|| ||Ingo Molnar <mingo-AT-elte.hu>|
|| ||Nick Piggin <nickpiggin-AT-yahoo.com.au>|
|| ||Re: [patch 00/14] remap_file_pages protection support|
|| ||Tue, 2 May 2006 13:24:09 +0200|
|| ||blaisorblade-AT-yahoo.it, Andrew Morton <akpm-AT-osdl.org>,
Linux Memory Management <linux-mm-AT-kvack.org>|
* Nick Piggin <email@example.com> wrote:
> >Let's try get back to the good old days when people actually reported
> >their bugs (togther will *real* numbers) to the mailing lists. That way,
> >everybody gets to think about and discuss the problem.
> Speaking of which, let's see some numbers for UML -- performance and
> memory. I don't doubt your claims, but I (and others) would be
> interested to see.
firstly, thanks for the review feedback!
originally i tested this feature with some minimal amount of RAM
simulated by UML 128MB or so. That's just 32 thousand pages, but still
the improvement was massive: context-switch times in UML were cut in
half or more. Process-creation times improved 10-fold. With this feature
included I accidentally (for the first time ever!) confused an UML shell
prompt with a real shell prompt. (before that UML was so slow [even in
"skas mode"] that you'd immediately notice it by the shell's behavior)
the 'have 1 vma instead of 32,000 vmas' thing is a really, really big
plus. It makes UML comparable to Xen, in rough terms of basic VM design.
Now imagine a somewhat larger setup - 16 GB RAM UML instance with 4
million vmas per UML process ... Frankly, without
sys_remap_file_pages_prot() the UML design is still somewhat of a toy.
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