On 08/27/2012 07:48 PM, Borislav Petkov wrote:
On Mon, Aug 27, 2012 at 03:58:59PM +0200, Andi Kleen wrote:
On Mon, Aug 27, 2012 at 04:55:03PM +0530, Naveen N. Rao wrote:
Many MCE boot flags are boolean in nature, but are declared as integers
currently. We can pack these into a bitfield to save some space.
Note that this doesn't necessarily save anything because it needs more
code to access, and accesses are more common than the flag
cmpl $0,foo(%rip) 7 bytes
testl $1,foo(%rip) 10 bytes
I got 7 bytes:
12e9: f6 05 00 00 00 00 02 testb $0x2,0x0(%rip) # 12f0
<mce_start_timer.isra.18+0x30>
vs the old:
1654: 83 3d 00 00 00 00 00 cmpl $0x0,0x0(%rip) # 165b
<mce_start_timer.clone.15+0x37>
also 7 bytes.
I'm seeing the same here. GCC v4.7 with -O2 generates testb and cmpb,
which are both 7 bytes long.
Thanks,
Naveen
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
