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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-26 04:42:12 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-26 05:27:59 -0300
commita156245300d5362a3b4c4afdace9e2b90169fe43 (patch)
tree392741d5ee3e05bc089c7af2db884b99899217d7 /Documentation/vm/uksm.txt
parent03dd4cb26d967f9588437b0fc9cc0e8353322bb7 (diff)
Remove UKSM support since the latest patch is very unstable and obsolete for the 4.5-gnu kernel version
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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.