[ltt-dev] [PATCH RFC] call_rcu() interface for userspace-rcu
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Fri Oct 29 13:02:36 EDT 2010
* Paul E. McKenney (paulmck at linux.vnet.ibm.com) wrote:
> Adds call_rcu(), with RCU threads to invoke the callbacks. By default,
> there will be one such RCU thread per process, created the first time
> that call_rcu() is invoked. On systems supporting sched_getcpu(), it
> is possible to create one RCU thread per CPU by calling
> create_all_cpu_call_rcu_data().
Thanks for sending this! Here is some input:
>
> Signed-off-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
>
> diff --git a/Makefile.am b/Makefile.am
> index 79a7152..64bb299 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -29,8 +29,8 @@ COMPAT+=compat_futex.c
> endif
>
> lib_LTLIBRARIES = liburcu.la liburcu-qsbr.la liburcu-mb.la liburcu-signal.la \
> - liburcu-bp.la liburcu-defer.la libwfqueue.la libwfstack.la \
> - librculfqueue.la librculfstack.la
> + liburcu-bp.la liburcu-defer.la liburcu-call.la \
> + libwfqueue.la libwfstack.la librculfqueue.la librculfstack.la
>
> liburcu_la_SOURCES = urcu.c urcu-pointer.c $(COMPAT)
>
> @@ -44,6 +44,7 @@ liburcu_signal_la_CFLAGS = -DRCU_SIGNAL
>
> liburcu_bp_la_SOURCES = urcu-bp.c urcu-pointer.c $(COMPAT)
>
> +liburcu_call_la_SOURCES = urcu-call-rcu.c $(COMPAT)
> liburcu_defer_la_SOURCES = urcu-defer.c $(COMPAT)
>
> libwfqueue_la_SOURCES = wfqueue.c $(COMPAT)
> diff --git a/configure.ac b/configure.ac
> index 89bdb6c..083ed95 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -34,7 +34,7 @@ AC_TYPE_SIZE_T
> # Checks for library functions.
> AC_FUNC_MALLOC
> AC_FUNC_MMAP
> -AC_CHECK_FUNCS([bzero gettimeofday munmap strtoul])
> +AC_CHECK_FUNCS([bzero gettimeofday munmap sched_getcpu strtoul sysconf])
>
> # Find arch type
> case $host_cpu in
> diff --git a/tests/Makefile.am b/tests/Makefile.am
> index a43dd75..3c025a4 100644
> --- a/tests/Makefile.am
> +++ b/tests/Makefile.am
> @@ -1,5 +1,5 @@
> AM_LDFLAGS=-lpthread
> -AM_CFLAGS=-I$(top_srcdir) -I$(top_builddir)
> +AM_CFLAGS=-I$(top_srcdir) -I$(top_builddir) -g
>
> noinst_PROGRAMS = test_urcu test_urcu_dynamic_link test_urcu_timing \
> test_urcu_signal test_urcu_signal_dynamic_link test_urcu_signal_timing \
> @@ -28,20 +28,21 @@ if COMPAT_FUTEX
> COMPAT+=$(top_srcdir)/compat_futex.c
> endif
>
> -URCU=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-pointer.c $(COMPAT)
> -URCU_QSBR=$(top_srcdir)/urcu-qsbr.c $(top_srcdir)/urcu-pointer.c $(COMPAT)
> +URCU=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-pointer.c $(top_srcdir)/urcu-call-rcu.c $(top_srcdir)/wfqueue.c $(COMPAT)
> +URCU_QSBR=$(top_srcdir)/urcu-qsbr.c $(top_srcdir)/urcu-pointer.c $(top_srcdir)/urcu-call-rcu.c $(top_srcdir)/wfqueue.c $(COMPAT)
> # URCU_MB uses urcu.c but -DRCU_MB must be defined
> -URCU_MB=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-pointer.c $(COMPAT)
> +URCU_MB=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-pointer.c $(top_srcdir)/urcu-call-rcu.c $(top_srcdir)/wfqueue.c $(COMPAT)
> # URCU_SIGNAL uses urcu.c but -DRCU_SIGNAL must be defined
> -URCU_SIGNAL=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-pointer.c $(COMPAT)
> -URCU_BP=$(top_srcdir)/urcu-bp.c $(top_srcdir)/urcu-pointer.c $(COMPAT)
> -URCU_DEFER=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-defer.c $(top_srcdir)/urcu-pointer.c $(COMPAT)
> +URCU_SIGNAL=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-pointer.c $(top_srcdir)/urcu-call-rcu.c $(top_srcdir)/wfqueue.c $(COMPAT)
> +URCU_BP=$(top_srcdir)/urcu-bp.c $(top_srcdir)/urcu-pointer.c $(top_srcdir)/urcu-call-rcu.c $(top_srcdir)/wfqueue.c $(COMPAT)
> +URCU_DEFER=$(top_srcdir)/urcu.c $(top_srcdir)/urcu-defer.c $(top_srcdir)/urcu-pointer.c $(top_srcdir)/urcu-call-rcu.c $(top_srcdir)/wfqueue.c $(COMPAT)
>
> URCU_LIB=$(top_builddir)/liburcu.la
> URCU_QSBR_LIB=$(top_builddir)/liburcu-qsbr.la
> URCU_MB_LIB=$(top_builddir)/liburcu-mb.la
> URCU_SIGNAL_LIB=$(top_builddir)/liburcu-signal.la
> URCU_BP_LIB=$(top_builddir)/liburcu-bp.la
> +URCU_CALL_LIB=$(top_builddir)/liburcu-call.la
> WFQUEUE_LIB=$(top_builddir)/libwfqueue.la
> WFSTACK_LIB=$(top_builddir)/libwfstack.la
> RCULFQUEUE_LIB=$(top_builddir)/librculfqueue.la
> @@ -95,23 +96,23 @@ test_perthreadlock_SOURCES = test_perthreadlock.c $(URCU_SIGNAL)
>
> rcutorture_urcu_SOURCES = urcutorture.c
> rcutorture_urcu_CFLAGS = -DTORTURE_URCU $(AM_CFLAGS)
> -rcutorture_urcu_LDADD = $(URCU)
> +rcutorture_urcu_LDADD = $(URCU) $(URCU_CALL_LIB) $(WFQUEUE_LIB)
>
> rcutorture_urcu_mb_SOURCES = urcutorture.c
> rcutorture_urcu_mb_CFLAGS = -DTORTURE_URCU_MB $(AM_CFLAGS)
> -rcutorture_urcu_mb_LDADD = $(URCU_MB_LIB)
> +rcutorture_urcu_mb_LDADD = $(URCU_MB_LIB) $(URCU_CALL_LIB) $(WFQUEUE_LIB)
>
> rcutorture_qsbr_SOURCES = urcutorture.c
> rcutorture_qsbr_CFLAGS = -DTORTURE_QSBR $(AM_CFLAGS)
> -rcutorture_qsbr_LDADD = $(URCU_QSBR_LIB)
> +rcutorture_qsbr_LDADD = $(URCU_QSBR_LIB) $(URCU_CALL_LIB) $(WFQUEUE_LIB)
>
> rcutorture_urcu_signal_SOURCES = urcutorture.c
> rcutorture_urcu_signal_CFLAGS = -DTORTURE_URCU_SIGNAL $(AM_CFLAGS)
> -rcutorture_urcu_signal_LDADD = $(URCU_SIGNAL_LIB)
> +rcutorture_urcu_signal_LDADD = $(URCU_SIGNAL_LIB) $(URCU_CALL_LIB) $(WFQUEUE_LIB)
>
> rcutorture_urcu_bp_SOURCES = urcutorture.c
> rcutorture_urcu_bp_CFLAGS = -DTORTURE_URCU_BP $(AM_CFLAGS)
> -rcutorture_urcu_bp_LDADD = $(URCU_BP_LIB)
> +rcutorture_urcu_bp_LDADD = $(URCU_BP_LIB) $(URCU_CALL_LIB) $(WFQUEUE_LIB)
>
> test_mutex_SOURCES = test_mutex.c $(URCU)
>
> diff --git a/tests/rcutorture.h b/tests/rcutorture.h
> index 181547a..1970d33 100644
> --- a/tests/rcutorture.h
> +++ b/tests/rcutorture.h
> @@ -65,6 +65,8 @@
> * Test variables.
> */
>
> +#include "../urcu-call-rcu.h"
> +
> DEFINE_PER_THREAD(long long, n_reads_pt);
> DEFINE_PER_THREAD(long long, n_updates_pt);
>
> @@ -296,10 +298,30 @@ void *rcu_read_stress_test(void *arg)
> return (NULL);
> }
>
> +static pthread_mutex_t call_rcu_test_mutex = PTHREAD_MUTEX_INITIALIZER;
> +static pthread_cond_t call_rcu_test_cond = PTHREAD_COND_INITIALIZER;
> +
> +void rcu_update_stress_test_rcu(struct rcu_head *head)
> +{
> + if (pthread_mutex_lock(&call_rcu_test_mutex) != 0) {
> + perror("pthread_mutex_lock");
> + exit(-1);
> + }
> + if (pthread_cond_signal(&call_rcu_test_cond) != 0) {
> + perror("pthread_cond_signal");
> + exit(-1);
> + }
> + if (pthread_mutex_unlock(&call_rcu_test_mutex) != 0) {
> + perror("pthread_mutex_unlock");
> + exit(-1);
> + }
> +}
> +
> void *rcu_update_stress_test(void *arg)
> {
> int i;
> struct rcu_stress *p;
> + struct rcu_head rh;
>
> while (goflag == GOFLAG_INIT)
> poll(NULL, 0, 1);
> @@ -317,7 +339,24 @@ void *rcu_update_stress_test(void *arg)
> for (i = 0; i < RCU_STRESS_PIPE_LEN; i++)
> if (i != rcu_stress_idx)
> rcu_stress_array[i].pipe_count++;
> - synchronize_rcu();
> + if (n_updates & 0x1)
> + synchronize_rcu();
> + else {
> + if (pthread_mutex_lock(&call_rcu_test_mutex) != 0) {
> + perror("pthread_mutex_lock");
> + exit(-1);
> + }
> + call_rcu(&rh, rcu_update_stress_test_rcu);
Testing more than one queue entry would be good.
> + if (pthread_cond_wait(&call_rcu_test_cond,
> + &call_rcu_test_mutex) != 0) {
> + perror("pthread_cond_wait");
> + exit(-1);
> + }
> + if (pthread_mutex_unlock(&call_rcu_test_mutex) != 0) {
> + perror("pthread_mutex_unlock");
> + exit(-1);
> + }
> + }
> n_updates++;
> }
> return NULL;
> diff --git a/urcu-call-rcu.c b/urcu-call-rcu.c
> new file mode 100644
> index 0000000..245fd33
> --- /dev/null
> +++ b/urcu-call-rcu.c
> @@ -0,0 +1,397 @@
> +/*
> + * urcu-call-rcu.c
> + *
> + * Userspace RCU library - batch memory reclamation with kernel API
> + *
> + * Copyright (c) 2010 Paul E. McKenney <paulmck at linux.vnet.ibm.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
> + */
> +
> +#include <stdio.h>
> +#include <pthread.h>
> +#include <signal.h>
> +#include <assert.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <poll.h>
> +#include <sys/time.h>
> +#include <syscall.h>
> +#include <unistd.h>
> +
> +#include "config.h"
> +#include "urcu/wfqueue.h"
> +#include "urcu-call-rcu.h"
> +#include "urcu-pointer.h"
> +
> +/* Data structure that identifies a call_rcu thread. */
> +
> +struct call_rcu_data {
> + struct wfq_queue cbs;
> + unsigned long qlen;
We should probably create a RCU_DEBUG function that tests for large values.
[ more later, after lunch :) ]
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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