On 5/15/13 9:53 AM, Petr Tesarik wrote:
On Wed, 15 May 2013 14:17:39 +0200 Takashi Iwai <tiwai@suse.de> wrote:
At Wed, 15 May 2013 13:39:48 +0200, Petr Tesarik wrote:
[1 <text/plain; US-ASCII (quoted-printable)>] On Tue, 07 May 2013 09:42:03 -0400 Jeff Mahoney <jeffm@suse.com> wrote:
On 5/7/13 9:34 AM, Oliver Neukum wrote:
On Tuesday 07 May 2013 15:28:03 Takashi Iwai wrote:
The original question was about the built-in drivers. These are impossible to avoid to load unless you rebuild the kernel by yourself. Meanwhile, the modules that always loaded are the problem of the user-space stuff. So, we shouldn't mix them up.
But if we always load them we waste about half a page per module on average, which we could conserve if we compile them in.
[...] The concern over wasting sub-page sized chunks of module memory is overblown. In the days where 4 MB RAM was the norm, sure, there's an argument to be made. Now, when people buy systems off the shelves where 4 GB is a "small" system, it's much less of a concern. Now that several tens of kB is caching for like 10 more inodes or something.
Hi Jeff,
there's one use case of the kernel that you haven't considered - using it a secondary kernel for kdump. Now, I still think that a few extra pages is not an issue compared to dozens of megabytes that you need at a minimum for the crash kernel (and hundreds of megabytes you need on some machines), but keeping the kernel small is still an important target.
It's other way round. For kdump, you'll likely save more memory by moving things out of built-in kernel, as kdump initrd doesn't have to load all modules.
I know. And that's why I appreciate Jean's effort. But Jeff's mail sounded like he thinks that gigabytes of RAM are always available to the kernel on any modern hardware. They aren't.
I can see how you'd take that away from my comment. I also mentioned I was only talking about a few tens of kB. It's not worth trying to save that while wasting hundreds building in modules that aren't required everywhere. -Jeff -- Jeff Mahoney SUSE Labs