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+The Ultra Kernel Samepage Merging feature
+----------------------------------------------
+/*
+ * Ultra KSM. Copyright (C) 2011-2012 Nai Xia
+ *
+ * This is an improvement upon KSM. Some basic data structures and routines
+ * are borrowed from ksm.c .
+ *
+ * Its new features:
+ * 1. Full system scan:
+ * It automatically scans all user processes' anonymous VMAs. Kernel-user
+ * interaction to submit a memory area to KSM is no longer needed.
+ *
+ * 2. Rich area detection:
+ * It automatically detects rich areas containing abundant duplicated
+ * pages based. Rich areas are given a full scan speed. Poor areas are
+ * sampled at a reasonable speed with very low CPU consumption.
+ *
+ * 3. Ultra Per-page scan speed improvement:
+ * A new hash algorithm is proposed. As a result, on a machine with
+ * Core(TM)2 Quad Q9300 CPU in 32-bit mode and 800MHZ DDR2 main memory, it
+ * can scan memory areas that does not contain duplicated pages at speed of
+ * 627MB/sec ~ 2445MB/sec and can merge duplicated areas at speed of
+ * 477MB/sec ~ 923MB/sec.
+ *
+ * 4. Thrashing area avoidance:
+ * Thrashing area(an VMA that has frequent Ksm page break-out) can be
+ * filtered out. My benchmark shows it's more efficient than KSM's per-page
+ * hash value based volatile page detection.
+ *
+ *
+ * 5. Misc changes upon KSM:
+ * * It has a fully x86-opitmized memcmp dedicated for 4-byte-aligned page
+ * comparison. It's much faster than default C version on x86.
+ * * rmap_item now has an struct *page member to loosely cache a
+ * address-->page mapping, which reduces too much time-costly
+ * follow_page().
+ * * The VMA creation/exit procedures are hooked to let the Ultra KSM know.
+ * * try_to_merge_two_pages() now can revert a pte if it fails. No break_
+ * ksm is needed for this case.
+ *
+ * 6. Full Zero Page consideration(contributed by Figo Zhang)
+ * Now uksmd consider full zero pages as special pages and merge them to an
+ * special unswappable uksm zero page.
+ */
+
+ChangeLog:
+
+2012-05-05 The creation of this Doc
+2012-05-08 UKSM 0.1.1.1 libc crash bug fix, api clean up, doc clean up.
+2012-05-28 UKSM 0.1.1.2 bug fix release
+2012-06-26 UKSM 0.1.2-beta1 first beta release for 0.1.2
+2012-07-2 UKSM 0.1.2-beta2
+2012-07-10 UKSM 0.1.2-beta3
+2012-07-26 UKSM 0.1.2 Fine grained speed control, more scan optimization.
+2012-10-13 UKSM 0.1.2.1 Bug fixes.
+2012-12-31 UKSM 0.1.2.2 Minor bug fixes.
+2014-07-02 UKSM 0.1.2.3 Fix a " __this_cpu_read() in preemptible bug".
+2015-04-22 UKSM 0.1.2.4 Fix a race condition that can sometimes trigger anonying warnings.
+2016-09-10 UKSM 0.1.2.5 Fix a bug in dedup ratio calculation.