Author: jeff
Date: Thu Nov 15 00:51:57 2012
New Revision: 243046
URL: http://svnweb.freebsd.org/changeset/base/243046
Log:
- Implement run-time expansion of the KTR buffer via sysctl.
- Implement a function to ensure that all preempted threads have switched
back out at least once. Use this to make sure there are no stale
references to the old ktr_buf or the lock profiling buffers before
updating them.
Reviewed by: marius (sparc64 parts), attilio (earlier patch)
Sponsored by: EMC / Isilon Storage Division
Modified:
head/sys/kern/kern_ktr.c
head/sys/kern/subr_lock.c
head/sys/kern/subr_smp.c
head/sys/sparc64/include/ktr.h
head/sys/sys/ktr.h
head/sys/sys/smp.h
head/usr.bin/ktrdump/ktrdump.c
Modified: head/sys/kern/kern_ktr.c
==============================================================================
--- head/sys/kern/kern_ktr.c Wed Nov 14 22:21:03 2012 (r243045)
+++ head/sys/kern/kern_ktr.c Thu Nov 15 00:51:57 2012 (r243046)
@@ -47,7 +47,11 @@ __FBSDID("$FreeBSD$");
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/libkern.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
#include <sys/proc.h>
+#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/time.h>
@@ -66,6 +70,9 @@ __FBSDID("$FreeBSD$");
#define KTR_ENTRIES 1024
#endif
+/* Limit the allocations to something manageable. */
+#define KTR_ENTRIES_MAX (8 * 1024 * 1024)
+
#ifndef KTR_MASK
#define KTR_MASK (0)
#endif
@@ -82,30 +89,31 @@ __FBSDID("$FreeBSD$");
#define KTR_CPU PCPU_GET(cpuid)
#endif
-FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
+static MALLOC_DEFINE(M_KTR, "KTR", "KTR");
-static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD, 0, "KTR options");
+FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
+volatile int ktr_idx = 0;
int ktr_mask = KTR_MASK;
+int ktr_compile = KTR_COMPILE;
+int ktr_entries = KTR_ENTRIES;
+int ktr_version = KTR_VERSION;
+struct ktr_entry ktr_buf_init[KTR_ENTRIES];
+struct ktr_entry *ktr_buf = ktr_buf_init;
+cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
+static char ktr_cpumask_str[CPUSETBUFSIZ];
+
TUNABLE_INT("debug.ktr.mask", &ktr_mask);
-SYSCTL_INT(_debug_ktr, OID_AUTO, mask, CTLFLAG_RW,
- &ktr_mask, 0, "Bitmask of KTR event classes for which logging is enabled");
-int ktr_compile = KTR_COMPILE;
-SYSCTL_INT(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
- &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
+TUNABLE_STR("debug.ktr.cpumask", ktr_cpumask_str, sizeof(ktr_cpumask_str));
-int ktr_entries = KTR_ENTRIES;
-SYSCTL_INT(_debug_ktr, OID_AUTO, entries, CTLFLAG_RD,
- &ktr_entries, 0, "Number of entries in the KTR buffer");
+static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD, 0, "KTR options");
-int ktr_version = KTR_VERSION;
SYSCTL_INT(_debug_ktr, OID_AUTO, version, CTLFLAG_RD,
&ktr_version, 0, "Version of the KTR interface");
-cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
-static char ktr_cpumask_str[CPUSETBUFSIZ];
-TUNABLE_STR("debug.ktr.cpumask", ktr_cpumask_str, sizeof(ktr_cpumask_str));
+SYSCTL_INT(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
+ &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
static void
ktr_cpumask_initializer(void *dummy __unused)
@@ -145,9 +153,6 @@ SYSCTL_PROC(_debug_ktr, OID_AUTO, cpumas
sysctl_debug_ktr_cpumask, "S",
"Bitmask of CPUs on which KTR logging is enabled");
-volatile int ktr_idx = 0;
-struct ktr_entry ktr_buf[KTR_ENTRIES];
-
static int
sysctl_debug_ktr_clear(SYSCTL_HANDLER_ARGS)
{
@@ -159,7 +164,7 @@ sysctl_debug_ktr_clear(SYSCTL_HANDLER_AR
return (error);
if (clear) {
- bzero(ktr_buf, sizeof(ktr_buf));
+ bzero(ktr_buf, sizeof(*ktr_buf) * ktr_entries);
ktr_idx = 0;
}
@@ -168,6 +173,67 @@ sysctl_debug_ktr_clear(SYSCTL_HANDLER_AR
SYSCTL_PROC(_debug_ktr, OID_AUTO, clear, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
sysctl_debug_ktr_clear, "I", "Clear KTR Buffer");
+/*
+ * This is a sysctl proc so that it is serialized as !MPSAFE along with
+ * the other ktr sysctl procs.
+ */
+static int
+sysctl_debug_ktr_mask(SYSCTL_HANDLER_ARGS)
+{
+ int mask, error;
+
+ mask = ktr_mask;
+ error = sysctl_handle_int(oidp, &mask, 0, req);
+ if (error || !req->newptr)
+ return (error);
+ ktr_mask = mask;
+ return (error);
+}
+
+SYSCTL_PROC(_debug_ktr, OID_AUTO, mask, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
+ sysctl_debug_ktr_mask, "I",
+ "Bitmask of KTR event classes for which logging is enabled");
+
+static int
+sysctl_debug_ktr_entries(SYSCTL_HANDLER_ARGS)
+{
+ int entries, error, mask;
+ struct ktr_entry *buf, *oldbuf;
+
+ entries = ktr_entries;
+ error = sysctl_handle_int(oidp, &entries, 0, req);
+ if (error || !req->newptr)
+ return (error);
+ if (entries > KTR_ENTRIES_MAX)
+ return (ERANGE);
+ /* Disable ktr temporarily. */
+ mask = ktr_mask;
+ atomic_store_rel_int(&ktr_mask, 0);
+ /* Wait for threads to go idle. */
+ if ((error = quiesce_all_cpus("ktrent", PCATCH)) != 0) {
+ ktr_mask = mask;
+ return (error);
+ }
+ if (ktr_buf != ktr_buf_init)
+ oldbuf = ktr_buf;
+ else
+ oldbuf = NULL;
+ /* Allocate a new buffer. */
+ buf = malloc(sizeof(*buf) * entries, M_KTR, M_WAITOK | M_ZERO);
+ /* Install the new buffer and restart ktr. */
+ ktr_buf = buf;
+ ktr_entries = entries;
+ ktr_idx = 0;
+ atomic_store_rel_int(&ktr_mask, mask);
+ if (oldbuf != NULL)
+ free(oldbuf, M_KTR);
+
+ return (error);
+}
+
+SYSCTL_PROC(_debug_ktr, OID_AUTO, entries, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
+ sysctl_debug_ktr_entries, "I", "Number of entries in the KTR buffer");
+
#ifdef KTR_VERBOSE
int ktr_verbose = KTR_VERBOSE;
TUNABLE_INT("debug.ktr.verbose", &ktr_verbose);
@@ -249,7 +315,7 @@ ktr_tracepoint(u_int mask, const char *f
if (panicstr)
return;
- if ((ktr_mask & mask) == 0)
+ if ((ktr_mask & mask) == 0 || ktr_buf == NULL)
return;
cpu = KTR_CPU;
if (!CPU_ISSET(cpu, &ktr_cpumask))
@@ -281,7 +347,7 @@ ktr_tracepoint(u_int mask, const char *f
{
do {
saveindex = ktr_idx;
- newindex = (saveindex + 1) % KTR_ENTRIES;
+ newindex = (saveindex + 1) % ktr_entries;
} while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex)
== 0);
entry = &ktr_buf[saveindex];
}
@@ -336,7 +402,7 @@ static int db_mach_vtrace(void);
DB_SHOW_COMMAND(ktr, db_ktr_all)
{
- tstate.cur = (ktr_idx - 1) % KTR_ENTRIES;
+ tstate.cur = (ktr_idx - 1) % ktr_entries;
tstate.first = -1;
db_ktr_verbose = 0;
db_ktr_verbose |= (strchr(modif, 'v') != NULL) ? 2 : 0;
@@ -358,7 +424,7 @@ db_mach_vtrace(void)
{
struct ktr_entry *kp;
- if (tstate.cur == tstate.first) {
+ if (tstate.cur == tstate.first || ktr_buf == NULL) {
db_printf("--- End of trace buffer ---\n");
return (0);
}
@@ -390,7 +456,7 @@ db_mach_vtrace(void)
tstate.first = tstate.cur;
if (--tstate.cur < 0)
- tstate.cur = KTR_ENTRIES - 1;
+ tstate.cur = ktr_entries - 1;
return (1);
}
Modified: head/sys/kern/subr_lock.c
==============================================================================
--- head/sys/kern/subr_lock.c Wed Nov 14 22:21:03 2012 (r243045)
+++ head/sys/kern/subr_lock.c Thu Nov 15 00:51:57 2012 (r243046)
@@ -240,34 +240,13 @@ lock_prof_init(void *arg)
}
SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL);
-/*
- * To be certain that lock profiling has idled on all cpus before we
- * reset, we schedule the resetting thread on all active cpus. Since
- * all operations happen within critical sections we can be sure that
- * it is safe to zero the profiling structures.
- */
-static void
-lock_prof_idle(void)
-{
- struct thread *td;
- int cpu;
-
- td = curthread;
- thread_lock(td);
- CPU_FOREACH(cpu) {
- sched_bind(td, cpu);
- }
- sched_unbind(td);
- thread_unlock(td);
-}
-
static void
lock_prof_reset_wait(void)
{
/*
- * Spin relinquishing our cpu so that lock_prof_idle may
- * run on it.
+ * Spin relinquishing our cpu so that quiesce_all_cpus may
+ * complete.
*/
while (lock_prof_resetting)
sched_relinquish(curthread);
@@ -289,7 +268,7 @@ lock_prof_reset(void)
atomic_store_rel_int(&lock_prof_resetting, 1);
enabled = lock_prof_enable;
lock_prof_enable = 0;
- lock_prof_idle();
+ quiesce_all_cpus("profreset", 0);
/*
* Some objects may have migrated between CPUs. Clear all links
* before we zero the structures. Some items may still be linked
@@ -401,7 +380,7 @@ dump_lock_prof_stats(SYSCTL_HANDLER_ARGS
"max", "wait_max", "total", "wait_total", "count", "avg",
"wait_avg", "cnt_hold", "cnt_lock", "name");
enabled = lock_prof_enable;
lock_prof_enable = 0;
- lock_prof_idle();
+ quiesce_all_cpus("profstat", 0);
t = ticks;
for (cpu = 0; cpu <= mp_maxid; cpu++) {
if (lp_cpu[cpu] == NULL)
Modified: head/sys/kern/subr_smp.c
==============================================================================
--- head/sys/kern/subr_smp.c Wed Nov 14 22:21:03 2012 (r243045)
+++ head/sys/kern/subr_smp.c Thu Nov 15 00:51:57 2012 (r243046)
@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/pcpu.h>
+#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
@@ -734,3 +735,52 @@ smp_no_rendevous_barrier(void *dummy)
KASSERT((!smp_started),("smp_no_rendevous called and smp is started"));
#endif
}
+
+/*
+ * Wait specified idle threads to switch once. This ensures that even
+ * preempted threads have cycled through the switch function once,
+ * exiting their codepaths. This allows us to change global pointers
+ * with no other synchronization.
+ */
+int
+quiesce_cpus(cpuset_t map, const char *wmesg, int prio)
+{
+ struct pcpu *pcpu;
+ u_int gen[MAXCPU];
+ int error;
+ int cpu;
+
+ error = 0;
+ for (cpu = 0; cpu <= mp_maxid; cpu++) {
+ if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu))
+ continue;
+ pcpu = pcpu_find(cpu);
+ gen[cpu] = pcpu->pc_idlethread->td_generation;
+ }
+ for (cpu = 0; cpu <= mp_maxid; cpu++) {
+ if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu))
+ continue;
+ pcpu = pcpu_find(cpu);
+ thread_lock(curthread);
+ sched_bind(curthread, cpu);
+ thread_unlock(curthread);
+ while (gen[cpu] == pcpu->pc_idlethread->td_generation) {
+ error = tsleep(quiesce_cpus, prio, wmesg, 1);
+ if (error)
+ goto out;
+ }
+ }
+out:
+ thread_lock(curthread);
+ sched_unbind(curthread);
+ thread_unlock(curthread);
+
+ return (error);
+}
+
+int
+quiesce_all_cpus(const char *wmesg, int prio)
+{
+
+ return quiesce_cpus(all_cpus, wmesg, prio);
+}
Modified: head/sys/sparc64/include/ktr.h
==============================================================================
--- head/sys/sparc64/include/ktr.h Wed Nov 14 22:21:03 2012
(r243045)
+++ head/sys/sparc64/include/ktr.h Thu Nov 15 00:51:57 2012
(r243046)
@@ -58,6 +58,7 @@ l2: add r2, 1, r3 ; \
bne %icc, l2 ## b ; \
mov r3, r2 ; \
SET(ktr_buf, r3, r1) ; \
+ ldx [r1], r1 ; \
mulx r2, KTR_SIZEOF, r2 ; \
add r1, r2, r1 ; \
rd %tick, r2 ; \
Modified: head/sys/sys/ktr.h
==============================================================================
--- head/sys/sys/ktr.h Wed Nov 14 22:21:03 2012 (r243045)
+++ head/sys/sys/ktr.h Thu Nov 15 00:51:57 2012 (r243046)
@@ -116,7 +116,7 @@ extern int ktr_entries;
extern int ktr_verbose;
extern volatile int ktr_idx;
-extern struct ktr_entry ktr_buf[];
+extern struct ktr_entry *ktr_buf;
#ifdef KTR
Modified: head/sys/sys/smp.h
==============================================================================
--- head/sys/sys/smp.h Wed Nov 14 22:21:03 2012 (r243045)
+++ head/sys/sys/smp.h Thu Nov 15 00:51:57 2012 (r243046)
@@ -167,10 +167,14 @@ int stop_cpus_hard(cpuset_t);
#if defined(__amd64__) || defined(__i386__)
int suspend_cpus(cpuset_t);
#endif
+
void smp_rendezvous_action(void);
extern struct mtx smp_ipi_mtx;
#endif /* SMP */
+
+int quiesce_all_cpus(const char *, int);
+int quiesce_cpus(cpuset_t, const char *, int);
void smp_no_rendevous_barrier(void *);
void smp_rendezvous(void (*)(void *),
void (*)(void *),
Modified: head/usr.bin/ktrdump/ktrdump.c
==============================================================================
--- head/usr.bin/ktrdump/ktrdump.c Wed Nov 14 22:21:03 2012
(r243045)
+++ head/usr.bin/ktrdump/ktrdump.c Thu Nov 15 00:51:57 2012
(r243046)
@@ -86,6 +86,7 @@ main(int ac, char **av)
u_long parms[KTR_PARMS];
struct ktr_entry *buf;
uintmax_t tlast, tnow;
+ unsigned long bufptr;
struct stat sb;
kvm_t *kd;
FILE *out;
@@ -179,8 +180,9 @@ main(int ac, char **av)
if ((buf = malloc(sizeof(*buf) * entries)) == NULL)
err(1, NULL);
if (kvm_read(kd, nl[2].n_value, &index, sizeof(index)) == -1 ||
- kvm_read(kd, nl[3].n_value, buf, sizeof(*buf) * entries)
- == -1)
+ kvm_read(kd, nl[3].n_value, &bufptr,
+ sizeof(bufptr)) == -1 ||
+ kvm_read(kd, bufptr, buf, sizeof(*buf) * entries) == -1)
errx(1, "%s", kvm_geterr(kd));
}
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