1. 17 Jan, 2018 36 commits
  2. 10 Jan, 2018 4 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.4.111 · c5ae3a6a
      Greg Kroah-Hartman authored
      c5ae3a6a
    • Greg Kroah-Hartman's avatar
      Fix build error in vma.c · 516fa79e
      Greg Kroah-Hartman authored
      This fixes the following much-reported build issue:
      
      arch/x86/entry/vdso/vma.c: In function ‘map_vdso’:
      arch/x86/entry/vdso/vma.c:175:9: error:
              implicit declaration of function ‘pvclock_pvti_cpu0_va’
      
      on some arches and configurations.
      
      Thanks to Guenter for being persistent enough to get it fixed :)
      Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      516fa79e
    • Borislav Petkov's avatar
      Map the vsyscall page with _PAGE_USER · 6dcf5491
      Borislav Petkov authored
      This needs to happen early in kaiser_pagetable_walk(), before the
      hierarchy is established so that _PAGE_USER permission can be really
      set.
      
      A proper fix would be to teach kaiser_pagetable_walk() to update those
      permissions but the vsyscall page is the only exception here so ...
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Acked-by: default avatarHugh Dickins <hughd@google.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      6dcf5491
    • Alexey Dobriyan's avatar
      proc: much faster /proc/vmstat · 90191f71
      Alexey Dobriyan authored
      commit 68ba0326 upstream.
      
      Every current KDE system has process named ksysguardd polling files
      below once in several seconds:
      
      	$ strace -e trace=open -p $(pidof ksysguardd)
      	Process 1812 attached
      	open("/etc/mtab", O_RDONLY|O_CLOEXEC)   = 8
      	open("/etc/mtab", O_RDONLY|O_CLOEXEC)   = 8
      	open("/proc/net/dev", O_RDONLY)         = 8
      	open("/proc/net/wireless", O_RDONLY)    = -1 ENOENT (No such file or directory)
      	open("/proc/stat", O_RDONLY)            = 8
      	open("/proc/vmstat", O_RDONLY)          = 8
      
      Hell knows what it is doing but speed up reading /proc/vmstat by 33%!
      
      Benchmark is open+read+close 1.000.000 times.
      
      			BEFORE
      $ perf stat -r 10 taskset -c 3 ./proc-vmstat
      
       Performance counter stats for 'taskset -c 3 ./proc-vmstat' (10 runs):
      
            13146.768464      task-clock (msec)         #    0.960 CPUs utilized            ( +-  0.60% )
                      15      context-switches          #    0.001 K/sec                    ( +-  1.41% )
                       1      cpu-migrations            #    0.000 K/sec                    ( +- 11.11% )
                     104      page-faults               #    0.008 K/sec                    ( +-  0.57% )
          45,489,799,349      cycles                    #    3.460 GHz                      ( +-  0.03% )
           9,970,175,743      stalled-cycles-frontend   #   21.92% frontend cycles idle     ( +-  0.10% )
           2,800,298,015      stalled-cycles-backend    #   6.16% backend cycles idle       ( +-  0.32% )
          79,241,190,850      instructions              #    1.74  insn per cycle
                                                        #    0.13  stalled cycles per insn  ( +-  0.00% )
          17,616,096,146      branches                  # 1339.956 M/sec                    ( +-  0.00% )
             176,106,232      branch-misses             #    1.00% of all branches          ( +-  0.18% )
      
            13.691078109 seconds time elapsed                                          ( +-  0.03% )
            ^^^^^^^^^^^^
      
      			AFTER
      $ perf stat -r 10 taskset -c 3 ./proc-vmstat
      
       Performance counter stats for 'taskset -c 3 ./proc-vmstat' (10 runs):
      
             8688.353749      task-clock (msec)         #    0.950 CPUs utilized            ( +-  1.25% )
                      10      context-switches          #    0.001 K/sec                    ( +-  2.13% )
                       1      cpu-migrations            #    0.000 K/sec
                     104      page-faults               #    0.012 K/sec                    ( +-  0.56% )
          30,384,010,730      cycles                    #    3.497 GHz                      ( +-  0.07% )
          12,296,259,407      stalled-cycles-frontend   #   40.47% frontend cycles idle     ( +-  0.13% )
           3,370,668,651      stalled-cycles-backend    #  11.09% backend cycles idle       ( +-  0.69% )
          28,969,052,879      instructions              #    0.95  insn per cycle
                                                        #    0.42  stalled cycles per insn  ( +-  0.01% )
           6,308,245,891      branches                  #  726.058 M/sec                    ( +-  0.00% )
             214,685,502      branch-misses             #    3.40% of all branches          ( +-  0.26% )
      
             9.146081052 seconds time elapsed                                          ( +-  0.07% )
             ^^^^^^^^^^^
      
      vsnprintf() is slow because:
      
      1. format_decode() is busy looking for format specifier: 2 branches
         per character (not in this case, but in others)
      
      2. approximately million branches while parsing format mini language
         and everywhere
      
      3.  just look at what string() does /proc/vmstat is good case because
         most of its content are strings
      
      Link: http://lkml.kernel.org/r/20160806125455.GA1187@p183.telecom.bySigned-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
      Cc: Joe Perches <joe@perches.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      90191f71