags);
+}
/**
* kcalloc - allocate memory for an array. The memory is set to zero.
diff --git a/mm/slab.c b/mm/slab.c
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2985,14 +2985,20 @@ EXPORT_SYMBOL(kmem_cache_free);
* @size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*/
-void *kzalloc(size_t size, unsigned int __nocast flags)
+void *__kzalloc(size_t size, unsigned int __nocast flags)
{
void *ret = kmalloc(size, flags);
if (ret)
memset(ret, 0, size);
return ret;
}
-EXPORT_SYMBOL(kzalloc);
+EXPORT_SYMBOL(__kzalloc);
+
+void *__kzalloc_gfp_kernel(size_t size)
+{
+ return __kzalloc(size, GFP_KERNEL);
+}
+EXPORT_SYMBOL(__kzalloc_gfp_kernel);
/**
* kfree - free previously allocated memory
-
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