Re: [RFC 0/2] Delay initializing of large sections of memory

From: Nathan Zimmer
Date: Fri Jun 21 2013 - 16:05:29 EST

On 06/21/2013 12:28 PM, H. Peter Anvin wrote:
On 06/21/2013 10:18 AM, Nathan Zimmer wrote:
Since you made it a compile time option, it would be good to know how
much code it adds, but otherwise I agree with Greg here... this really
shouldn't need to be an option. It *especially* shouldn't need to be a
hand-set runtime option (which looks quite complex, to boot.)
The patchset as a whole is just over 400 lines so it doesn't add alot.
If I were to pull the .config option it would probably remove 30 lines.
I'm more concerned about bytes of code.
Oh, The difference is just under 32k.
371843425 Jun 21 14:08 vmlinux.o /* DELAY_MEM_INIT is not set */
371875600 Jun 21 14:36 vmlinux.o /* DELAY_MEM_INIT=y */

The command line option is too complex but some of the data I haven't
found a way to get at runtime yet.
I think that is probably key.

I suspect the cutoff for this should be a lot lower than 8 TB even, more
like 128 GB or so. The only concern is to not set the cutoff so low
that we can end up running out of memory or with suboptimal NUMA
placement just because of this.
Even at lower amounts of ram there is an positive impact.I it knocks
time off
boot even at as small as a 1TB of ram.
I am not surprised.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at