tree b727812682ca9f30169496a30a1e51620f53c7c9
parent 912985dce45ef18fcdd9f5439fef054e0e22302a
author Rusty Russell <rusty@rustcorp.com.au> 1218581573 -0500
committer Rusty Russell <rusty@rustcorp.com.au> 1218527573 +1000

lguest: use get_user_pages_fast() instead of get_user_pages()

Using a simple page table thrashing program I measure a slight
improvement.  The program creates five processes.  Each touches 1000
pages then schedules the next process.  We repeat this 1000 times.  As
lguest only caches 4 cr3 values, this rebuilds a lot of shadow page
tables requiring virt->phys mappings.

	Before: 5.93 seconds
	After: 5.40 seconds

(Counts of slow vs fastpath in this usage are 6092 and 2852462 respectively.)

And more importantly for lguest, the code is simpler.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>