diff options
| -rw-r--r-- | arch/powerpc/perf/vpa-dtl.c | 131 |
1 files changed, 130 insertions, 1 deletions
diff --git a/arch/powerpc/perf/vpa-dtl.c b/arch/powerpc/perf/vpa-dtl.c index 28e7fc6e7015..ead96af37997 100644 --- a/arch/powerpc/perf/vpa-dtl.c +++ b/arch/powerpc/perf/vpa-dtl.c @@ -85,6 +85,24 @@ struct vpa_pmu_buf { u64 *base; u64 size; u64 head; + /* boot timebase and frequency needs to be saved only at once */ + int boottb_freq_saved; +}; + +/* + * To corelate each DTL entry with other events across CPU's, + * we need to map timebase from "struct dtl_entry" which phyp + * provides with boot timebase. This also needs timebase frequency. + * Formula is: ((timbase from DTL entry - boot time) / frequency) + * + * To match with size of "struct dtl_entry" to ease post processing, + * padded 24 bytes to the structure. + */ +struct boottb_freq { + u64 boot_tb; + u64 tb_freq; + u64 timebase; + u64 padded[3]; }; static DEFINE_PER_CPU(struct vpa_pmu_ctx, vpa_pmu_ctx); @@ -95,12 +113,122 @@ static int dtl_global_refc; static spinlock_t dtl_global_lock = __SPIN_LOCK_UNLOCKED(dtl_global_lock); /* + * Capture DTL data in AUX buffer + */ +static void vpa_dtl_capture_aux(long *n_entries, struct vpa_pmu_buf *buf, + struct vpa_dtl *dtl, int index) +{ + struct dtl_entry *aux_copy_buf = (struct dtl_entry *)buf->base; + + /* + * Copy to AUX buffer from per-thread address + */ + memcpy(aux_copy_buf + buf->head, &dtl->buf[index], *n_entries * sizeof(struct dtl_entry)); + + buf->head += *n_entries; + + return; +} + +/* * Function to dump the dispatch trace log buffer data to the * perf data. + * + * perf_aux_output_begin: This function is called before writing + * to AUX area. This returns the pointer to aux area private structure, + * ie "struct vpa_pmu_buf" here which is set in setup_aux() function. + * The function obtains the output handle (used in perf_aux_output_end). + * when capture completes in vpa_dtl_capture_aux(), call perf_aux_output_end() + * to commit the recorded data. + * + * perf_aux_output_end: This function commits data by adjusting the + * aux_head of "struct perf_buffer". aux_tail will be moved in perf tools + * side when writing the data from aux buffer to perf.data file in disk. + * + * Here in the private aux structure, we maintain head to know where + * to copy data next time in the PMU driver. vpa_pmu_buf->head is moved to + * maintain the aux head for PMU driver. It is responsiblity of PMU + * driver to make sure data is copied between perf_aux_output_begin and + * perf_aux_output_end. + * + * After data is copied in vpa_dtl_capture_aux() function, perf_aux_output_end() + * is called to move the aux->head of "struct perf_buffer" to indicate size of + * data in aux buffer. This will post a PERF_RECORD_AUX into the perf buffer. + * Data will be written to disk only when the allocated buffer is full. + * + * By this approach, all the DTL data will be present as-is in the + * perf.data. The data will be pre-processed in perf tools side when doing + * perf report/perf script and this will avoid time taken to create samples + * in the kernel space. */ static void vpa_dtl_dump_sample_data(struct perf_event *event) { - return; + u64 cur_idx, last_idx, i; + u64 boot_tb; + struct boottb_freq boottb_freq; + + /* actual number of entries read */ + long n_read = 0, read_size = 0; + + /* number of entries added to dtl buffer */ + long n_req; + + struct vpa_pmu_ctx *vpa_ctx = this_cpu_ptr(&vpa_pmu_ctx); + + struct vpa_pmu_buf *aux_buf; + + struct vpa_dtl *dtl = &per_cpu(vpa_dtl_cpu, event->cpu); + + cur_idx = be64_to_cpu(lppaca_of(event->cpu).dtl_idx); + last_idx = dtl->last_idx; + + if (last_idx + N_DISPATCH_LOG <= cur_idx) + last_idx = cur_idx - N_DISPATCH_LOG + 1; + + n_req = cur_idx - last_idx; + + /* no new entry added to the buffer, return */ + if (n_req <= 0) + return; + + dtl->last_idx = last_idx + n_req; + boot_tb = get_boot_tb(); + + i = last_idx % N_DISPATCH_LOG; + + aux_buf = perf_aux_output_begin(&vpa_ctx->handle, event); + if (!aux_buf) { + pr_debug("returning. no aux\n"); + return; + } + + if (!aux_buf->boottb_freq_saved) { + pr_debug("Copying boot tb to aux buffer: %lld\n", boot_tb); + /* Save boot_tb to convert raw timebase to it's relative system boot time */ + boottb_freq.boot_tb = boot_tb; + /* Save tb_ticks_per_sec to convert timebase to sec */ + boottb_freq.tb_freq = tb_ticks_per_sec; + boottb_freq.timebase = 0; + memcpy(aux_buf->base, &boottb_freq, sizeof(boottb_freq)); + aux_buf->head += 1; + aux_buf->boottb_freq_saved = 1; + n_read += 1; + } + + /* read the tail of the buffer if we've wrapped */ + if (i + n_req > N_DISPATCH_LOG) { + read_size = N_DISPATCH_LOG - i; + vpa_dtl_capture_aux(&read_size, aux_buf, dtl, i); + n_req -= read_size; + n_read += read_size; + i = 0; + } + + /* .. and now the head */ + vpa_dtl_capture_aux(&n_req, aux_buf, dtl, i); + + /* Move the aux->head to indicate size of data in aux buffer */ + perf_aux_output_end(&vpa_ctx->handle, (n_req + n_read) * sizeof(struct dtl_entry)); } /* @@ -363,6 +491,7 @@ static void *vpa_dtl_setup_aux(struct perf_event *event, void **pages, buf->size = nr_pages << PAGE_SHIFT; buf->head = 0; + buf->boottb_freq_saved = 0; return no_free_ptr(buf); } |