• Nick Piggin's avatar
    vmscan: move isolate_lru_page() to vmscan.c · 62695a84
    Nick Piggin authored
    On large memory systems, the VM can spend way too much time scanning
    through pages that it cannot (or should not) evict from memory.  Not only
    does it use up CPU time, but it also provokes lock contention and can
    leave large systems under memory presure in a catatonic state.
    
    This patch series improves VM scalability by:
    
    1) putting filesystem backed, swap backed and unevictable pages
       onto their own LRUs, so the system only scans the pages that it
       can/should evict from memory
    
    2) switching to two handed clock replacement for the anonymous LRUs,
       so the number of pages that need to be scanned when the system
       starts swapping is bound to a reasonable number
    
    3) keeping unevictable pages off the LRU completely, so the
       VM does not waste CPU time scanning them. ramfs, ramdisk,
       SHM_LOCKED shared memory segments and mlock()ed VMA pages
       are keept on the unevictable list.
    
    This patch:
    
    isolate_lru_page logically belongs to be in vmscan.c than migrate.c.
    
    It is tough, because we don't need that function without memory migration
    so there is a valid argument to have it in migrate.c.  However a
    subsequent patch needs to make use of it in the core mm, so we can happily
    move it to vmscan.c.
    
    Also, make the function a little more generic by not requiring that it
    adds an isolated page to a given list.  Callers can do that.
    
    	Note that we now have '__isolate_lru_page()', that does
    	something quite different, visible outside of vmscan.c
    	for use with memory controller.  Methinks we need to
    	rationalize these names/purposes.	--lts
    
    [akpm@linux-foundation.org: fix mm/memory_hotplug.c build]
    Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
    Signed-off-by: default avatarRik van Riel <riel@redhat.com>
    Signed-off-by: default avatarLee Schermerhorn <Lee.Schermerhorn@hp.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    62695a84
migrate.h 1.33 KB