• Vineet Gupta's avatar
    ARC: mm: remove __ARCH_USE_5LEVEL_HACK · 6aae3425
    Vineet Gupta authored
    Patch series "elide extraneous generated code for folded p4d/pud/pmd", v3.
    
    This series came out of seemingly benign excursion into
    understanding/removing __ARCH_USE_5LEVEL_HACK from ARC port showing some
    extraneous code being generated despite folded p4d/pud/pmd
    
    | bloat-o-meter2 vmlinux-[AB]*
    | add/remove: 0/0 grow/shrink: 3/0 up/down: 130/0 (130)
    | function                                     old     new   delta
    | free_pgd_range                               548     660    +112
    | p4d_clear_bad                                  2      20     +18
    
    The patches here address that
    
    | bloat-o-meter2 vmlinux-[BF]*
    | add/remove: 0/2 grow/shrink: 0/1 up/down: 0/-386 (-386)
    | function                                     old     new   delta
    | pud_clear_bad                                 20       -     -20
    | p4d_clear_bad                                 20       -     -20
    | free_pgd_range                               660     314    -346
    
    The code savings are not a whole lot, but still worthwhile IMHO.
    
    This patch (of 5):
    
    With paging code made 5-level compliant, this is no longer needed.  ARC
    has software page walker with 2 lookup levels (pgd -> pte)
    
    This was expected to be non functional change but ended with slight
    code bloat due to needless inclusions of p*d_free_tlb() macros which
    will be addressed in further patches.
    
    | bloat-o-meter2 vmlinux-[AB]*
    | add/remove: 0/0 grow/shrink: 2/0 up/down: 128/0 (128)
    | function                                     old     new   delta
    | free_pgd_range                               546     656    +110
    | p4d_clear_bad                                  2      20     +18
    | Total: Before=4137148, After=4137276, chg 0.000000%
    
    Link: http://lkml.kernel.org/r/20191016162400.14796-2-vgupta@synopsys.comSigned-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
    Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Nick Piggin <npiggin@gmail.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Will Deacon <will@kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    6aae3425
pgtable.h 13.8 KB