Re: [PATCH] ext3_clear_inode(): avoid kfree(NULL)

From: Nick Piggin
Date: Sat Jun 24 2006 - 12:15:24 EST


Arjan van de Ven wrote:
The jne is expected to fail, so we will always continue to 0x13. Now is
this a problem with x86/x86_64?


I'm not saying there is a problem; likely/unlikely do have an effect for
sure, it's just not a "make it free" thing....

On x86 I think the main saving is the icache one. However I guess
gcc would try to align with the branch prediction behaviour for
unknown branches too.

The microoptimisation is that the call avoids the unlikely branch
in kfree. Maybe for x86 this isn't going to matter, but for some
architectures in might.

--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com -
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/