Fix: sample discarded events count before reserve

[lttng-ust.git] / src / common / ringbuffer / ring_buffer_frontend.c

diff --git a/src/common/ringbuffer/ring_buffer_frontend.c b/src/common/ringbuffer/ring_buffer_frontend.c
index 4d06bf63140c6218c8abf7b278cd3f7b48026194..91c69b7697d9e7f1bd1b06a518a66049a8ce210c 100644 (file)
--- a/src/common/ringbuffer/ring_buffer_frontend.c
+++ b/src/common/ringbuffer/ring_buffer_frontend.c
@@ -1763,7 +1763,7 @@ static
 void lib_ring_buffer_switch_old_start(struct lttng_ust_ring_buffer *buf,
                                      struct lttng_ust_ring_buffer_channel *chan,
                                      struct switch_offsets *offsets,
-                                     uint64_t tsc,
+                                     const struct lttng_ust_ring_buffer_ctx *ctx,
                                      struct lttng_ust_shm_handle *handle)
 {
        const struct lttng_ust_ring_buffer_config *config = &chan->backend.config;
@@ -1771,7 +1771,7 @@ void lib_ring_buffer_switch_old_start(struct lttng_ust_ring_buffer *buf,
        unsigned long commit_count;
        struct commit_counters_hot *cc_hot;
 
-       config->cb.buffer_begin(buf, tsc, oldidx, handle);
+       config->cb.buffer_begin(buf, ctx->priv->tsc, oldidx, handle);
 
        /*
         * Order all writes to buffer before the commit count update that will
@@ -1786,7 +1786,7 @@ void lib_ring_buffer_switch_old_start(struct lttng_ust_ring_buffer *buf,
        commit_count = v_read(config, &cc_hot->cc);
        /* Check if the written buffer has to be delivered */
        lib_ring_buffer_check_deliver(config, buf, chan, offsets->old,
-                                     commit_count, oldidx, handle, tsc);
+                                     commit_count, oldidx, handle, ctx);
        lib_ring_buffer_write_commit_counter(config, buf, chan,
                        offsets->old + config->cb.subbuffer_header_size(),
                        commit_count, handle, cc_hot);
@@ -1804,7 +1804,7 @@ static
 void lib_ring_buffer_switch_old_end(struct lttng_ust_ring_buffer *buf,
                                    struct lttng_ust_ring_buffer_channel *chan,
                                    struct switch_offsets *offsets,
-                                   uint64_t tsc,
+                                   const struct lttng_ust_ring_buffer_ctx *ctx,
                                    struct lttng_ust_shm_handle *handle)
 {
        const struct lttng_ust_ring_buffer_config *config = &chan->backend.config;
@@ -1829,7 +1829,7 @@ void lib_ring_buffer_switch_old_end(struct lttng_ust_ring_buffer *buf,
         * postponed until the commit counter is incremented for the
         * current space reservation.
         */
-       *ts_end = tsc;
+       *ts_end = ctx->priv->tsc;
 
        /*
         * Order all writes to buffer and store to ts_end before the commit
@@ -1842,7 +1842,7 @@ void lib_ring_buffer_switch_old_end(struct lttng_ust_ring_buffer *buf,
        v_add(config, padding_size, &cc_hot->cc);
        commit_count = v_read(config, &cc_hot->cc);
        lib_ring_buffer_check_deliver(config, buf, chan, offsets->old - 1,
-                                     commit_count, oldidx, handle, tsc);
+                                     commit_count, oldidx, handle, ctx);
        lib_ring_buffer_write_commit_counter(config, buf, chan,
                        offsets->old + padding_size, commit_count, handle,
                        cc_hot);
@@ -1859,7 +1859,7 @@ static
 void lib_ring_buffer_switch_new_start(struct lttng_ust_ring_buffer *buf,
                                      struct lttng_ust_ring_buffer_channel *chan,
                                      struct switch_offsets *offsets,
-                                     uint64_t tsc,
+                                     const struct lttng_ust_ring_buffer_ctx *ctx,
                                      struct lttng_ust_shm_handle *handle)
 {
        const struct lttng_ust_ring_buffer_config *config = &chan->backend.config;
@@ -1867,7 +1867,7 @@ void lib_ring_buffer_switch_new_start(struct lttng_ust_ring_buffer *buf,
        unsigned long commit_count;
        struct commit_counters_hot *cc_hot;
 
-       config->cb.buffer_begin(buf, tsc, beginidx, handle);
+       config->cb.buffer_begin(buf, ctx->priv->tsc, beginidx, handle);
 
        /*
         * Order all writes to buffer before the commit count update that will
@@ -1881,7 +1881,7 @@ void lib_ring_buffer_switch_new_start(struct lttng_ust_ring_buffer *buf,
        commit_count = v_read(config, &cc_hot->cc);
        /* Check if the written buffer has to be delivered */
        lib_ring_buffer_check_deliver(config, buf, chan, offsets->begin,
-                                     commit_count, beginidx, handle, tsc);
+                                     commit_count, beginidx, handle, ctx);
        lib_ring_buffer_write_commit_counter(config, buf, chan,
                        offsets->begin + config->cb.subbuffer_header_size(),
                        commit_count, handle, cc_hot);
@@ -1899,7 +1899,7 @@ static
 void lib_ring_buffer_switch_new_end(struct lttng_ust_ring_buffer *buf,
                                    struct lttng_ust_ring_buffer_channel *chan,
                                    struct switch_offsets *offsets,
-                                   uint64_t tsc,
+                                   const struct lttng_ust_ring_buffer_ctx *ctx,
                                    struct lttng_ust_shm_handle *handle)
 {
        const struct lttng_ust_ring_buffer_config *config = &chan->backend.config;
@@ -1921,7 +1921,7 @@ void lib_ring_buffer_switch_new_end(struct lttng_ust_ring_buffer *buf,
         * postponed until the commit counter is incremented for the
         * current space reservation.
         */
-       *ts_end = tsc;
+       *ts_end = ctx->priv->tsc;
 }
 
 /*
@@ -1934,7 +1934,7 @@ int lib_ring_buffer_try_switch_slow(enum switch_mode mode,
                                    struct lttng_ust_ring_buffer *buf,
                                    struct lttng_ust_ring_buffer_channel *chan,
                                    struct switch_offsets *offsets,
-                                   uint64_t *tsc,
+                                   struct lttng_ust_ring_buffer_ctx *ctx,
                                    struct lttng_ust_shm_handle *handle)
 {
        const struct lttng_ust_ring_buffer_config *config = &chan->backend.config;
@@ -1945,7 +1945,7 @@ int lib_ring_buffer_try_switch_slow(enum switch_mode mode,
        offsets->switch_old_start = 0;
        off = subbuf_offset(offsets->begin, chan);
 
-       *tsc = config->cb.ring_buffer_clock_read(chan);
+       ctx->priv->tsc = config->cb.ring_buffer_clock_read(chan);
 
        /*
         * Ensure we flush the header of an empty subbuffer when doing the
@@ -2032,6 +2032,13 @@ int lib_ring_buffer_try_switch_slow(enum switch_mode mode,
        offsets->begin = subbuf_align(offsets->begin, chan);
        /* Note: old points to the next subbuf at offset 0 */
        offsets->end = offsets->begin;
+       /*
+        * Populate the records lost counters prior to performing a
+        * sub-buffer switch.
+        */
+       ctx->priv->records_lost_full = v_read(config, &buf->records_lost_full);
+       ctx->priv->records_lost_wrap = v_read(config, &buf->records_lost_wrap);
+       ctx->priv->records_lost_big = v_read(config, &buf->records_lost_big);
        return 0;
 }
 
@@ -2050,10 +2057,12 @@ void lib_ring_buffer_switch_slow(struct lttng_ust_ring_buffer *buf, enum switch_
 {
        struct lttng_ust_ring_buffer_channel *chan;
        const struct lttng_ust_ring_buffer_config *config;
+       struct lttng_ust_ring_buffer_ctx_private ctx_priv;
+       struct lttng_ust_ring_buffer_ctx ctx;
        struct switch_offsets offsets;
        unsigned long oldidx;
-       uint64_t tsc;
 
+       ctx.priv = &ctx_priv;
        chan = shmp(handle, buf->backend.chan);
        if (!chan)
                return;
@@ -2066,7 +2075,7 @@ void lib_ring_buffer_switch_slow(struct lttng_ust_ring_buffer *buf, enum switch_
         */
        do {
                if (lib_ring_buffer_try_switch_slow(mode, buf, chan, &offsets,
-                                                   &tsc, handle))
+                                                   &ctx, handle))
                        return; /* Switch not needed */
        } while (v_cmpxchg(config, &buf->offset, offsets.old, offsets.end)
                 != offsets.old);
@@ -2077,7 +2086,7 @@ void lib_ring_buffer_switch_slow(struct lttng_ust_ring_buffer *buf, enum switch_
         * records, never the opposite (missing a full TSC record when it would
         * be needed).
         */
-       save_last_tsc(config, buf, tsc);
+       save_last_tsc(config, buf, ctx.priv->tsc);
 
        /*
         * Push the reader if necessary
@@ -2091,14 +2100,14 @@ void lib_ring_buffer_switch_slow(struct lttng_ust_ring_buffer *buf, enum switch_
         * May need to populate header start on SWITCH_FLUSH.
         */
        if (offsets.switch_old_start) {
-               lib_ring_buffer_switch_old_start(buf, chan, &offsets, tsc, handle);
+               lib_ring_buffer_switch_old_start(buf, chan, &offsets, &ctx, handle);
                offsets.old += config->cb.subbuffer_header_size();
        }
 
        /*
         * Switch old subbuffer.
         */
-       lib_ring_buffer_switch_old_end(buf, chan, &offsets, tsc, handle);
+       lib_ring_buffer_switch_old_end(buf, chan, &offsets, &ctx, handle);
 }
 
 static
@@ -2308,6 +2317,15 @@ retry:
                 */
                offsets->switch_new_end = 1;    /* For offsets->begin */
        }
+       /*
+        * Populate the records lost counters when the space reservation
+        * may cause a sub-buffer switch.
+        */
+       if (offsets->switch_new_end || offsets->switch_old_end) {
+               ctx_private->records_lost_full = v_read(config, &buf->records_lost_full);
+               ctx_private->records_lost_wrap = v_read(config, &buf->records_lost_wrap);
+               ctx_private->records_lost_big = v_read(config, &buf->records_lost_big);
+       }
        return 0;
 }
 
@@ -2376,17 +2394,17 @@ int lib_ring_buffer_reserve_slow(struct lttng_ust_ring_buffer_ctx *ctx,
                lib_ring_buffer_clear_noref(config, &buf->backend,
                                            subbuf_index(offsets.old - 1, chan),
                                            handle);
-               lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx_private->tsc, handle);
+               lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx, handle);
        }
 
        /*
         * Populate new subbuffer.
         */
        if (caa_unlikely(offsets.switch_new_start))
-               lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx_private->tsc, handle);
+               lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx, handle);
 
        if (caa_unlikely(offsets.switch_new_end))
-               lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx_private->tsc, handle);
+               lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx, handle);
 
        ctx_private->slot_size = offsets.size;
        ctx_private->pre_offset = offsets.begin;
@@ -2447,7 +2465,7 @@ void lib_ring_buffer_check_deliver_slow(const struct lttng_ust_ring_buffer_confi
                                   unsigned long commit_count,
                                   unsigned long idx,
                                   struct lttng_ust_shm_handle *handle,
-                                  uint64_t tsc __attribute__((unused)))
+                                  const struct lttng_ust_ring_buffer_ctx *ctx)
 {
        unsigned long old_commit_count = commit_count
                                         - chan->backend.subbuf_size;
@@ -2515,7 +2533,7 @@ void lib_ring_buffer_check_deliver_slow(const struct lttng_ust_ring_buffer_confi
                                                                buf,
                                                                idx,
                                                                handle),
-                                     handle);
+                                     handle, ctx);
 
                /*
                 * Increment the packet counter while we have exclusive