In message <3EA0D524.7010309@pobox.com> you write:
> Since the kernel does its own string ops, the compiler does not have
> enough information to deduce that further optimization is possible.
You're right, I was measuring without the kernel string ops.
> > Case in point: gcc-3.2 on -O2 on Intel is one instruction longer for
> > your version.
>
> And? It's still slower.
Who gives a flying fuck? You're doing an allocation in there
ferchissakes. Choose the simplest option. Jeff, if you have time to
post on this, I think you need a hobby 8)
char *__constant_kstrdup(const char *s, unsigned int size, int gfp)
{
char *buf = kmalloc(size, gfp);
if (likely(buf))
memcpy(buf, s, size);
return buf;
}
char *__kstrdup(const char *s, int gfp)
{
return __constant_kstrdup(s, strlen(s)+1, gfp);
}
#define kstrdup(str, gfp) \
(__builtin_constant_p(str) && sizeof(str) != sizeof(char *) ? \
__constant_kstrdup(str, sizeof(str), gfp) \
: __kstrdup(str, gfp))
Feature list:
1) Optimizes the constant kstrdup case,
2) Doesn't multi-evaluate args (except if constant string),
3) Uses likely() to bias against the case of kmalloc failing.
OK, so I guess I need a hobby, too..
Rusty.
-- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Wed Apr 23 2003 - 22:00:25 EST