• Ingo Molnar's avatar
    perf bench: Remove the prefaulting complication from 'perf bench mem mem*' · 6db175c7
    Ingo Molnar authored
    So 'perf bench mem memcpy/memset' has elaborate code to measure
    memcpy()/memset() performance both with freshly allocated buffers (which
    includes initial page fault overhead) and with preallocated buffers.
    
    But the thing is, the resulting bandwidth results are mostly
    meaningless, because page faults dominate so much of the cost.
    
    It might make sense to measure cache cold vs. cache hot performance, but
    the code does not do this.
    
    So remove this complication, and always prefault the ranges before using
    them.
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/1445241870-24854-6-git-send-email-mingo@kernel.org
    [ Remove --no-prefault, --only-prefault from docs, noticed by David Ahern ]
    Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    6db175c7
mem-functions.c 8.44 KB