From 5158e9b5218bd3799c9fa8c401ad24d7f0c0a0a1 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 29 Apr 2008 17:08:38 +1000 Subject: [PATCH] [POWERPC] spufs: add context switch notification log There are userspace instrumentation tools that need to monitor spu context switches. This patch adds a new file called 'switch_log' to each spufs context directory that can be used to monitor the context switches. Context switch in/out and exit from spu_run are monitored after the file was first opened and can be read from it. Signed-off-by: Christoph Hellwig Signed-off-by: Jeremy Kerr --- arch/powerpc/platforms/cell/spufs/context.c | 1 + arch/powerpc/platforms/cell/spufs/file.c | 166 ++++++++++++++++++++++++++++ arch/powerpc/platforms/cell/spufs/run.c | 2 + arch/powerpc/platforms/cell/spufs/sched.c | 2 + arch/powerpc/platforms/cell/spufs/spufs.h | 29 +++++ 5 files changed, 200 insertions(+) diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c index 0ad83ae..91f2d4d 100644 --- a/arch/powerpc/platforms/cell/spufs/context.c +++ b/arch/powerpc/platforms/cell/spufs/context.c @@ -88,6 +88,7 @@ void destroy_spu_context(struct kref *kref) kref_put(ctx->prof_priv_kref, ctx->prof_priv_release); BUG_ON(!list_empty(&ctx->rq)); atomic_dec(&nr_spu_contexts); + kfree(ctx->switch_log); kfree(ctx); } diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c index ba791e9..b5c1505 100644 --- a/arch/powerpc/platforms/cell/spufs/file.c +++ b/arch/powerpc/platforms/cell/spufs/file.c @@ -2387,6 +2387,171 @@ static const struct file_operations spufs_stat_fops = { .release = single_release, }; +static inline int spufs_switch_log_used(struct spu_context *ctx) +{ + return (ctx->switch_log->head - ctx->switch_log->tail) % + SWITCH_LOG_BUFSIZE; +} + +static inline int spufs_switch_log_avail(struct spu_context *ctx) +{ + return SWITCH_LOG_BUFSIZE - spufs_switch_log_used(ctx); +} + +static int spufs_switch_log_open(struct inode *inode, struct file *file) +{ + struct spu_context *ctx = SPUFS_I(inode)->i_ctx; + + /* + * We (ab-)use the mapping_lock here because it serves the similar + * purpose for synchronizing open/close elsewhere. Maybe it should + * be renamed eventually. + */ + mutex_lock(&ctx->mapping_lock); + if (ctx->switch_log) { + spin_lock(&ctx->switch_log->lock); + ctx->switch_log->head = 0; + ctx->switch_log->tail = 0; + spin_unlock(&ctx->switch_log->lock); + } else { + /* + * We allocate the switch log data structures on first open. + * They will never be free because we assume a context will + * be traced until it goes away. + */ + ctx->switch_log = kzalloc(sizeof(struct switch_log) + + SWITCH_LOG_BUFSIZE * sizeof(struct switch_log_entry), + GFP_KERNEL); + if (!ctx->switch_log) + goto out; + spin_lock_init(&ctx->switch_log->lock); + init_waitqueue_head(&ctx->switch_log->wait); + } + mutex_unlock(&ctx->mapping_lock); + + return 0; + out: + mutex_unlock(&ctx->mapping_lock); + return -ENOMEM; +} + +static int switch_log_sprint(struct spu_context *ctx, char *tbuf, int n) +{ + struct switch_log_entry *p; + + p = ctx->switch_log->log + ctx->switch_log->tail % SWITCH_LOG_BUFSIZE; + + return snprintf(tbuf, n, "%u.%09u %d %u %u %llu\n", + (unsigned int) p->tstamp.tv_sec, + (unsigned int) p->tstamp.tv_nsec, + p->spu_id, + (unsigned int) p->type, + (unsigned int) p->val, + (unsigned long long) p->timebase); +} + +static ssize_t spufs_switch_log_read(struct file *file, char __user *buf, + size_t len, loff_t *ppos) +{ + struct inode *inode = file->f_path.dentry->d_inode; + struct spu_context *ctx = SPUFS_I(inode)->i_ctx; + int error = 0, cnt = 0; + + if (!buf || len < 0) + return -EINVAL; + + while (cnt < len) { + char tbuf[128]; + int width; + + if (file->f_flags & O_NONBLOCK) { + if (spufs_switch_log_used(ctx) <= 0) + return cnt ? cnt : -EAGAIN; + } else { + /* Wait for data in buffer */ + error = wait_event_interruptible(ctx->switch_log->wait, + spufs_switch_log_used(ctx) > 0); + if (error) + break; + } + + spin_lock(&ctx->switch_log->lock); + if (ctx->switch_log->head == ctx->switch_log->tail) { + /* multiple readers race? */ + spin_unlock(&ctx->switch_log->lock); + continue; + } + + width = switch_log_sprint(ctx, tbuf, sizeof(tbuf)); + if (width < len) { + ctx->switch_log->tail = + (ctx->switch_log->tail + 1) % + SWITCH_LOG_BUFSIZE; + } + + spin_unlock(&ctx->switch_log->lock); + + /* + * If the record is greater than space available return + * partial buffer (so far) + */ + if (width >= len) + break; + + error = copy_to_user(buf + cnt, tbuf, width); + if (error) + break; + cnt += width; + } + + return cnt == 0 ? error : cnt; +} + +static unsigned int spufs_switch_log_poll(struct file *file, poll_table *wait) +{ + struct inode *inode = file->f_path.dentry->d_inode; + struct spu_context *ctx = SPUFS_I(inode)->i_ctx; + unsigned int mask = 0; + + poll_wait(file, &ctx->switch_log->wait, wait); + + if (spufs_switch_log_used(ctx) > 0) + mask |= POLLIN; + + return mask; +} + +static const struct file_operations spufs_switch_log_fops = { + .owner = THIS_MODULE, + .open = spufs_switch_log_open, + .read = spufs_switch_log_read, + .poll = spufs_switch_log_poll, +}; + +void spu_switch_log_notify(struct spu *spu, struct spu_context *ctx, + u32 type, u32 val) +{ + if (!ctx->switch_log) + return; + + spin_lock(&ctx->switch_log->lock); + if (spufs_switch_log_avail(ctx) > 1) { + struct switch_log_entry *p; + + p = ctx->switch_log->log + ctx->switch_log->head; + ktime_get_ts(&p->tstamp); + p->timebase = get_tb(); + p->spu_id = spu ? spu->number : -1; + p->type = type; + p->val = val; + + ctx->switch_log->head = + (ctx->switch_log->head + 1) % SWITCH_LOG_BUFSIZE; + } + spin_unlock(&ctx->switch_log->lock); + + wake_up(&ctx->switch_log->wait); +} struct tree_descr spufs_dir_contents[] = { { "capabilities", &spufs_caps_fops, 0444, }, @@ -2423,6 +2588,7 @@ struct tree_descr spufs_dir_contents[] = { { "proxydma_info", &spufs_proxydma_info_fops, 0444, }, { "tid", &spufs_tid_fops, 0444, }, { "stat", &spufs_stat_fops, 0444, }, + { "switch_log", &spufs_switch_log_fops, 0444 }, {}, }; diff --git a/arch/powerpc/platforms/cell/spufs/run.c b/arch/powerpc/platforms/cell/spufs/run.c index 96bf7c2..a9c35b7 100644 --- a/arch/powerpc/platforms/cell/spufs/run.c +++ b/arch/powerpc/platforms/cell/spufs/run.c @@ -405,6 +405,8 @@ long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event) ret = spu_run_fini(ctx, npc, &status); spu_yield(ctx); + spu_switch_log_notify(NULL, ctx, SWITCH_LOG_EXIT, status); + if ((status & SPU_STATUS_STOPPED_BY_STOP) && (((status >> SPU_STOP_STATUS_SHIFT) & 0x3f00) == 0x2100)) ctx->stats.libassist++; diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c index 00528ef..31e9d85 100644 --- a/arch/powerpc/platforms/cell/spufs/sched.c +++ b/arch/powerpc/platforms/cell/spufs/sched.c @@ -240,6 +240,7 @@ static void spu_bind_context(struct spu *spu, struct spu_context *ctx) spu->mfc_callback = spufs_mfc_callback; mb(); spu_unmap_mappings(ctx); + spu_switch_log_notify(spu, ctx, SWITCH_LOG_START, 0); spu_restore(&ctx->csa, spu); spu->timestamp = jiffies; spu_cpu_affinity_set(spu, raw_smp_processor_id()); @@ -419,6 +420,7 @@ static void spu_unbind_context(struct spu *spu, struct spu_context *ctx) spu_switch_notify(spu, NULL); spu_unmap_mappings(ctx); spu_save(&ctx->csa, spu); + spu_switch_log_notify(spu, ctx, SWITCH_LOG_STOP, 0); spu->timestamp = jiffies; ctx->state = SPU_STATE_SAVED; spu->ibox_callback = NULL; diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h index cdc5151..dd63b16 100644 --- a/arch/powerpc/platforms/cell/spufs/spufs.h +++ b/arch/powerpc/platforms/cell/spufs/spufs.h @@ -47,6 +47,30 @@ enum { SPU_SCHED_SPU_RUN, /* context is within spu_run */ }; +enum { + SWITCH_LOG_BUFSIZE = 4096, +}; + +enum { + SWITCH_LOG_START, + SWITCH_LOG_STOP, + SWITCH_LOG_EXIT, +}; + +struct switch_log { + spinlock_t lock; + wait_queue_head_t wait; + unsigned long head; + unsigned long tail; + struct switch_log_entry { + struct timespec tstamp; + s32 spu_id; + u32 type; + u32 val; + u64 timebase; + } log[]; +}; + struct spu_context { struct spu *spu; /* pointer to a physical SPU */ struct spu_state csa; /* SPU context save area. */ @@ -116,6 +140,9 @@ struct spu_context { unsigned long long libassist; } stats; + /* context switch log */ + struct switch_log *switch_log; + struct list_head aff_list; int aff_head; int aff_offset; @@ -256,6 +283,8 @@ int spu_activate(struct spu_context *ctx, unsigned long flags); void spu_deactivate(struct spu_context *ctx); void spu_yield(struct spu_context *ctx); void spu_switch_notify(struct spu *spu, struct spu_context *ctx); +void spu_switch_log_notify(struct spu *spu, struct spu_context *ctx, + u32 type, u32 val); void spu_set_timeslice(struct spu_context *ctx); void spu_update_sched_info(struct spu_context *ctx); void __spu_update_sched_info(struct spu_context *ctx); -- 2.7.4