Module Name: src
Committed By: rmind
Date: Thu Feb 17 18:32:29 UTC 2011
Modified Files:
src/sys/conf: files
src/sys/sys: cpu_data.h lwp.h
Added Files:
src/sys/kern: subr_pcu.c
src/sys/sys: pcu.h
Log Message:
Add PCU (Per-CPU Unit) - an interface to manage synchronization of any
per CPU context tied with an LWP. Main use - lazy FPU handling on SMP.
Requested by matt@, will be used on mips64. Note: implementation will
be improved to use IPIs before adopting on x86. OK ad@.
To generate a diff of this commit:
cvs rdiff -u -r1.998 -r1.999 src/sys/conf/files
cvs rdiff -u -r0 -r1.1 src/sys/kern/subr_pcu.c
cvs rdiff -u -r1.32 -r1.33 src/sys/sys/cpu_data.h
cvs rdiff -u -r1.142 -r1.143 src/sys/sys/lwp.h
cvs rdiff -u -r0 -r1.1 src/sys/sys/pcu.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/conf/files
diff -u src/sys/conf/files:1.998 src/sys/conf/files:1.999
--- src/sys/conf/files:1.998 Wed Feb 9 21:21:32 2011
+++ src/sys/conf/files Thu Feb 17 18:32:29 2011
@@ -1,4 +1,4 @@
-# $NetBSD: files,v 1.998 2011/02/09 21:21:32 macallan Exp $
+# $NetBSD: files,v 1.999 2011/02/17 18:32:29 rmind Exp $
# @(#)files.newconf 7.5 (Berkeley) 5/10/93
version 20100430
@@ -1533,6 +1533,7 @@
file kern/subr_lwp_specificdata.c
file kern/subr_once.c
file kern/subr_optstr.c
+file kern/subr_pcu.c
file kern/subr_percpu.c
file kern/subr_pool.c
file kern/subr_prf.c
Index: src/sys/sys/cpu_data.h
diff -u src/sys/sys/cpu_data.h:1.32 src/sys/sys/cpu_data.h:1.33
--- src/sys/sys/cpu_data.h:1.32 Mon Dec 20 00:25:47 2010
+++ src/sys/sys/cpu_data.h Thu Feb 17 18:32:29 2011
@@ -1,4 +1,4 @@
-/* $NetBSD: cpu_data.h,v 1.32 2010/12/20 00:25:47 matt Exp $ */
+/* $NetBSD: cpu_data.h,v 1.33 2011/02/17 18:32:29 rmind Exp $ */
/*-
* Copyright (c) 2004, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -39,6 +39,7 @@
#include <sys/sched.h> /* for schedstate_percpu */
#include <sys/condvar.h>
+#include <sys/pcu.h>
#include <sys/percpu_types.h>
#include <sys/queue.h>
@@ -75,6 +76,8 @@
cpuid_t cpu_core_id;
cpuid_t cpu_smt_id;
+ struct lwp * volatile cpu_pcu_curlwp[PCU_UNIT_COUNT];
+
/*
* This section is mostly CPU-private.
*/
@@ -116,6 +119,7 @@
#define ci_lockstat ci_data.cpu_lockstat
#define ci_spin_locks2 ci_data.cpu_spin_locks2
#define ci_lkdebug_recurse ci_data.cpu_lkdebug_recurse
+#define ci_pcu_curlwp ci_data.cpu_pcu_curlwp
#define ci_package_id ci_data.cpu_package_id
#define ci_core_id ci_data.cpu_core_id
Index: src/sys/sys/lwp.h
diff -u src/sys/sys/lwp.h:1.142 src/sys/sys/lwp.h:1.143
--- src/sys/sys/lwp.h:1.142 Fri Jan 28 16:58:27 2011
+++ src/sys/sys/lwp.h Thu Feb 17 18:32:29 2011
@@ -1,4 +1,4 @@
-/* $NetBSD: lwp.h,v 1.142 2011/01/28 16:58:27 pooka Exp $ */
+/* $NetBSD: lwp.h,v 1.143 2011/02/17 18:32:29 rmind Exp $ */
/*-
* Copyright (c) 2001, 2006, 2007, 2008, 2009, 2010
@@ -39,6 +39,7 @@
#include <sys/callout.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
+#include <sys/pcu.h>
#include <sys/signalvar.h>
#include <sys/sched.h>
#include <sys/specificdata.h>
@@ -123,6 +124,9 @@
callout_t l_timeout_ch; /* !: callout for tsleep */
u_int l_emap_gen; /* !: emap generation number */
+ struct cpu_info * volatile l_pcu_cpu[PCU_UNIT_COUNT];
+ uint32_t l_pcu_used;
+
/* Process level and global state, misc. */
LIST_ENTRY(lwp) l_list; /* a: entry on list of all LWPs */
void *l_ctxlink; /* p: uc_link {get,set}context */
Added files:
Index: src/sys/kern/subr_pcu.c
diff -u /dev/null src/sys/kern/subr_pcu.c:1.1
--- /dev/null Thu Feb 17 18:32:29 2011
+++ src/sys/kern/subr_pcu.c Thu Feb 17 18:32:29 2011
@@ -0,0 +1,258 @@
+/* $NetBSD: subr_pcu.c,v 1.1 2011/02/17 18:32:29 rmind Exp $ */
+
+/*-
+ * Copyright (c) 2011 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Mindaugas Rasiukevicius.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Per CPU Unit (PCU) - is an interface to manage synchronization of any
+ * per CPU context (unit) tied with LWP context. Typical use: FPU state.
+ *
+ * Concurrency notes:
+ *
+ * PCU state may be loaded only by the current LWP, that is, curlwp.
+ * Therefore, only LWP itself can set a CPU for lwp_t::l_pcu_cpu[id].
+ *
+ * Request for a PCU release can be from owner LWP (whether PCU state
+ * is on current CPU or remote CPU) or any other LWP running on that
+ * CPU (in such case, owner LWP is on a remote CPU or sleeping).
+ *
+ * In any case, PCU state can only be changed from the running CPU.
+ * If said PCU state is on the remote CPU, a cross-call will be sent
+ * by the owner LWP. Therefore struct cpu_info::ci_pcu_curlwp[id]
+ * may only be changed by current CPU, and lwp_t::l_pcu_cpu[id] may
+ * only be unset by the CPU which has PCU state loaded.
+ *
+ * There is a race condition: LWP may have a PCU state on a remote CPU,
+ * which it requests to be released via cross-call. At the same time,
+ * other LWP on remote CPU might release existing PCU state and load
+ * its own one. Cross-call may arrive after this and release different
+ * PCU state than intended. In such case, such LWP would re-load its
+ * PCU state again.
+ */
+
+#include <sys/cdefs.h>
+__KERNEL_RCSID(0, "$NetBSD: subr_pcu.c,v 1.1 2011/02/17 18:32:29 rmind Exp $");
+
+#include <sys/param.h>
+#include <sys/cpu.h>
+#include <sys/lwp.h>
+#include <sys/pcu.h>
+#include <sys/xcall.h>
+
+#define PCU_SAVE 0x01 /* Save PCU state to the LWP. */
+#define PCU_RELEASE 0x02 /* Release PCU state on the CPU. */
+
+#if 0
+/*
+ * pcu_init_lwp: initialize PCU structures for LWP.
+ */
+void
+pcu_init_lwp(lwp_t *l)
+{
+
+ memset(l->l_pcu_cpu, 0, sizeof(uint32_t) * PCU_UNIT_COUNT);
+ l->l_pcu_used = 0;
+}
+#endif
+
+/*
+ * pcu_cpu_op: save/release PCU state on the current CPU.
+ *
+ * => Must be called at IPL_SOFTCLOCK or from the soft-interrupt.
+ */
+static void
+pcu_cpu_op(const pcu_ops_t *pcu, const int flags)
+{
+ const u_int id = pcu->pcu_id;
+ struct cpu_info *ci = curcpu();
+ lwp_t *l = ci->ci_pcu_curlwp[id];
+
+ /* If no state - nothing to do. */
+ if (l == NULL) {
+ return;
+ }
+ if (flags & PCU_SAVE) {
+ pcu->pcu_state_save(l);
+ }
+ if (flags & PCU_RELEASE) {
+ ci->ci_pcu_curlwp[id] = NULL;
+ l->l_pcu_cpu[id] = NULL;
+ }
+}
+
+/*
+ * pcu_lwp_op: perform PCU state save, release or both operations on LWP.
+ */
+static void
+pcu_lwp_op(const pcu_ops_t *pcu, lwp_t *l, int flags)
+{
+ const u_int id = pcu->pcu_id;
+ struct cpu_info *ci;
+ uint64_t where;
+ int s;
+
+ /*
+ * Caller should have re-checked if there is any state to manage.
+ * Block the interrupts and inspect again, since cross-call sent
+ * by remote CPU could have changed the state.
+ */
+ s = splsoftclock();
+ ci = l->l_pcu_cpu[id];
+ if (ci == curcpu()) {
+ /*
+ * State is on the current CPU - just perform the operations.
+ */
+ KASSERT(ci->ci_pcu_curlwp[id] == l);
+
+ if (flags & PCU_SAVE) {
+ pcu->pcu_state_save(l);
+ }
+ if (flags & PCU_RELEASE) {
+ ci->ci_pcu_curlwp[id] = NULL;
+ l->l_pcu_cpu[id] = NULL;
+ }
+ splx(s);
+ return;
+ }
+ splx(s);
+
+ if (__predict_false(ci == NULL)) {
+ /* Cross-call has won the race - no state to manage. */
+ return;
+ }
+
+ /*
+ * State is on the remote CPU - perform the operations there.
+ * Note: there is a race condition; see description in the top.
+ */
+ where = xc_unicast(XC_HIGHPRI, (xcfunc_t)pcu_cpu_op,
+ __UNCONST(pcu), (void *)(uintptr_t)flags, ci);
+ xc_wait(where);
+
+ KASSERT((flags & PCU_RELEASE) == 0 || l->l_pcu_cpu[id] == NULL);
+}
+
+/*
+ * pcu_load: load/initialize the PCU state of current LWP on current CPU.
+ */
+void
+pcu_load(const pcu_ops_t *pcu)
+{
+ const u_int id = pcu->pcu_id;
+ struct cpu_info *ci, *curci;
+ lwp_t *l = curlwp;
+ uint64_t where;
+ int s;
+
+ KASSERT(!cpu_intr_p() && !cpu_softintr_p());
+
+ s = splsoftclock();
+ curci = curcpu();
+ ci = l->l_pcu_cpu[id];
+
+ /* Does this CPU already have our PCU state loaded? */
+ if (ci == curci) {
+ KASSERT(curci->ci_pcu_curlwp[id] == l);
+ splx(s);
+ return;
+ }
+
+ /* If PCU state of this LWP is on the remote CPU - save it there. */
+ if (ci) {
+ splx(s);
+ /* Note: there is a race; see description in the top. */
+ where = xc_unicast(XC_HIGHPRI, (xcfunc_t)pcu_cpu_op,
+ __UNCONST(pcu), (void *)(PCU_SAVE | PCU_RELEASE), ci);
+ xc_wait(where);
+
+ /* Enter IPL_SOFTCLOCK and re-fetch the current CPU. */
+ s = splsoftclock();
+ curci = curcpu();
+ }
+ KASSERT(l->l_pcu_cpu[id] == NULL);
+
+ /* Save the PCU state on the current CPU, if there is any. */
+ pcu_cpu_op(pcu, PCU_SAVE | PCU_RELEASE);
+ KASSERT(curci->ci_pcu_curlwp[id] == NULL);
+
+ /*
+ * Finally, load the state for this LWP on this CPU. Indicate to
+ * load function whether PCU was used before. Note the usage.
+ */
+ pcu->pcu_state_load(l, ((1 << id) & l->l_pcu_used) != 0);
+ curci->ci_pcu_curlwp[id] = l;
+ l->l_pcu_cpu[id] = curci;
+ l->l_pcu_used |= (1 << id);
+ splx(s);
+}
+
+/*
+ * pcu_discard: discard the PCU state of current LWP.
+ */
+void
+pcu_discard(const pcu_ops_t *pcu)
+{
+ const u_int id = pcu->pcu_id;
+ lwp_t *l = curlwp;
+
+ KASSERT(!cpu_intr_p() && !cpu_softintr_p());
+
+ if (__predict_true(l->l_pcu_cpu[id] == NULL)) {
+ return;
+ }
+ pcu_lwp_op(pcu, l, PCU_RELEASE);
+ l->l_pcu_used &= ~(1 << id);
+}
+
+/*
+ * pcu_save_lwp: save PCU state to the given LWP.
+ */
+void
+pcu_save_lwp(const pcu_ops_t *pcu, lwp_t *l)
+{
+ const u_int id = pcu->pcu_id;
+
+ KASSERT(!cpu_intr_p() && !cpu_softintr_p());
+
+ if (__predict_true(l->l_pcu_cpu[id] == NULL)) {
+ return;
+ }
+ pcu_lwp_op(pcu, l, PCU_SAVE | PCU_RELEASE);
+}
+
+/*
+ * pcu_used: return true if PCU was used (pcu_load() case) by the LWP.
+ */
+bool
+pcu_used(const pcu_ops_t *pcu, lwp_t *l)
+{
+ const u_int id = pcu->pcu_id;
+
+ return l->l_pcu_used & (1 << id);
+}
Index: src/sys/sys/pcu.h
diff -u /dev/null src/sys/sys/pcu.h:1.1
--- /dev/null Thu Feb 17 18:32:29 2011
+++ src/sys/sys/pcu.h Thu Feb 17 18:32:29 2011
@@ -0,0 +1,57 @@
+/* $NetBSD: pcu.h,v 1.1 2011/02/17 18:32:29 rmind Exp $ */
+
+/*-
+ * Copyright (c) 2011 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Mindaugas Rasiukevicius.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _SYS_PCU_H_
+#define _SYS_PCU_H_
+
+#if !defined(_KERNEL) && !defined(_KMEMUSER)
+#error "Kernel-only header"
+#endif
+
+/*
+ * Default: one PCU for MD.
+ */
+#ifndef PCU_UNIT_COUNT
+#define PCU_UNIT_COUNT 1
+#endif
+
+typedef struct {
+ u_int pcu_id;
+ void (*pcu_state_save)(lwp_t *);
+ void (*pcu_state_load)(lwp_t *, bool);
+} pcu_ops_t;
+
+void pcu_load(const pcu_ops_t *);
+void pcu_save_lwp(const pcu_ops_t *, lwp_t *);
+void pcu_discard(const pcu_ops_t *);
+bool pcu_used(const pcu_ops_t *, lwp_t *);
+
+#endif
