[ltt-dev] [rp] [PATCH RFC] call_rcu() interface for userspace-rcu
Paul E. McKenney
paulmck at linux.vnet.ibm.com
Fri Oct 29 17:42:44 EDT 2010
On Fri, Oct 29, 2010 at 01:02:36PM -0400, Mathieu Desnoyers wrote:
> * 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.
Good point -- I should enqueue a random number of them.
> > + 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.
There should be something it can be used for... Let me think through some
possibilities.
Thanx, Paul
> [ more later, after lunch :) ]
>
> --
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com
>
> _______________________________________________
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> rp at svcs.cs.pdx.edu
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