[POWERPC] spufs: Add marker-based tracing facility

This adds markers two important points in the spufs code and a new
module (sputrace.ko) that allows reading these out through a proc file.

Long-term I'd rather see something like lttng extended to use the spufs
instrumentation, but for now I think this is a good enough quick
solution.  We'll probably want to add various addition event in addition
to that ones I have already.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

6 files changed, 291 insertions, 7 deletions

diff --git a/arch/powerpc/platforms/cell/Kconfig b/arch/powerpc/platforms/cell/Kconfig
index 3a963b4a9be0..2f169991896d 100644
--- a/arch/powerpc/platforms/cell/Kconfig
+++ b/arch/powerpc/platforms/cell/Kconfig
@@ -54,6 +54,13 @@ config SPU_FS_64K_LS
           uses 4K pages. This can improve performances of applications
           using multiple SPEs by lowering the TLB pressure on them.
 
+config SPU_TRACE
+        tristate "SPU event tracing support"
+        depends on SPU_FS && MARKERS
+        help
+          This option allows reading a trace of spu-related events through
+          the sputrace file in procfs.
+
 config SPU_BASE
         bool
         default n
diff --git a/arch/powerpc/platforms/cell/spufs/Makefile b/arch/powerpc/platforms/cell/spufs/Makefile
index d3a349fb42e5..99610a6361f2 100644
--- a/arch/powerpc/platforms/cell/spufs/Makefile
+++ b/arch/powerpc/platforms/cell/spufs/Makefile
@@ -4,6 +4,8 @@ spufs-y += inode.o file.o context.o syscalls.o coredump.o
 spufs-y += sched.o backing_ops.o hw_ops.o run.o gang.o
 spufs-y += switch.o fault.o lscsa_alloc.o
 
+obj-$(CONFIG_SPU_TRACE) += sputrace.o
+
 # Rules to build switch.o with the help of SPU tool chain
 SPU_CROSS       := spu-
 SPU_CC          := $(SPU_CROSS)gcc
diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index 3fcd06418b01..1018acd1746b 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -29,6 +29,7 @@
 #include <linux/poll.h>
 #include <linux/ptrace.h>
 #include <linux/seq_file.h>
+#include <linux/marker.h>
 
 #include <asm/io.h>
 #include <asm/semaphore.h>
@@ -358,6 +359,8 @@ static unsigned long spufs_ps_nopfn(struct vm_area_struct *vma,
         struct spu_context *ctx = vma->vm_file->private_data;
         unsigned long area, offset = address - vma->vm_start;
 
+        spu_context_nospu_trace(spufs_ps_nopfn__enter, ctx);
+
         offset += vma->vm_pgoff << PAGE_SHIFT;
         if (offset >= ps_size)
                 return NOPFN_SIGBUS;
@@ -375,11 +378,14 @@ static unsigned long spufs_ps_nopfn(struct vm_area_struct *vma,
 
         if (ctx->state == SPU_STATE_SAVED) {
                 up_read(&current->mm->mmap_sem);
+                spu_context_nospu_trace(spufs_ps_nopfn__sleep, ctx);
                 spufs_wait(ctx->run_wq, ctx->state == SPU_STATE_RUNNABLE);
+                spu_context_trace(spufs_ps_nopfn__wake, ctx, ctx->spu);
                 down_read(&current->mm->mmap_sem);
         } else {
                 area = ctx->spu->problem_phys + ps_offs;
                 vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
+                spu_context_trace(spufs_ps_nopfn__insert, ctx, ctx->spu);
         }
 
         spu_release(ctx);
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 00d914232af1..5915343e2599 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -39,6 +39,7 @@
 #include <linux/pid_namespace.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
+#include <linux/marker.h>
 
 #include <asm/io.h>
 #include <asm/mmu_context.h>
@@ -216,8 +217,8 @@ void do_notify_spus_active(void)
  */
 static void spu_bind_context(struct spu *spu, struct spu_context *ctx)
 {
-        pr_debug("%s: pid=%d SPU=%d NODE=%d\n", __FUNCTION__, current->pid,
-                 spu->number, spu->node);
+        spu_context_trace(spu_bind_context__enter, ctx, spu);
+
         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 
         if (ctx->flags & SPU_CREATE_NOSCHED)
@@ -399,8 +400,8 @@ static int has_affinity(struct spu_context *ctx)
  */
 static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
 {
-        pr_debug("%s: unbind pid=%d SPU=%d NODE=%d\n", __FUNCTION__,
-                 spu->pid, spu->number, spu->node);
+        spu_context_trace(spu_unbind_context__enter, ctx, spu);
+
         spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 
         if (spu->ctx->flags & SPU_CREATE_NOSCHED)
@@ -528,6 +529,8 @@ static struct spu *spu_get_idle(struct spu_context *ctx)
         struct spu *spu, *aff_ref_spu;
         int node, n;
 
+        spu_context_nospu_trace(spu_get_idle__enter, ctx);
+
         if (ctx->gang) {
                 mutex_lock(&ctx->gang->aff_mutex);
                 if (has_affinity(ctx)) {
@@ -546,8 +549,7 @@ static struct spu *spu_get_idle(struct spu_context *ctx)
                         if (atomic_dec_and_test(&ctx->gang->aff_sched_count))
                                 ctx->gang->aff_ref_spu = NULL;
                         mutex_unlock(&ctx->gang->aff_mutex);
-
-                        return NULL;
+                        goto not_found;
                 }
                 mutex_unlock(&ctx->gang->aff_mutex);
         }
@@ -565,12 +567,14 @@ static struct spu *spu_get_idle(struct spu_context *ctx)
                 mutex_unlock(&cbe_spu_info[node].list_mutex);
         }
 
+ not_found:
+        spu_context_nospu_trace(spu_get_idle__not_found, ctx);
         return NULL;
 
  found:
         spu->alloc_state = SPU_USED;
         mutex_unlock(&cbe_spu_info[node].list_mutex);
-        pr_debug("Got SPU %d %d\n", spu->number, spu->node);
+        spu_context_trace(spu_get_idle__found, ctx, spu);
         spu_init_channels(spu);
         return spu;
 }
@@ -587,6 +591,8 @@ static struct spu *find_victim(struct spu_context *ctx)
         struct spu *spu;
         int node, n;
 
+        spu_context_nospu_trace(spu_find_vitim__enter, ctx);
+
         /*
          * Look for a possible preemption candidate on the local node first.
          * If there is no candidate look at the other nodes.  This isn't
@@ -640,6 +646,8 @@ static struct spu *find_victim(struct spu_context *ctx)
                                 goto restart;
                         }
 
+                        spu_context_trace(__spu_deactivate__unload, ctx, spu);
+
                         mutex_lock(&cbe_spu_info[node].list_mutex);
                         cbe_spu_info[node].nr_active--;
                         spu_unbind_context(spu, victim);
@@ -822,6 +830,7 @@ static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
  */
 void spu_deactivate(struct spu_context *ctx)
 {
+        spu_context_nospu_trace(spu_deactivate__enter, ctx);
         __spu_deactivate(ctx, 1, MAX_PRIO);
 }
 
@@ -835,6 +844,7 @@ void spu_deactivate(struct spu_context *ctx)
  */
 void spu_yield(struct spu_context *ctx)
 {
+        spu_context_nospu_trace(spu_yield__enter, ctx);
         if (!(ctx->flags & SPU_CREATE_NOSCHED)) {
                 mutex_lock(&ctx->state_mutex);
                 __spu_deactivate(ctx, 0, MAX_PRIO);
@@ -864,11 +874,15 @@ static noinline void spusched_tick(struct spu_context *ctx)
                 goto out;
 
         spu = ctx->spu;
+
+        spu_context_trace(spusched_tick__preempt, ctx, spu);
+
         new = grab_runnable_context(ctx->prio + 1, spu->node);
         if (new) {
                 spu_unschedule(spu, ctx);
                 spu_add_to_rq(ctx);
         } else {
+                spu_context_nospu_trace(spusched_tick__newslice, ctx);
                 ctx->time_slice++;
         }
 out:
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 0e114038ea6f..795a1b52538b 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -325,4 +325,9 @@ extern void spu_free_lscsa(struct spu_state *csa);
 extern void spuctx_switch_state(struct spu_context *ctx,
                 enum spu_utilization_state new_state);
 
+#define spu_context_trace(name, ctx, spu) \
+        trace_mark(name, "%p %p", ctx, spu);
+#define spu_context_nospu_trace(name, ctx) \
+        trace_mark(name, "%p", ctx);
+
 #endif
diff --git a/arch/powerpc/platforms/cell/spufs/sputrace.c b/arch/powerpc/platforms/cell/spufs/sputrace.c
new file mode 100644
index 000000000000..2b1953f6f12e
--- /dev/null
+++ b/arch/powerpc/platforms/cell/spufs/sputrace.c
@@ -0,0 +1,250 @@
+/*
+ * Copyright (C) 2007 IBM Deutschland Entwicklung GmbH
+ *      Released under GPL v2.
+ *
+ * Partially based on net/ipv4/tcp_probe.c.
+ *
+ * Simple tracing facility for spu contexts.
+ */
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/marker.h>
+#include <linux/proc_fs.h>
+#include <linux/wait.h>
+#include <asm/atomic.h>
+#include <asm/uaccess.h>
+#include "spufs.h"
+
+struct spu_probe {
+        const char *name;
+        const char *format;
+        marker_probe_func *probe_func;
+};
+
+struct sputrace {
+        ktime_t tstamp;
+        int owner_tid; /* owner */
+        int curr_tid;
+        const char *name;
+        int number;
+};
+
+static int bufsize __read_mostly = 16384;
+MODULE_PARM_DESC(bufsize, "Log buffer size (number of records)");
+module_param(bufsize, int, 0);
+
+
+static DEFINE_SPINLOCK(sputrace_lock);
+static DECLARE_WAIT_QUEUE_HEAD(sputrace_wait);
+static ktime_t sputrace_start;
+static unsigned long sputrace_head, sputrace_tail;
+static struct sputrace *sputrace_log;
+
+static int sputrace_used(void)
+{
+        return (sputrace_head - sputrace_tail) % bufsize;
+}
+
+static inline int sputrace_avail(void)
+{
+        return bufsize - sputrace_used();
+}
+
+static int sputrace_sprint(char *tbuf, int n)
+{
+        const struct sputrace *t = sputrace_log + sputrace_tail % bufsize;
+        struct timespec tv =
+                ktime_to_timespec(ktime_sub(t->tstamp, sputrace_start));
+
+        return snprintf(tbuf, n,
+                "[%lu.%09lu] %d: %s (thread = %d, spu = %d)\n",
+                (unsigned long) tv.tv_sec,
+                (unsigned long) tv.tv_nsec,
+                t->owner_tid,
+                t->name,
+                t->curr_tid,
+                t->number);
+}
+
+static ssize_t sputrace_read(struct file *file, char __user *buf,
+                size_t len, loff_t *ppos)
+{
+        int error = 0, cnt = 0;
+
+        if (!buf || len < 0)
+                return -EINVAL;
+
+        while (cnt < len) {
+                char tbuf[128];
+                int width;
+
+                error = wait_event_interruptible(sputrace_wait,
+                                                 sputrace_used() > 0);
+                if (error)
+                        break;
+
+                spin_lock(&sputrace_lock);
+                if (sputrace_head == sputrace_tail) {
+                        spin_unlock(&sputrace_lock);
+                        continue;
+                }
+
+                width = sputrace_sprint(tbuf, sizeof(tbuf));
+                if (width < len)
+                        sputrace_tail = (sputrace_tail + 1) % bufsize;
+                spin_unlock(&sputrace_lock);
+
+                if (width >= len)
+                        break;
+
+                error = copy_to_user(buf + cnt, tbuf, width);
+                if (error)
+                        break;
+                cnt += width;
+        }
+
+        return cnt == 0 ? error : cnt;
+}
+
+static int sputrace_open(struct inode *inode, struct file *file)
+{
+        spin_lock(&sputrace_lock);
+        sputrace_head = sputrace_tail = 0;
+        sputrace_start = ktime_get();
+        spin_unlock(&sputrace_lock);
+
+        return 0;
+}
+
+static const struct file_operations sputrace_fops = {
+        .owner  = THIS_MODULE,
+        .open   = sputrace_open,
+        .read   = sputrace_read,
+};
+
+static void sputrace_log_item(const char *name, struct spu_context *ctx,
+                struct spu *spu)
+{
+        spin_lock(&sputrace_lock);
+        if (sputrace_avail() > 1) {
+                struct sputrace *t = sputrace_log + sputrace_head;
+
+                t->tstamp = ktime_get();
+                t->owner_tid = ctx->tid;
+                t->name = name;
+                t->curr_tid = current->pid;
+                t->number = spu ? spu->number : -1;
+
+                sputrace_head = (sputrace_head + 1) % bufsize;
+        } else {
+                printk(KERN_WARNING
+                       "sputrace: lost samples due to full buffer.\n");
+        }
+        spin_unlock(&sputrace_lock);
+
+        wake_up(&sputrace_wait);
+}
+
+static void spu_context_event(const struct marker *mdata,
+                void *private, const char *format, ...)
+{
+        struct spu_probe *p = mdata->private;
+        va_list ap;
+        struct spu_context *ctx;
+        struct spu *spu;
+
+        va_start(ap, format);
+        ctx = va_arg(ap, struct spu_context *);
+        spu = va_arg(ap, struct spu *);
+
+        sputrace_log_item(p->name, ctx, spu);
+        va_end(ap);
+}
+
+static void spu_context_nospu_event(const struct marker *mdata,
+                void *private, const char *format, ...)
+{
+        struct spu_probe *p = mdata->private;
+        va_list ap;
+        struct spu_context *ctx;
+
+        va_start(ap, format);
+        ctx = va_arg(ap, struct spu_context *);
+
+        sputrace_log_item(p->name, ctx, NULL);
+        va_end(ap);
+}
+
+struct spu_probe spu_probes[] = {
+        { "spu_bind_context__enter", "%p %p", spu_context_event },
+        { "spu_unbind_context__enter", "%p %p", spu_context_event },
+        { "spu_get_idle__enter", "%p", spu_context_nospu_event },
+        { "spu_get_idle__found", "%p %p", spu_context_event },
+        { "spu_get_idle__not_found", "%p", spu_context_nospu_event },
+        { "spu_find_victim__enter", "%p", spu_context_nospu_event },
+        { "spusched_tick__preempt", "%p %p", spu_context_event },
+        { "spusched_tick__newslice", "%p", spu_context_nospu_event },
+        { "spu_yield__enter", "%p", spu_context_nospu_event },
+        { "spu_deactivate__enter", "%p", spu_context_nospu_event },
+        { "__spu_deactivate__unload", "%p %p", spu_context_event },
+        { "spufs_ps_nopfn__enter", "%p", spu_context_nospu_event },
+        { "spufs_ps_nopfn__sleep", "%p", spu_context_nospu_event },
+        { "spufs_ps_nopfn__wake", "%p %p", spu_context_event },
+        { "spufs_ps_nopfn__insert", "%p %p", spu_context_event },
+        { "spu_acquire_saved__enter", "%p", spu_context_nospu_event },
+        { "destroy_spu_context__enter", "%p", spu_context_nospu_event },
+};
+
+static int __init sputrace_init(void)
+{
+        struct proc_dir_entry *entry;
+        int i, error = -ENOMEM;
+
+        sputrace_log = kcalloc(sizeof(struct sputrace),
+                                bufsize, GFP_KERNEL);
+        if (!sputrace_log)
+                goto out;
+
+        entry = create_proc_entry("sputrace", S_IRUSR, NULL);
+        if (!entry)
+                goto out_free_log;
+        entry->proc_fops = &sputrace_fops;
+
+        for (i = 0; i < ARRAY_SIZE(spu_probes); i++) {
+                struct spu_probe *p = &spu_probes[i];
+
+                error = marker_probe_register(p->name, p->format,
+                                              p->probe_func, p);
+                if (error)
+                        printk(KERN_INFO "Unable to register probe %s\n",
+                                        p->name);
+
+                error = marker_arm(p->name);
+                if (error)
+                        printk(KERN_INFO "Unable to arm probe %s\n", p->name);
+        }
+
+        return 0;
+
+out_free_log:
+        kfree(sputrace_log);
+out:
+        return -ENOMEM;
+}
+
+static void __exit sputrace_exit(void)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(spu_probes); i++)
+                marker_probe_unregister(spu_probes[i].name);
+
+        remove_proc_entry("sputrace", NULL);
+        kfree(sputrace_log);
+}
+
+module_init(sputrace_init);
+module_exit(sputrace_exit);
+
+MODULE_LICENSE("GPL");