X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fring_buffer_frontend.c;h=90c665d6e7104c186cfe12ef63bdd399b13ba16e;hb=8ed66080397eac7fe638dac8a2fd3fcaefd83988;hp=0d8279bb293d07331b36848f54e4315e063cf7e7;hpb=a8f2d0c75c9cc179fc9e7f7ca17ea3b3b3b5af41;p=lttng-modules.git diff --git a/lib/ringbuffer/ring_buffer_frontend.c b/lib/ringbuffer/ring_buffer_frontend.c index 0d8279bb..90c665d6 100644 --- a/lib/ringbuffer/ring_buffer_frontend.c +++ b/lib/ringbuffer/ring_buffer_frontend.c @@ -1,23 +1,9 @@ -/* +/* SPDX-License-Identifier: (GPL-2.0 OR LGPL-2.1) + * * ring_buffer_frontend.c * * Copyright (C) 2005-2012 Mathieu Desnoyers * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation; only - * version 2.1 of the License. - * - * This library is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public - * License along with this library; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - * - * * Ring buffer wait-free buffer synchronization. Producer-consumer and flight * recorder (overwrite) modes. See thesis: * @@ -150,6 +136,7 @@ void lib_ring_buffer_free(struct lib_ring_buffer *buf) lib_ring_buffer_print_errors(chan, buf, buf->backend.cpu); lttng_kvfree(buf->commit_hot); lttng_kvfree(buf->commit_cold); + lttng_kvfree(buf->ts_end); lib_ring_buffer_backend_free(&buf->backend); } @@ -179,6 +166,7 @@ void lib_ring_buffer_reset(struct lib_ring_buffer *buf) v_set(config, &buf->commit_hot[i].cc, 0); v_set(config, &buf->commit_hot[i].seq, 0); v_set(config, &buf->commit_cold[i].cc_sb, 0); + buf->ts_end[i] = 0; } atomic_long_set(&buf->consumed, 0); atomic_set(&buf->record_disabled, 0); @@ -267,6 +255,17 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf, goto free_commit; } + buf->ts_end = + lttng_kvzalloc_node(ALIGN(sizeof(*buf->ts_end) + * chan->backend.num_subbuf, + 1 << INTERNODE_CACHE_SHIFT), + GFP_KERNEL | __GFP_NOWARN, + cpu_to_node(max(cpu, 0))); + if (!buf->ts_end) { + ret = -ENOMEM; + goto free_commit_cold; + } + init_waitqueue_head(&buf->read_wait); init_waitqueue_head(&buf->write_wait); raw_spin_lock_init(&buf->raw_tick_nohz_spinlock); @@ -306,6 +305,8 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf, /* Error handling */ free_init: + lttng_kvfree(buf->ts_end); +free_commit_cold: lttng_kvfree(buf->commit_cold); free_commit: lttng_kvfree(buf->commit_hot); @@ -406,7 +407,7 @@ static void lib_ring_buffer_start_read_timer(struct lib_ring_buffer *buf) { struct channel *chan = buf->backend.chan; const struct lib_ring_buffer_config *config = &chan->backend.config; - unsigned int flags; + unsigned int flags = 0; if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER || !chan->read_timer_interval @@ -1596,14 +1597,26 @@ void lib_ring_buffer_switch_old_end(struct lib_ring_buffer *buf, unsigned long oldidx = subbuf_index(offsets->old - 1, chan); unsigned long commit_count, padding_size, data_size; struct commit_counters_hot *cc_hot; + u64 *ts_end; data_size = subbuf_offset(offsets->old - 1, chan) + 1; padding_size = chan->backend.subbuf_size - data_size; subbuffer_set_data_size(config, &buf->backend, oldidx, data_size); + ts_end = &buf->ts_end[oldidx]; /* - * Order all writes to buffer before the commit count update that will - * determine that the subbuffer is full. + * This is the last space reservation in that sub-buffer before + * it gets delivered. This provides exclusive access to write to + * this sub-buffer's ts_end. There are also no concurrent + * readers of that ts_end because delivery of that sub-buffer is + * postponed until the commit counter is incremented for the + * current space reservation. + */ + *ts_end = tsc; + + /* + * Order all writes to buffer and store to ts_end before the commit + * count update that will determine that the subbuffer is full. */ if (config->ipi == RING_BUFFER_IPI_BARRIER) { /* @@ -1684,10 +1697,21 @@ void lib_ring_buffer_switch_new_end(struct lib_ring_buffer *buf, { const struct lib_ring_buffer_config *config = &chan->backend.config; unsigned long endidx, data_size; + u64 *ts_end; endidx = subbuf_index(offsets->end - 1, chan); data_size = subbuf_offset(offsets->end - 1, chan) + 1; subbuffer_set_data_size(config, &buf->backend, endidx, data_size); + ts_end = &buf->ts_end[endidx]; + /* + * This is the last space reservation in that sub-buffer before + * it gets delivered. This provides exclusive access to write to + * this sub-buffer's ts_end. There are also no concurrent + * readers of that ts_end because delivery of that sub-buffer is + * postponed until the commit counter is incremented for the + * current space reservation. + */ + *ts_end = tsc; } /* @@ -2251,14 +2275,24 @@ void lib_ring_buffer_check_deliver_slow(const struct lib_ring_buffer_config *con if (likely(v_cmpxchg(config, &buf->commit_cold[idx].cc_sb, old_commit_count, old_commit_count + 1) == old_commit_count)) { + u64 *ts_end; + /* * Start of exclusive subbuffer access. We are * guaranteed to be the last writer in this subbuffer * and any other writer trying to access this subbuffer * in this state is required to drop records. + * + * We can read the ts_end for the current sub-buffer + * which has been saved by the very last space + * reservation for the current sub-buffer. + * + * Order increment of commit counter before reading ts_end. */ + smp_mb(); + ts_end = &buf->ts_end[idx]; deliver_count_events(config, buf, idx); - config->cb.buffer_end(buf, tsc, idx, + config->cb.buffer_end(buf, *ts_end, idx, lib_ring_buffer_get_data_size(config, buf, idx));