[lttng-dev] [PATCH V2] urcu: avoid false sharing for rcu_gp_ctr
Lai Jiangshan
laijs at cn.fujitsu.com
Tue Dec 11 01:28:59 EST 2012
>From 66f50786b9d5f1bcf2ad56e3a9ab905005c6cd90 Mon Sep 17 00:00:00 2001
From: Lai Jiangshan <laijs at cn.fujitsu.com>
Date: Tue, 11 Dec 2012 14:24:44 +0800
Subject: [PATCH] urcu: avoid false sharing for rcu_gp_ctr
@rcu_gp_ctr and @registry share the same cache line, it causes
false sharing and slowdown both of the read site and update site.
Fix: Use different cache line for them.
Although rcu_gp_futex is updated less than rcu_gp_ctr, but
they always be accessed at almost the same time, so we also move rcu_gp_futex
to the cacheline of rcu_gp_ctr to reduce the cacheline-usage or cache-missing
of read site.
test: (4X6=24 CPUs)
Before patch:
[root at localhost userspace-rcu]# ./tests/test_urcu_mb 20 1 20
SUMMARY ./tests/test_urcu_mb testdur 20 nr_readers 20 rdur 0 wdur 0 nr_writers 1 wdelay 0 nr_reads 2100285330 nr_writes 3390219 nr_ops 2103675549
[root at localhost userspace-rcu]# ./tests/test_urcu_mb 20 1 20
SUMMARY ./tests/test_urcu_mb testdur 20 nr_readers 20 rdur 0 wdur 0 nr_writers 1 wdelay 0 nr_reads 1619868562 nr_writes 3529478 nr_ops 1623398040
[root at localhost userspace-rcu]# ./tests/test_urcu_mb 20 1 20
SUMMARY ./tests/test_urcu_mb testdur 20 nr_readers 20 rdur 0 wdur 0 nr_writers 1 wdelay 0 nr_reads 1949067038 nr_writes 3469334 nr_ops 1952536372
after patch:
[root at localhost userspace-rcu]# ./tests/test_urcu_mb 20 1 20
SUMMARY ./tests/test_urcu_mb testdur 20 nr_readers 20 rdur 0 wdur 0 nr_writers 1 wdelay 0 nr_reads 3380191848 nr_writes 4903248 nr_ops 3385095096
[root at localhost userspace-rcu]# ./tests/test_urcu_mb 20 1 20
SUMMARY ./tests/test_urcu_mb testdur 20 nr_readers 20 rdur 0 wdur 0 nr_writers 1 wdelay 0 nr_reads 3397637486 nr_writes 4129809 nr_ops 3401767295
Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
---
Makefile.am | 10 +++++-----
compat_rcu_gp.lds | 25 +++++++++++++++++++++++++
compat_rcu_gp_bp.lds | 24 ++++++++++++++++++++++++
compat_rcu_gp_mb.lds | 25 +++++++++++++++++++++++++
compat_rcu_gp_qsbr.lds | 25 +++++++++++++++++++++++++
compat_rcu_gp_signal.lds | 25 +++++++++++++++++++++++++
urcu-bp.c | 14 ++++----------
urcu-qsbr.c | 35 +++++++++++++++--------------------
urcu.c | 34 +++++++++++++---------------------
urcu/map/urcu-bp.h | 3 +--
urcu/map/urcu-qsbr.h | 3 +--
urcu/map/urcu.h | 9 +++------
urcu/static/urcu-bp.h | 23 ++++++++++++++---------
urcu/static/urcu-qsbr.h | 39 ++++++++++++++++++++++++---------------
urcu/static/urcu.h | 38 ++++++++++++++++++++++++--------------
15 files changed, 228 insertions(+), 104 deletions(-)
create mode 100644 compat_rcu_gp.lds
create mode 100644 compat_rcu_gp_bp.lds
create mode 100644 compat_rcu_gp_mb.lds
create mode 100644 compat_rcu_gp_qsbr.lds
create mode 100644 compat_rcu_gp_signal.lds
diff --git a/Makefile.am b/Makefile.am
index 0a4d357..b2b7b6a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -56,21 +56,21 @@ lib_LTLIBRARIES = liburcu-common.la \
#
liburcu_common_la_SOURCES = wfqueue.c wfcqueue.c wfstack.c $(COMPAT)
-liburcu_la_SOURCES = urcu.c urcu-pointer.c $(COMPAT)
+liburcu_la_SOURCES = urcu.c urcu-pointer.c compat_rcu_gp.lds $(COMPAT)
liburcu_la_LIBADD = liburcu-common.la
-liburcu_qsbr_la_SOURCES = urcu-qsbr.c urcu-pointer.c $(COMPAT)
+liburcu_qsbr_la_SOURCES = urcu-qsbr.c urcu-pointer.c compat_rcu_gp_qsbr.lds $(COMPAT)
liburcu_qsbr_la_LIBADD = liburcu-common.la
-liburcu_mb_la_SOURCES = urcu.c urcu-pointer.c $(COMPAT)
+liburcu_mb_la_SOURCES = urcu.c urcu-pointer.c compat_rcu_gp_mb.lds $(COMPAT)
liburcu_mb_la_CFLAGS = -DRCU_MB
liburcu_mb_la_LIBADD = liburcu-common.la
-liburcu_signal_la_SOURCES = urcu.c urcu-pointer.c $(COMPAT)
+liburcu_signal_la_SOURCES = urcu.c urcu-pointer.c compat_rcu_gp_signal.lds $(COMPAT)
liburcu_signal_la_CFLAGS = -DRCU_SIGNAL
liburcu_signal_la_LIBADD = liburcu-common.la
-liburcu_bp_la_SOURCES = urcu-bp.c urcu-pointer.c $(COMPAT)
+liburcu_bp_la_SOURCES = urcu-bp.c urcu-pointer.c compat_rcu_gp_bp.lds $(COMPAT)
liburcu_bp_la_LIBADD = liburcu-common.la
liburcu_cds_la_SOURCES = rculfqueue.c rculfstack.c lfstack.c \
diff --git a/compat_rcu_gp.lds b/compat_rcu_gp.lds
new file mode 100644
index 0000000..506a4ae
--- /dev/null
+++ b/compat_rcu_gp.lds
@@ -0,0 +1,25 @@
+/*
+ * compat_rcu_gp.lds
+ *
+ * Linker Script for compatibility of liburcu
+ *
+ * Copyright (c) 2012 Lai Jiangshan <laijs at cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+rcu_gp_ctr_memb = rcu_gp_memb;
+rcu_gp_futex_memb = rcu_gp_memb + 8;
+
diff --git a/compat_rcu_gp_bp.lds b/compat_rcu_gp_bp.lds
new file mode 100644
index 0000000..6ab7dfa
--- /dev/null
+++ b/compat_rcu_gp_bp.lds
@@ -0,0 +1,24 @@
+/*
+ * compat_rcu_gp_bp.lds
+ *
+ * Linker Script for compatibility of liburcu-bp
+ *
+ * Copyright (c) 2012 Lai Jiangshan <laijs at cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+rcu_gp_ctr_bp = rcu_gp_bp;
+
diff --git a/compat_rcu_gp_mb.lds b/compat_rcu_gp_mb.lds
new file mode 100644
index 0000000..8313588
--- /dev/null
+++ b/compat_rcu_gp_mb.lds
@@ -0,0 +1,25 @@
+/*
+ * compat_rcu_gp_mb.lds
+ *
+ * Linker Script for compatibility of liburcu-mb
+ *
+ * Copyright (c) 2012 Lai Jiangshan <laijs at cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+rcu_gp_ctr_mb = rcu_gp_mb;
+rcu_gp_futex_mb = rcu_gp_mb + 8;
+
diff --git a/compat_rcu_gp_qsbr.lds b/compat_rcu_gp_qsbr.lds
new file mode 100644
index 0000000..d27e163
--- /dev/null
+++ b/compat_rcu_gp_qsbr.lds
@@ -0,0 +1,25 @@
+/*
+ * compat_rcu_gp_qsbr.lds
+ *
+ * Linker Script for compatibility of liburcu-qsbr
+ *
+ * Copyright (c) 2012 Lai Jiangshan <laijs at cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+rcu_gp_ctr_qsbr = rcu_gp_qsbr;
+rcu_gp_futex_qsbr = rcu_gp_qsbr + 8;
+
diff --git a/compat_rcu_gp_signal.lds b/compat_rcu_gp_signal.lds
new file mode 100644
index 0000000..f0a447d
--- /dev/null
+++ b/compat_rcu_gp_signal.lds
@@ -0,0 +1,25 @@
+/*
+ * compat_rcu_gp_signal.lds
+ *
+ * Linker Script for compatibility of liburcu-signal
+ *
+ * Copyright (c) 2012 Lai Jiangshan <laijs at cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+rcu_gp_ctr_signal = rcu_gp_signal;
+rcu_gp_futex_signal = rcu_gp_signal + 8;
+
diff --git a/urcu-bp.c b/urcu-bp.c
index f99c0e5..2a2455b 100644
--- a/urcu-bp.c
+++ b/urcu-bp.c
@@ -103,6 +103,8 @@ void *mremap_wrapper(void *old_address, size_t old_size,
void __attribute__((destructor)) rcu_bp_exit(void);
static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
+/* Init the ctr as RCU_GP_COUNT, to accelerate the reader fast path. */
+struct urcu_gp rcu_gp = { .ctr = RCU_GP_COUNT };
#ifdef DEBUG_YIELD
unsigned int rcu_yield_active;
@@ -110,14 +112,6 @@ DEFINE_URCU_TLS(unsigned int, rcu_rand_yield);
#endif
/*
- * Global grace period counter.
- * Contains the current RCU_GP_CTR_PHASE.
- * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path.
- * Written to only by writer with mutex taken. Read by both writer and readers.
- */
-unsigned long rcu_gp_ctr = RCU_GP_COUNT;
-
-/*
* Pointer to registry elements. Written to only by each individual reader. Read
* by both the reader and the writers.
*/
@@ -174,7 +168,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
/*
* Wait for each thread URCU_TLS(rcu_reader).ctr to either
* indicate quiescence (not nested), or observe the current
- * rcu_gp_ctr value.
+ * rcu_gp.ctr value.
*/
for (;;) {
wait_loops++;
@@ -250,7 +244,7 @@ void synchronize_rcu(void)
cmm_smp_mb();
/* Switch parity: 0 -> 1, 1 -> 0 */
- CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+ CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR_PHASE);
/*
* Must commit qparity update to memory before waiting for other parity
diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 3c2c65d..5e2510d 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -53,13 +53,8 @@
void __attribute__((destructor)) rcu_exit(void);
static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
-
-int32_t rcu_gp_futex;
-
-/*
- * Global grace period counter.
- */
-unsigned long rcu_gp_ctr = RCU_GP_ONLINE;
+/* Init the ctr as RCU_GP_ONLINE, to accelerate the reader fast path. */
+struct urcu_gp rcu_gp = { { .ctr = RCU_GP_ONLINE } };
/*
* Active attempts to check for reader Q.S. before calling futex().
@@ -118,8 +113,8 @@ static void wait_gp(void)
{
/* Read reader_gp before read futex */
cmm_smp_rmb();
- if (uatomic_read(&rcu_gp_futex) == -1)
- futex_noasync(&rcu_gp_futex, FUTEX_WAIT, -1,
+ if (uatomic_read(&rcu_gp.futex) == -1)
+ futex_noasync(&rcu_gp.futex, FUTEX_WAIT, -1,
NULL, NULL, 0);
}
@@ -133,12 +128,12 @@ static void wait_for_readers(struct cds_list_head *input_readers,
/*
* Wait for each thread URCU_TLS(rcu_reader).ctr to either
* indicate quiescence (offline), or for them to observe the
- * current rcu_gp_ctr value.
+ * current rcu_gp.ctr value.
*/
for (;;) {
wait_loops++;
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
- uatomic_set(&rcu_gp_futex, -1);
+ uatomic_set(&rcu_gp.futex, -1);
/*
* Write futex before write waiting (the other side
* reads them in the opposite order).
@@ -177,7 +172,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
cmm_smp_mb();
- uatomic_set(&rcu_gp_futex, 0);
+ uatomic_set(&rcu_gp.futex, 0);
}
break;
} else {
@@ -253,11 +248,11 @@ void synchronize_rcu(void)
/*
* Must finish waiting for quiescent state for original parity
- * before committing next rcu_gp_ctr update to memory. Failure
+ * before committing next rcu_gp.ctr update to memory. Failure
* to do so could result in the writer waiting forever while new
* readers are always accessing data (no progress). Enforce
* compiler-order of load URCU_TLS(rcu_reader).ctr before store
- * to rcu_gp_ctr.
+ * to rcu_gp.ctr.
*/
cmm_barrier();
@@ -269,13 +264,13 @@ void synchronize_rcu(void)
cmm_smp_mb();
/* Switch parity: 0 -> 1, 1 -> 0 */
- CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR);
+ CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR);
/*
- * Must commit rcu_gp_ctr update to memory before waiting for
+ * Must commit rcu_gp.ctr update to memory before waiting for
* quiescent state. Failure to do so could result in the writer
* waiting forever while new readers are always accessing data
- * (no progress). Enforce compiler-order of store to rcu_gp_ctr
+ * (no progress). Enforce compiler-order of store to rcu_gp.ctr
* before load URCU_TLS(rcu_reader).ctr.
*/
cmm_barrier();
@@ -353,13 +348,13 @@ void synchronize_rcu(void)
goto out;
/* Increment current G.P. */
- CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR);
+ CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr + RCU_GP_CTR);
/*
- * Must commit rcu_gp_ctr update to memory before waiting for
+ * Must commit rcu_gp.ctr update to memory before waiting for
* quiescent state. Failure to do so could result in the writer
* waiting forever while new readers are always accessing data
- * (no progress). Enforce compiler-order of store to rcu_gp_ctr
+ * (no progress). Enforce compiler-order of store to rcu_gp.ctr
* before load URCU_TLS(rcu_reader).ctr.
*/
cmm_barrier();
diff --git a/urcu.c b/urcu.c
index 15def09..782c42e 100644
--- a/urcu.c
+++ b/urcu.c
@@ -83,16 +83,8 @@ void __attribute__((destructor)) rcu_exit(void);
#endif
static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
-
-int32_t rcu_gp_futex;
-
-/*
- * Global grace period counter.
- * Contains the current RCU_GP_CTR_PHASE.
- * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path.
- * Written to only by writer with mutex taken. Read by both writer and readers.
- */
-unsigned long rcu_gp_ctr = RCU_GP_COUNT;
+/* Init the ctr as RCU_GP_COUNT, to accelerate the reader fast path. */
+struct urcu_gp rcu_gp = { { .ctr = RCU_GP_COUNT } };
/*
* Written to only by each individual reader. Read by both the reader and the
@@ -217,8 +209,8 @@ static void wait_gp(void)
{
/* Read reader_gp before read futex */
smp_mb_master(RCU_MB_GROUP);
- if (uatomic_read(&rcu_gp_futex) == -1)
- futex_async(&rcu_gp_futex, FUTEX_WAIT, -1,
+ if (uatomic_read(&rcu_gp.futex) == -1)
+ futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
NULL, NULL, 0);
}
@@ -232,12 +224,12 @@ static void wait_for_readers(struct cds_list_head *input_readers,
/*
* Wait for each thread URCU_TLS(rcu_reader).ctr to either
* indicate quiescence (not nested), or observe the current
- * rcu_gp_ctr value.
+ * rcu_gp.ctr value.
*/
for (;;) {
wait_loops++;
if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
- uatomic_dec(&rcu_gp_futex);
+ uatomic_dec(&rcu_gp.futex);
/* Write futex before read reader_gp */
smp_mb_master(RCU_MB_GROUP);
}
@@ -270,7 +262,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
smp_mb_master(RCU_MB_GROUP);
- uatomic_set(&rcu_gp_futex, 0);
+ uatomic_set(&rcu_gp.futex, 0);
}
break;
} else {
@@ -289,7 +281,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
smp_mb_master(RCU_MB_GROUP);
- uatomic_set(&rcu_gp_futex, 0);
+ uatomic_set(&rcu_gp.futex, 0);
}
break;
} else {
@@ -357,10 +349,10 @@ void synchronize_rcu(void)
/*
* Must finish waiting for quiescent state for original parity before
- * committing next rcu_gp_ctr update to memory. Failure to do so could
+ * committing next rcu_gp.ctr update to memory. Failure to do so could
* result in the writer waiting forever while new readers are always
* accessing data (no progress). Enforce compiler-order of load
- * URCU_TLS(rcu_reader).ctr before store to rcu_gp_ctr.
+ * URCU_TLS(rcu_reader).ctr before store to rcu_gp.ctr.
*/
cmm_barrier();
@@ -372,13 +364,13 @@ void synchronize_rcu(void)
cmm_smp_mb();
/* Switch parity: 0 -> 1, 1 -> 0 */
- CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+ CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR_PHASE);
/*
- * Must commit rcu_gp_ctr update to memory before waiting for quiescent
+ * Must commit rcu_gp.ctr update to memory before waiting for quiescent
* state. Failure to do so could result in the writer waiting forever
* while new readers are always accessing data (no progress). Enforce
- * compiler-order of store to rcu_gp_ctr before load rcu_reader ctr.
+ * compiler-order of store to rcu_gp.ctr before load rcu_reader ctr.
*/
cmm_barrier();
diff --git a/urcu/map/urcu-bp.h b/urcu/map/urcu-bp.h
index 63582fd..0464d3b 100644
--- a/urcu/map/urcu-bp.h
+++ b/urcu/map/urcu-bp.h
@@ -44,8 +44,7 @@
#define rcu_exit rcu_exit_bp
#define synchronize_rcu synchronize_rcu_bp
#define rcu_reader rcu_reader_bp
-#define rcu_gp_ctr rcu_gp_ctr_bp
-#define rcu_gp_futex rcu_gp_futex_bp /* unused */
+#define rcu_gp rcu_gp_bp
#define get_cpu_call_rcu_data get_cpu_call_rcu_data_bp
#define get_call_rcu_thread get_call_rcu_thread_bp
diff --git a/urcu/map/urcu-qsbr.h b/urcu/map/urcu-qsbr.h
index f0aecc9..2c22baf 100644
--- a/urcu/map/urcu-qsbr.h
+++ b/urcu/map/urcu-qsbr.h
@@ -47,8 +47,7 @@
#define rcu_exit rcu_exit_qsbr
#define synchronize_rcu synchronize_rcu_qsbr
#define rcu_reader rcu_reader_qsbr
-#define rcu_gp_ctr rcu_gp_ctr_qsbr
-#define rcu_gp_futex rcu_gp_futex_qsbr
+#define rcu_gp rcu_gp_qsbr
#define get_cpu_call_rcu_data get_cpu_call_rcu_data_qsbr
#define get_call_rcu_thread get_call_rcu_thread_qsbr
diff --git a/urcu/map/urcu.h b/urcu/map/urcu.h
index 759cb41..5ef3d4f 100644
--- a/urcu/map/urcu.h
+++ b/urcu/map/urcu.h
@@ -75,8 +75,7 @@
#define rcu_exit rcu_exit_memb
#define synchronize_rcu synchronize_rcu_memb
#define rcu_reader rcu_reader_memb
-#define rcu_gp_ctr rcu_gp_ctr_memb
-#define rcu_gp_futex rcu_gp_futex_memb
+#define rcu_gp rcu_gp_memb
#define get_cpu_call_rcu_data get_cpu_call_rcu_data_memb
#define get_call_rcu_thread get_call_rcu_thread_memb
@@ -121,8 +120,7 @@
#define rcu_exit rcu_exit_sig
#define synchronize_rcu synchronize_rcu_sig
#define rcu_reader rcu_reader_sig
-#define rcu_gp_ctr rcu_gp_ctr_sig
-#define rcu_gp_futex rcu_gp_futex_sig
+#define rcu_gp rcu_gp_sig
#define get_cpu_call_rcu_data get_cpu_call_rcu_data_sig
#define get_call_rcu_thread get_call_rcu_thread_sig
@@ -164,8 +162,7 @@
#define rcu_exit rcu_exit_mb
#define synchronize_rcu synchronize_rcu_mb
#define rcu_reader rcu_reader_mb
-#define rcu_gp_ctr rcu_gp_ctr_mb
-#define rcu_gp_futex rcu_gp_futex_mb
+#define rcu_gp rcu_gp_mb
#define get_cpu_call_rcu_data get_cpu_call_rcu_data_mb
#define get_call_rcu_thread get_call_rcu_thread_mb
diff --git a/urcu/static/urcu-bp.h b/urcu/static/urcu-bp.h
index c7f5326..a773a01 100644
--- a/urcu/static/urcu-bp.h
+++ b/urcu/static/urcu-bp.h
@@ -130,12 +130,17 @@ static inline void rcu_debug_yield_init(void)
*/
extern void rcu_bp_register(void);
-/*
- * Global quiescent period counter with low-order bits unused.
- * Using a int rather than a char to eliminate false register dependencies
- * causing stalls on some architectures.
- */
-extern unsigned long rcu_gp_ctr;
+struct urcu_gp {
+ /*
+ * Global quiescent period counter with low-order bits unused.
+ * Contains the current RCU_GP_CTR_PHASE.
+ * Written to only by writer with mutex taken.
+ * Read by both writer and readers.
+ */
+ unsigned long ctr;
+} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+
+extern struct urcu_gp rcu_gp;
struct rcu_reader {
/* Data used by both reader and synchronize_rcu() */
@@ -166,13 +171,13 @@ static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
v = CMM_LOAD_SHARED(*ctr);
if (!(v & RCU_GP_CTR_NEST_MASK))
return RCU_READER_INACTIVE;
- if (!((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE))
+ if (!((v ^ rcu_gp.ctr) & RCU_GP_CTR_PHASE))
return RCU_READER_ACTIVE_CURRENT;
return RCU_READER_ACTIVE_OLD;
}
/*
- * Helper for _rcu_read_lock(). The format of rcu_gp_ctr (as well as
+ * Helper for _rcu_read_lock(). The format of rcu_gp.ctr (as well as
* the per-thread rcu_reader.ctr) has the upper bits containing a count of
* _rcu_read_lock() nesting, and a lower-order bit that contains either zero
* or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in
@@ -181,7 +186,7 @@ static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
static inline void _rcu_read_lock_update(unsigned long tmp)
{
if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, _CMM_LOAD_SHARED(rcu_gp_ctr));
+ _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, _CMM_LOAD_SHARED(rcu_gp.ctr));
cmm_smp_mb();
} else
_CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, tmp + RCU_GP_COUNT);
diff --git a/urcu/static/urcu-qsbr.h b/urcu/static/urcu-qsbr.h
index f6e5580..d7a1e1c 100644
--- a/urcu/static/urcu-qsbr.h
+++ b/urcu/static/urcu-qsbr.h
@@ -119,12 +119,23 @@ static inline void rcu_debug_yield_init(void)
#define RCU_GP_ONLINE (1UL << 0)
#define RCU_GP_CTR (1UL << 1)
-/*
- * Global quiescent period counter with low-order bits unused.
- * Using a int rather than a char to eliminate false register dependencies
- * causing stalls on some architectures.
- */
-extern unsigned long rcu_gp_ctr;
+struct urcu_gp {
+ union {
+ /*
+ * Global quiescent period counter with low-order bits unused.
+ * Using a int rather than a char to eliminate false register
+ * dependencies causing stalls on some architectures.
+ */
+ unsigned long ctr;
+
+ /* ensure the futex is located at offset=8 */
+ int64_t __unused;
+ };
+
+ int32_t futex;
+} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+
+extern struct urcu_gp rcu_gp;
struct rcu_reader {
/* Data used by both reader and synchronize_rcu() */
@@ -137,8 +148,6 @@ struct rcu_reader {
extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader);
-extern int32_t rcu_gp_futex;
-
/*
* Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
*/
@@ -147,10 +156,10 @@ static inline void wake_up_gp(void)
if (caa_unlikely(_CMM_LOAD_SHARED(URCU_TLS(rcu_reader).waiting))) {
_CMM_STORE_SHARED(URCU_TLS(rcu_reader).waiting, 0);
cmm_smp_mb();
- if (uatomic_read(&rcu_gp_futex) != -1)
+ if (uatomic_read(&rcu_gp.futex) != -1)
return;
- uatomic_set(&rcu_gp_futex, 0);
- futex_noasync(&rcu_gp_futex, FUTEX_WAKE, 1,
+ uatomic_set(&rcu_gp.futex, 0);
+ futex_noasync(&rcu_gp.futex, FUTEX_WAKE, 1,
NULL, NULL, 0);
}
}
@@ -162,7 +171,7 @@ static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
v = CMM_LOAD_SHARED(*ctr);
if (!v)
return RCU_READER_INACTIVE;
- if (v == rcu_gp_ctr)
+ if (v == rcu_gp.ctr)
return RCU_READER_ACTIVE_CURRENT;
return RCU_READER_ACTIVE_OLD;
}
@@ -216,7 +225,7 @@ static inline void _rcu_quiescent_state_update_and_wakeup(unsigned long gp_ctr)
* to be invoked directly from non-LGPL code.
*
* We skip the memory barriers and gp store if our local ctr already
- * matches the global rcu_gp_ctr value: this is OK because a prior
+ * matches the global rcu_gp.ctr value: this is OK because a prior
* _rcu_quiescent_state() or _rcu_thread_online() already updated it
* within our thread, so we have no quiescent state to report.
*/
@@ -224,7 +233,7 @@ static inline void _rcu_quiescent_state(void)
{
unsigned long gp_ctr;
- if ((gp_ctr = CMM_LOAD_SHARED(rcu_gp_ctr)) == URCU_TLS(rcu_reader).ctr)
+ if ((gp_ctr = CMM_LOAD_SHARED(rcu_gp.ctr)) == URCU_TLS(rcu_reader).ctr)
return;
_rcu_quiescent_state_update_and_wakeup(gp_ctr);
}
@@ -257,7 +266,7 @@ static inline void _rcu_thread_offline(void)
static inline void _rcu_thread_online(void)
{
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, CMM_LOAD_SHARED(rcu_gp_ctr));
+ _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, CMM_LOAD_SHARED(rcu_gp.ctr));
cmm_smp_mb();
}
diff --git a/urcu/static/urcu.h b/urcu/static/urcu.h
index 973826a..d23e673 100644
--- a/urcu/static/urcu.h
+++ b/urcu/static/urcu.h
@@ -213,12 +213,24 @@ static inline void smp_mb_slave(int group)
#define RCU_GP_CTR_PHASE (1UL << (sizeof(unsigned long) << 2))
#define RCU_GP_CTR_NEST_MASK (RCU_GP_CTR_PHASE - 1)
-/*
- * Global quiescent period counter with low-order bits unused.
- * Using a int rather than a char to eliminate false register dependencies
- * causing stalls on some architectures.
- */
-extern unsigned long rcu_gp_ctr;
+struct urcu_gp {
+ union {
+ /*
+ * Global grace period counter.
+ * Contains the current RCU_GP_CTR_PHASE.
+ * Written to only by writer with mutex taken.
+ * Read by both writer and readers.
+ */
+ unsigned long ctr;
+
+ /* ensure the futex is located at offset=8 */
+ int64_t __unused;
+ };
+
+ int32_t futex;
+} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+
+extern struct urcu_gp rcu_gp;
struct rcu_reader {
/* Data used by both reader and synchronize_rcu() */
@@ -231,16 +243,14 @@ struct rcu_reader {
extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader);
-extern int32_t rcu_gp_futex;
-
/*
* Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
*/
static inline void wake_up_gp(void)
{
- if (caa_unlikely(uatomic_read(&rcu_gp_futex) == -1)) {
- uatomic_set(&rcu_gp_futex, 0);
- futex_async(&rcu_gp_futex, FUTEX_WAKE, 1,
+ if (caa_unlikely(uatomic_read(&rcu_gp.futex) == -1)) {
+ uatomic_set(&rcu_gp.futex, 0);
+ futex_async(&rcu_gp.futex, FUTEX_WAKE, 1,
NULL, NULL, 0);
}
}
@@ -256,13 +266,13 @@ static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
v = CMM_LOAD_SHARED(*ctr);
if (!(v & RCU_GP_CTR_NEST_MASK))
return RCU_READER_INACTIVE;
- if (!((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE))
+ if (!((v ^ rcu_gp.ctr) & RCU_GP_CTR_PHASE))
return RCU_READER_ACTIVE_CURRENT;
return RCU_READER_ACTIVE_OLD;
}
/*
- * Helper for _rcu_read_lock(). The format of rcu_gp_ctr (as well as
+ * Helper for _rcu_read_lock(). The format of rcu_gp.ctr (as well as
* the per-thread rcu_reader.ctr) has the upper bits containing a count of
* _rcu_read_lock() nesting, and a lower-order bit that contains either zero
* or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in
@@ -271,7 +281,7 @@ static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
static inline void _rcu_read_lock_update(unsigned long tmp)
{
if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp_ctr));
+ _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, _CMM_LOAD_SHARED(rcu_gp.ctr));
smp_mb_slave(RCU_MB_GROUP);
} else
_CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, tmp + RCU_GP_COUNT);
--
1.7.4.4
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