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[Qemu-devel] [PATCH 1/4] rcutorture: remove synchronize_rcu from readers
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 1/4] rcutorture: remove synchronize_rcu from readers |
Date: |
Fri, 9 Mar 2018 14:29:19 +0100 |
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: Paolo Bonzini <address@hidden>
---
tests/rcutorture.c | 4 ----
1 file changed, 4 deletion(-)
diff --git a/tests/rcutorture.c b/tests/rcutorture.c
index 4002ecf123..2a7201549a 100644
--- a/tests/rcutorture.c
+++ b/tests/rcutorture.c
@@ -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 +269,6 @@ 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;
--
2.14.3
- [Qemu-devel] [PATCH 0/4] Optionally use membarrier system call for RCU, Paolo Bonzini, 2018/03/09
- [Qemu-devel] [PATCH 4/4] membarrier: add --enable-membarrier, Paolo Bonzini, 2018/03/09
- [Qemu-devel] [PATCH 2/4] rcu: make memory barriers more explicit, Paolo Bonzini, 2018/03/09
- [Qemu-devel] [PATCH 3/4] membarrier: introduce qemu/sys_membarrier.h, Paolo Bonzini, 2018/03/09
- [Qemu-devel] [PATCH 1/4] rcutorture: remove synchronize_rcu from readers,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 0/4] Optionally use membarrier system call for RCU, no-reply, 2018/03/09
- Re: [Qemu-devel] [PATCH 0/4] Optionally use membarrier system call for RCU, Emilio G. Cota, 2018/03/21