Em Wed, Mar 23, 2011 at 07:29:39PM +0100, Frederic Weisbecker escreveu: > The maximum kilobytes of locked memory that an unprivileged user can > reserve is of 512 kB = 128 pages by default, scaled to the number of > onlined CPUs, which fits well with the tools that use 128 data pages > by default. > > However tools actually use 129 pages, because they need one more for > the user control page. Thus the default mlock threshold is not > sufficient for the default tools needs and we always end up to > evaluate the constant mlock rlimit policy, which doesn't have this > scaling with the number of online CPUs. > > Hence, on systems that have more than 16 CPUs, we overlap the rlimit > threshold and fail to mmap: > > $ perf record ls > Error: failed to mmap with 1 (Operation not permitted) > > Just increase the max unprivileged mlock threshold by one page so > that it supports well perf tools even after 16 CPUs.
Thanks! Acked-by: Arnaldo Carvalho de Melo <[email protected]> > Reported-by: Han Pingtian <[email protected]> > Reported-by: Peter Zijlstra <[email protected]> > Reported-by: Arnaldo Carvalho de Melo <[email protected]> > Signed-off-by: Frederic Weisbecker <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Stephane Eranian <[email protected]> > Cc: Stable <[email protected]> > --- > kernel/perf_event.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/kernel/perf_event.c b/kernel/perf_event.c > index 3472bb1..d5943b0 100644 > --- a/kernel/perf_event.c > +++ b/kernel/perf_event.c > @@ -145,7 +145,8 @@ static struct srcu_struct pmus_srcu; > */ > int sysctl_perf_event_paranoid __read_mostly = 1; > > -int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */ > +/* Minimum for 128 pages + 1 for the user control page */ > +int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */ > > /* > * max perf event sample rate > -- > 1.7.3.2 _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
