Commit b9b75817 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

rcutorture: remove synchronize_rcu from readers 



This gives much worse numbers for readers, especially if synchronize_rcu
is made more expensive as is the case with --enable-membarrier.  Before:

   $ tests/rcutorture 10 stress 10
   n_reads: 98304  n_updates: 529  n_mberror: 0
   rcu_stress_count: 98302 2 0 0 0 0 0 0 0 0 0

After:

   $ tests/rcutorture 10 stress 10
   n_reads: 165158482  n_updates: 429  n_mberror: 0
   rcu_stress_count: 165154364 4118 0 0 0 0 0 0 0 0 0

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 148b2ba1

tests/rcutorture.c

+0 −4
Original line number Diff line number Diff line
@@ -238,7 +238,6 @@ long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1]; 
static void *rcu_read_stress_test(void *arg)

{

    int i;

    int itercnt = 0;

    struct rcu_stress *p;

    int pc;

    long long n_reads_local = 0;
@@ -269,9 +268,6 @@ static void *rcu_read_stress_test(void *arg) 
        }

        rcu_stress_local[pc]++;

        n_reads_local++;

        if ((++itercnt % 0x1000) == 0) {

            synchronize_rcu();

        }

    }

    qemu_mutex_lock(&counts_mutex);

    n_reads += n_reads_local;