/*
* Copyright (c) 2016-2019 Cisco and/or its affiliates.
+ * Copyright (c) 2019 Arm Limited
+ * Copyright (c) 2010-2017 Intel Corporation and/or its affiliates.
+ * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
+ * Inspired from DPDK rte_ring.h (SPSC only) (derived from freebsd bufring.h).
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
#include <vppinfra/cpu.h>
static inline u8
-position_lt (svm_fifo_t * f, u32 a, u32 b)
+position_lt (svm_fifo_t * f, u32 a, u32 b, u32 tail)
{
- return (ooo_segment_distance_from_tail (f, a)
- < ooo_segment_distance_from_tail (f, b));
+ return (ooo_segment_distance_from_tail (f, a, tail)
+ < ooo_segment_distance_from_tail (f, b, tail));
}
static inline u8
-position_leq (svm_fifo_t * f, u32 a, u32 b)
+position_leq (svm_fifo_t * f, u32 a, u32 b, u32 tail)
{
- return (ooo_segment_distance_from_tail (f, a)
- <= ooo_segment_distance_from_tail (f, b));
+ return (ooo_segment_distance_from_tail (f, a, tail)
+ <= ooo_segment_distance_from_tail (f, b, tail));
}
static inline u8
-position_gt (svm_fifo_t * f, u32 a, u32 b)
+position_gt (svm_fifo_t * f, u32 a, u32 b, u32 tail)
{
- return (ooo_segment_distance_from_tail (f, a)
- > ooo_segment_distance_from_tail (f, b));
+ return (ooo_segment_distance_from_tail (f, a, tail)
+ > ooo_segment_distance_from_tail (f, b, tail));
}
static inline u32
-position_diff (svm_fifo_t * f, u32 posa, u32 posb)
+position_diff (svm_fifo_t * f, u32 posa, u32 posb, u32 tail)
{
- return ooo_segment_distance_from_tail (f, posa)
- - ooo_segment_distance_from_tail (f, posb);
+ return ooo_segment_distance_from_tail (f, posa, tail)
+ - ooo_segment_distance_from_tail (f, posb, tail);
}
static inline u32
ooo_segment_end_pos (svm_fifo_t * f, ooo_segment_t * s)
{
- return (s->start + s->length) % f->nitems;
+ return s->start + s->length;
}
#ifndef CLIB_MARCH_VARIANT
{
svm_fifo_t *f = va_arg (*args, svm_fifo_t *);
ooo_segment_t *seg = va_arg (*args, ooo_segment_t *);
- u32 normalized_start = (seg->start + f->nitems - f->tail) % f->nitems;
+ u32 normalized_start = (seg->start + f->nitems - f->tail) % f->size;
s = format (s, "[%u, %u], len %u, next %d, prev %d", normalized_start,
- (normalized_start + seg->length) % f->nitems, seg->length,
+ (normalized_start + seg->length) % f->size, seg->length,
seg->next, seg->prev);
return s;
}
trace_len = 0;
#endif
- dummy_fifo = svm_fifo_create (f->nitems);
+ dummy_fifo = svm_fifo_create (f->size);
clib_memset (f->data, 0xFF, f->nitems);
vec_validate (data, f->nitems);
{
if (verbose)
s = format (s, "adding [%u, %u]:", trace[i].offset,
- (trace[i].offset +
- trace[i].len) % dummy_fifo->nitems);
+ (trace[i].offset + trace[i].len) % dummy_fifo->size);
svm_fifo_enqueue_with_offset (dummy_fifo, trace[i].offset,
trace[i].len, &data[offset]);
}
indent = format_get_indent (s);
s = format (s, "cursize %u nitems %u has_event %d\n",
- f->cursize, f->nitems, f->has_event);
- s = format (s, "%Uhead %d tail %d segment manager %u\n", format_white_space,
- indent, f->head, f->tail, f->segment_manager);
+ svm_fifo_max_dequeue (f), f->nitems, f->has_event);
+ s = format (s, "%Uhead %u tail %u segment manager %u\n", format_white_space,
+ indent, (f->head % f->size), (f->tail % f->size),
+ f->segment_manager);
if (verbose > 1)
s = format (s, "%Uvpp session %d thread %d app session %d thread %d\n",
return 0;
clib_memset (f, 0, sizeof (*f));
- f->nitems = data_size_in_bytes;
+ f->size = rounded_data_size;
+ /*
+ * usable size of the fifo set to rounded_data_size - 1
+ * to differentiate between free fifo and empty fifo.
+ */
+ f->nitems = f->size - 1;
f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
f->ct_session_index = SVM_FIFO_INVALID_SESSION_INDEX;
f->segment_index = SVM_FIFO_INVALID_INDEX;
* adjacent segments and removing overlapping ones.
*/
static void
-ooo_segment_add (svm_fifo_t * f, u32 offset, u32 length)
+ooo_segment_add (svm_fifo_t * f, u32 offset, u32 head, u32 tail, u32 length)
{
ooo_segment_t *s, *new_s, *prev, *next, *it;
u32 new_index, s_end_pos, s_index;
- u32 normalized_position, normalized_end_position;
+ u32 offset_pos, offset_end_pos;
- ASSERT (offset + length <= ooo_segment_distance_from_tail (f, f->head));
- normalized_position = (f->tail + offset) % f->nitems;
- normalized_end_position = (f->tail + offset + length) % f->nitems;
+ ASSERT (offset + length <= ooo_segment_distance_from_tail (f, head, tail));
+ offset_pos = tail + offset;
+ offset_end_pos = tail + offset + length;
f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
if (f->ooos_list_head == OOO_SEGMENT_INVALID_INDEX)
{
- s = ooo_segment_new (f, normalized_position, length);
+ s = ooo_segment_new (f, offset_pos, length);
f->ooos_list_head = s - f->ooo_segments;
f->ooos_newest = f->ooos_list_head;
return;
/* Find first segment that starts after new segment */
s = pool_elt_at_index (f->ooo_segments, f->ooos_list_head);
while (s->next != OOO_SEGMENT_INVALID_INDEX
- && position_lt (f, s->start, normalized_position))
+ && position_lt (f, s->start, offset_pos, tail))
s = pool_elt_at_index (f->ooo_segments, s->next);
/* If we have a previous and we overlap it, use it as starting point */
prev = ooo_segment_get_prev (f, s);
if (prev
- && position_leq (f, normalized_position, ooo_segment_end_pos (f, prev)))
+ && position_leq (f, offset_pos, ooo_segment_end_pos (f, prev), tail))
{
s = prev;
s_end_pos = ooo_segment_end_pos (f, s);
- /* Since we have previous, normalized start position cannot be smaller
+ /* Since we have previous, offset start position cannot be smaller
* than prev->start. Check tail */
- ASSERT (position_lt (f, s->start, normalized_position));
+ ASSERT (position_lt (f, s->start, offset_pos, tail));
goto check_tail;
}
s_end_pos = ooo_segment_end_pos (f, s);
/* No overlap, add before current segment */
- if (position_lt (f, normalized_end_position, s->start))
+ if (position_lt (f, offset_end_pos, s->start, tail))
{
- new_s = ooo_segment_new (f, normalized_position, length);
+ new_s = ooo_segment_new (f, offset_pos, length);
new_index = new_s - f->ooo_segments;
/* Pool might've moved, get segment again */
return;
}
/* No overlap, add after current segment */
- else if (position_gt (f, normalized_position, s_end_pos))
+ else if (position_gt (f, offset_pos, s_end_pos, tail))
{
- new_s = ooo_segment_new (f, normalized_position, length);
+ new_s = ooo_segment_new (f, offset_pos, length);
new_index = new_s - f->ooo_segments;
/* Pool might've moved, get segment again */
*/
/* Merge at head */
- if (position_lt (f, normalized_position, s->start))
+ if (position_lt (f, offset_pos, s->start, tail))
{
- s->start = normalized_position;
- s->length = position_diff (f, s_end_pos, s->start);
+ s->start = offset_pos;
+ s->length = position_diff (f, s_end_pos, s->start, tail);
f->ooos_newest = s - f->ooo_segments;
}
check_tail:
/* Overlapping tail */
- if (position_gt (f, normalized_end_position, s_end_pos))
+ if (position_gt (f, offset_end_pos, s_end_pos, tail))
{
- s->length = position_diff (f, normalized_end_position, s->start);
+ s->length = position_diff (f, offset_end_pos, s->start, tail);
/* Remove the completely overlapped segments in the tail */
it = ooo_segment_next (f, s);
while (it && position_leq (f, ooo_segment_end_pos (f, it),
- normalized_end_position))
+ offset_end_pos, tail))
{
next = ooo_segment_next (f, it);
ooo_segment_del (f, it - f->ooo_segments);
}
/* If partial overlap with last, merge */
- if (it && position_leq (f, it->start, normalized_end_position))
+ if (it && position_leq (f, it->start, offset_end_pos, tail))
{
s->length = position_diff (f, ooo_segment_end_pos (f, it),
- s->start);
+ s->start, tail);
ooo_segment_del (f, it - f->ooo_segments);
}
f->ooos_newest = s - f->ooo_segments;
* advanced. Returns the number of bytes added to tail.
*/
static int
-ooo_segment_try_collect (svm_fifo_t * f, u32 n_bytes_enqueued)
+ooo_segment_try_collect (svm_fifo_t * f, u32 n_bytes_enqueued, u32 * tail)
{
ooo_segment_t *s;
u32 index, bytes = 0;
i32 diff;
s = pool_elt_at_index (f->ooo_segments, f->ooos_list_head);
- diff = ooo_segment_distance_to_tail (f, s->start);
+ diff = ooo_segment_distance_to_tail (f, s->start, *tail);
ASSERT (diff != n_bytes_enqueued);
if (s->length > diff)
{
bytes = s->length - diff;
- f->tail += bytes;
- f->tail %= f->nitems;
+ *tail = *tail + bytes;
ooo_segment_del (f, index);
break;
}
if (s->next != OOO_SEGMENT_INVALID_INDEX)
{
s = pool_elt_at_index (f->ooo_segments, s->next);
- diff = ooo_segment_distance_to_tail (f, s->start);
+ diff = ooo_segment_distance_to_tail (f, s->start, *tail);
ooo_segment_del (f, index);
}
/* End of search */
const u8 * copy_from_here)
{
u32 total_copy_bytes, first_copy_bytes, second_copy_bytes;
- u32 cursize, nitems;
+ u32 tail, head, free_count, tail_idx;
+
+ f_load_head_tail_prod (f, &head, &tail);
+
+ /* free space in fifo can only increase during enqueue: SPSC */
+ free_count = f_free_count (f, head, tail);
- /* read cursize, which can only increase while we're working */
- cursize = svm_fifo_max_dequeue (f);
f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
- if (PREDICT_FALSE (cursize == f->nitems))
+ if (PREDICT_FALSE (free_count == 0))
return SVM_FIFO_FULL;
- nitems = f->nitems;
+ /* number of bytes we're going to copy */
+ total_copy_bytes = free_count < max_bytes ? free_count : max_bytes;
- /* Number of bytes we're going to copy */
- total_copy_bytes = (nitems - cursize) < max_bytes ?
- (nitems - cursize) : max_bytes;
+ tail_idx = tail % f->size;
if (PREDICT_TRUE (copy_from_here != 0))
{
- /* Number of bytes in first copy segment */
- first_copy_bytes = ((nitems - f->tail) < total_copy_bytes)
- ? (nitems - f->tail) : total_copy_bytes;
-
- clib_memcpy_fast (&f->data[f->tail], copy_from_here, first_copy_bytes);
- f->tail += first_copy_bytes;
- f->tail = (f->tail == nitems) ? 0 : f->tail;
-
- /* Number of bytes in second copy segment, if any */
- second_copy_bytes = total_copy_bytes - first_copy_bytes;
- if (second_copy_bytes)
+ first_copy_bytes = f->size - tail_idx;
+ if (first_copy_bytes < total_copy_bytes)
{
- clib_memcpy_fast (&f->data[f->tail],
+ clib_memcpy_fast (&f->data[tail_idx], copy_from_here,
+ first_copy_bytes);
+ /* number of bytes in second copy segment */
+ second_copy_bytes = total_copy_bytes - first_copy_bytes;
+ /* wrap around */
+ clib_memcpy_fast (&f->data[0],
copy_from_here + first_copy_bytes,
second_copy_bytes);
- f->tail += second_copy_bytes;
- f->tail = (f->tail == nitems) ? 0 : f->tail;
}
+ else
+ {
+ clib_memcpy_fast (&f->data[tail_idx], copy_from_here,
+ total_copy_bytes);
+ }
+ tail += total_copy_bytes;
}
else
{
ASSERT (0);
-
/* Account for a zero-copy enqueue done elsewhere */
- ASSERT (max_bytes <= (nitems - cursize));
- f->tail += max_bytes;
- f->tail = f->tail % nitems;
- total_copy_bytes = max_bytes;
+ tail += max_bytes;
}
- svm_fifo_trace_add (f, f->head, total_copy_bytes, 2);
+ svm_fifo_trace_add (f, head, total_copy_bytes, 2);
- /* Any out-of-order segments to collect? */
+ /* collect out-of-order segments */
if (PREDICT_FALSE (f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX))
- total_copy_bytes += ooo_segment_try_collect (f, total_copy_bytes);
+ total_copy_bytes += ooo_segment_try_collect (f, total_copy_bytes, &tail);
- /* Atomically increase the queue length */
- ASSERT (cursize + total_copy_bytes <= nitems);
- clib_atomic_fetch_add_rel (&f->cursize, total_copy_bytes);
+ ASSERT (total_copy_bytes <= free_count);
- return (total_copy_bytes);
+ /* store-rel: producer owned index (paired with load-acq in consumer) */
+ clib_atomic_store_rel_n (&f->tail, tail);
+
+ return total_copy_bytes;
}
#ifndef CLIB_MARCH_VARIANT
u32 offset, u32 required_bytes, u8 * copy_from_here)
{
u32 total_copy_bytes, first_copy_bytes, second_copy_bytes;
- u32 cursize, nitems, normalized_offset;
+ u32 tail_offset;
+ u32 tail, head, free_count, tail_offset_idx;
- f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
+ f_load_head_tail_prod (f, &head, &tail);
- /* read cursize, which can only increase while we're working */
- cursize = svm_fifo_max_dequeue (f);
- nitems = f->nitems;
+ /* free space in fifo can only increase during enqueue: SPSC */
+ free_count = f_free_count (f, head, tail);
- ASSERT (required_bytes < nitems);
+ /* will this request fit? */
+ if ((required_bytes + offset) > free_count)
+ return -1;
- normalized_offset = (f->tail + offset) % nitems;
+ f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
- /* Will this request fit? */
- if ((required_bytes + offset) > (nitems - cursize))
- return -1;
+ ASSERT (required_bytes < f->nitems);
+
+ tail_offset = tail + offset;
+ tail_offset_idx = tail_offset % f->size;
svm_fifo_trace_add (f, offset, required_bytes, 1);
- ooo_segment_add (f, offset, required_bytes);
+ ooo_segment_add (f, offset, head, tail, required_bytes);
- /* Number of bytes we're going to copy */
+ /* number of bytes we're going to copy */
total_copy_bytes = required_bytes;
- /* Number of bytes in first copy segment */
- first_copy_bytes = ((nitems - normalized_offset) < total_copy_bytes)
- ? (nitems - normalized_offset) : total_copy_bytes;
-
- clib_memcpy_fast (&f->data[normalized_offset], copy_from_here,
- first_copy_bytes);
+ /* number of bytes in first copy segment */
+ first_copy_bytes = f->size - tail_offset_idx;
- /* Number of bytes in second copy segment, if any */
- second_copy_bytes = total_copy_bytes - first_copy_bytes;
- if (second_copy_bytes)
+ if (first_copy_bytes < total_copy_bytes)
{
- normalized_offset += first_copy_bytes;
- normalized_offset %= nitems;
+ clib_memcpy_fast (&f->data[tail_offset_idx], copy_from_here,
+ first_copy_bytes);
- ASSERT (normalized_offset == 0);
-
- clib_memcpy_fast (&f->data[normalized_offset],
+ /* number of bytes in second copy segment */
+ second_copy_bytes = total_copy_bytes - first_copy_bytes;
+ /* wrap around */
+ clib_memcpy_fast (&f->data[0],
copy_from_here + first_copy_bytes, second_copy_bytes);
}
+ else
+ {
+ clib_memcpy_fast (&f->data[tail_offset_idx], copy_from_here,
+ total_copy_bytes);
+ }
- return (0);
+ return 0;
}
#ifndef CLIB_MARCH_VARIANT
svm_fifo_overwrite_head (svm_fifo_t * f, u8 * data, u32 len)
{
u32 first_chunk;
- first_chunk = f->nitems - f->head;
+ u32 head, tail, head_idx;
+
+ f_load_head_tail_cons (f, &head, &tail);
+ head_idx = head % f->size;
+ first_chunk = f->size - (head_idx);
ASSERT (len <= f->nitems);
if (len <= first_chunk)
- clib_memcpy_fast (&f->data[f->head], data, len);
+ clib_memcpy_fast (&f->data[head_idx], data, len);
else
{
- clib_memcpy_fast (&f->data[f->head], data, first_chunk);
+ clib_memcpy_fast (&f->data[head_idx], data, first_chunk);
clib_memcpy_fast (&f->data[0], data + first_chunk, len - first_chunk);
}
}
u8 * copy_here)
{
u32 total_copy_bytes, first_copy_bytes, second_copy_bytes;
- u32 cursize, nitems;
+ u32 tail, head, cursize, head_idx;
+
+ f_load_head_tail_cons (f, &head, &tail);
+
+ /* current size of fifo can only increase during dequeue: SPSC */
+ cursize = f_cursize (f, head, tail);
- /* read cursize, which can only increase while we're working */
- cursize = svm_fifo_max_dequeue (f);
if (PREDICT_FALSE (cursize == 0))
return -2; /* nothing in the fifo */
- nitems = f->nitems;
-
- /* Number of bytes we're going to copy */
+ /* number of bytes we're going to copy */
total_copy_bytes = (cursize < max_bytes) ? cursize : max_bytes;
+ head_idx = head % f->size;
+
if (PREDICT_TRUE (copy_here != 0))
{
- /* Number of bytes in first copy segment */
- first_copy_bytes = ((nitems - f->head) < total_copy_bytes)
- ? (nitems - f->head) : total_copy_bytes;
- clib_memcpy_fast (copy_here, &f->data[f->head], first_copy_bytes);
- f->head += first_copy_bytes;
- f->head = (f->head == nitems) ? 0 : f->head;
-
- /* Number of bytes in second copy segment, if any */
- second_copy_bytes = total_copy_bytes - first_copy_bytes;
- if (second_copy_bytes)
+ /* number of bytes in first copy segment */
+ first_copy_bytes = f->size - head_idx;
+ if (first_copy_bytes < total_copy_bytes)
{
+ clib_memcpy_fast (copy_here, &f->data[head_idx], first_copy_bytes);
+ /* number of bytes in second copy segment */
+ second_copy_bytes = total_copy_bytes - first_copy_bytes;
+ /* wrap around */
clib_memcpy_fast (copy_here + first_copy_bytes,
- &f->data[f->head], second_copy_bytes);
- f->head += second_copy_bytes;
- f->head = (f->head == nitems) ? 0 : f->head;
+ &f->data[0], second_copy_bytes);
+ }
+ else
+ {
+ clib_memcpy_fast (copy_here, &f->data[head_idx], total_copy_bytes);
}
+ head += total_copy_bytes;
}
else
{
ASSERT (0);
/* Account for a zero-copy dequeue done elsewhere */
- ASSERT (max_bytes <= cursize);
- f->head += max_bytes;
- f->head = f->head % nitems;
- cursize -= max_bytes;
- total_copy_bytes = max_bytes;
+ head += max_bytes;
}
- ASSERT (f->head <= nitems);
ASSERT (cursize >= total_copy_bytes);
- clib_atomic_fetch_sub_rel (&f->cursize, total_copy_bytes);
+ /* store-rel: consumer owned index (paired with load-acq in producer) */
+ clib_atomic_store_rel_n (&f->head, head);
- return (total_copy_bytes);
+ return total_copy_bytes;
}
#ifndef CLIB_MARCH_VARIANT
u32 max_bytes, u8 * copy_here)
{
u32 total_copy_bytes, first_copy_bytes, second_copy_bytes;
- u32 cursize, nitems, real_head;
+ u32 tail, head, cursize;
+ u32 relative_head_idx;
+
+ f_load_head_tail_cons (f, &head, &tail);
+
+ /* current size of fifo can only increase during peek: SPSC */
+ cursize = f_cursize (f, head, tail);
- /* read cursize, which can only increase while we're working */
- cursize = svm_fifo_max_dequeue (f);
if (PREDICT_FALSE (cursize < relative_offset))
return -2; /* nothing in the fifo */
- nitems = f->nitems;
- real_head = f->head + relative_offset;
- real_head = real_head >= nitems ? real_head - nitems : real_head;
+ relative_head_idx = (head + relative_offset) % f->size;
- /* Number of bytes we're going to copy */
- total_copy_bytes = (cursize - relative_offset < max_bytes) ?
+ /* number of bytes we're going to copy */
+ total_copy_bytes = ((cursize - relative_offset) < max_bytes) ?
cursize - relative_offset : max_bytes;
if (PREDICT_TRUE (copy_here != 0))
{
- /* Number of bytes in first copy segment */
- first_copy_bytes =
- ((nitems - real_head) < total_copy_bytes) ?
- (nitems - real_head) : total_copy_bytes;
- clib_memcpy_fast (copy_here, &f->data[real_head], first_copy_bytes);
-
- /* Number of bytes in second copy segment, if any */
- second_copy_bytes = total_copy_bytes - first_copy_bytes;
- if (second_copy_bytes)
+ /* number of bytes in first copy segment */
+ first_copy_bytes = f->size - relative_head_idx;
+ if (first_copy_bytes < total_copy_bytes)
{
+ clib_memcpy_fast (copy_here, &f->data[relative_head_idx],
+ first_copy_bytes);
+
+ /* number of bytes in second copy segment */
+ second_copy_bytes = total_copy_bytes - first_copy_bytes;
clib_memcpy_fast (copy_here + first_copy_bytes, &f->data[0],
second_copy_bytes);
}
+ else
+ {
+ clib_memcpy_fast (copy_here, &f->data[relative_head_idx],
+ total_copy_bytes);
+ }
}
return total_copy_bytes;
}
int
svm_fifo_dequeue_drop (svm_fifo_t * f, u32 max_bytes)
{
- u32 total_drop_bytes, first_drop_bytes, second_drop_bytes;
- u32 cursize, nitems;
+ u32 total_drop_bytes;
+ u32 tail, head, cursize;
+
+ f_load_head_tail_cons (f, &head, &tail);
+
+ /* number of bytes we're going to drop */
+ cursize = f_cursize (f, head, tail);
- /* read cursize, which can only increase while we're working */
- cursize = svm_fifo_max_dequeue (f);
if (PREDICT_FALSE (cursize == 0))
return -2; /* nothing in the fifo */
- nitems = f->nitems;
+ svm_fifo_trace_add (f, tail, total_drop_bytes, 3);
- /* Number of bytes we're going to drop */
+ /* number of bytes we're going to drop */
total_drop_bytes = (cursize < max_bytes) ? cursize : max_bytes;
- svm_fifo_trace_add (f, f->tail, total_drop_bytes, 3);
-
- /* Number of bytes in first copy segment */
- first_drop_bytes =
- ((nitems - f->head) < total_drop_bytes) ?
- (nitems - f->head) : total_drop_bytes;
- f->head += first_drop_bytes;
- f->head = (f->head == nitems) ? 0 : f->head;
-
- /* Number of bytes in second drop segment, if any */
- second_drop_bytes = total_drop_bytes - first_drop_bytes;
- if (second_drop_bytes)
- {
- f->head += second_drop_bytes;
- f->head = (f->head == nitems) ? 0 : f->head;
- }
+ /* move head */
+ head += total_drop_bytes;
- ASSERT (f->head <= nitems);
ASSERT (cursize >= total_drop_bytes);
- clib_atomic_fetch_sub_rel (&f->cursize, total_drop_bytes);
+ /* store-rel: consumer owned index (paired with load-acq in producer) */
+ clib_atomic_store_rel_n (&f->head, head);
return total_drop_bytes;
}
void
svm_fifo_dequeue_drop_all (svm_fifo_t * f)
{
- f->head = f->tail;
- clib_atomic_fetch_sub_rel (&f->cursize, f->cursize);
+ /* consumer foreign index */
+ u32 tail = clib_atomic_load_acq_n (&f->tail);
+ /* store-rel: consumer owned index (paired with load-acq in producer) */
+ clib_atomic_store_rel_n (&f->head, tail);
}
int
svm_fifo_segments (svm_fifo_t * f, svm_fifo_segment_t * fs)
{
- u32 cursize, nitems;
+ u32 cursize, head, tail, head_idx;
- /* read cursize, which can only increase while we're working */
- cursize = svm_fifo_max_dequeue (f);
- if (PREDICT_FALSE (cursize == 0))
- return -2;
+ f_load_head_tail_cons (f, &head, &tail);
+
+ /* consumer function, cursize can only increase while we're working */
+ cursize = f_cursize (f, head, tail);
- nitems = f->nitems;
+ if (PREDICT_FALSE (cursize == 0))
+ return -2; /* nothing in the fifo */
- fs[0].len = ((nitems - f->head) < cursize) ? (nitems - f->head) : cursize;
- fs[0].data = f->data + f->head;
+ head_idx = head % f->size;
- if (fs[0].len < cursize)
+ if (tail < head)
{
+ fs[0].len = f->size - head_idx;
+ fs[0].data = f->data + head_idx;
fs[1].len = cursize - fs[0].len;
fs[1].data = f->data;
}
else
{
+ fs[0].len = cursize;
+ fs[0].data = f->data + head_idx;
fs[1].len = 0;
fs[1].data = 0;
}
void
svm_fifo_segments_free (svm_fifo_t * f, svm_fifo_segment_t * fs)
{
- u32 total_drop_bytes;
+ u32 head, head_idx;
- ASSERT (fs[0].data == f->data + f->head);
- if (fs[1].len)
- {
- f->head = fs[1].len;
- total_drop_bytes = fs[0].len + fs[1].len;
- }
- else
- {
- f->head = (f->head + fs[0].len) % f->nitems;
- total_drop_bytes = fs[0].len;
- }
- clib_atomic_fetch_sub_rel (&f->cursize, total_drop_bytes);
+ /* consumer owned index */
+ head = f->head;
+ head_idx = head % f->size;
+
+ ASSERT (fs[0].data == f->data + head_idx);
+ head += fs[0].len + fs[1].len;
+ /* store-rel: consumer owned index (paired with load-acq in producer) */
+ clib_atomic_store_rel_n (&f->head, head);
+}
+
+/* Assumption: no prod and cons are accessing either dest or src fifo */
+void
+svm_fifo_clone (svm_fifo_t * df, svm_fifo_t * sf)
+{
+ u32 head, tail;
+ clib_memcpy_fast (df->data, sf->data, sf->size);
+
+ f_load_head_tail_all_acq (sf, &head, &tail);
+ clib_atomic_store_rel_n (&df->head, head);
+ clib_atomic_store_rel_n (&df->tail, tail);
}
u32
void
svm_fifo_init_pointers (svm_fifo_t * f, u32 pointer)
{
- f->head = f->tail = pointer % f->nitems;
+ clib_atomic_store_rel_n (&f->head, pointer);
+ clib_atomic_store_rel_n (&f->tail, pointer);
}
void
/*
* Copyright (c) 2016-2019 Cisco and/or its affiliates.
+ * Copyright (c) 2019 Arm Limited
+ * Copyright (c) 2010-2017 Intel Corporation and/or its affiliates.
+ * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
+ * Inspired from DPDK rte_ring.h (SPSC only) (derived from freebsd bufring.h).
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
typedef struct _svm_fifo
{
CLIB_CACHE_LINE_ALIGN_MARK (shared_first);
- volatile u32 cursize; /**< current fifo size */
- u32 nitems;
+ u32 size; /**< size of the fifo(must be power of 2) */
+ u32 nitems; /**< usable size(size-1) */
CLIB_CACHE_LINE_ALIGN_MARK (shared_second);
volatile u32 has_event; /**< non-zero if deq event exists */
u8 *svm_fifo_dump_trace (u8 * s, svm_fifo_t * f);
u8 *svm_fifo_replay (u8 * s, svm_fifo_t * f, u8 no_read, u8 verbose);
+/* internal function */
+static inline void
+f_load_head_tail_cons (svm_fifo_t * f, u32 * head, u32 * tail)
+{
+ /* load-relaxed: consumer owned index */
+ *head = f->head;
+ /* load-acq: consumer foreign index (paired with store-rel in producer) */
+ *tail = clib_atomic_load_acq_n (&f->tail);
+}
+
+/* internal function */
+static inline void
+f_load_head_tail_prod (svm_fifo_t * f, u32 * head, u32 * tail)
+{
+ /* load relaxed: producer owned index */
+ *tail = f->tail;
+ /* load-acq: producer foreign index (paired with store-rel in consumer) */
+ *head = clib_atomic_load_acq_n (&f->head);
+}
+
+/* producer consumer role independent */
+/* internal function */
+static inline void
+f_load_head_tail_all_acq (svm_fifo_t * f, u32 * head, u32 * tail)
+{
+ /* load-acq : consumer foreign index (paired with store-rel) */
+ *tail = clib_atomic_load_acq_n (&f->tail);
+ /* load-acq : producer foriegn index (paired with store-rel) */
+ *head = clib_atomic_load_acq_n (&f->head);
+}
+
+/* internal function */
+static inline u32
+f_free_count (svm_fifo_t * f, u32 head, u32 tail)
+{
+ return (f->nitems + head - tail);
+}
+
+/* internal function */
+static inline u32
+f_cursize (svm_fifo_t * f, u32 head, u32 tail)
+{
+ return (f->nitems - f_free_count (f, head, tail));
+}
+
+/* used by consumer */
+static inline u32
+svm_fifo_max_dequeue_cons (svm_fifo_t * f)
+{
+ u32 tail, head;
+ f_load_head_tail_cons (f, &head, &tail);
+ return f_cursize (f, head, tail);
+}
+
+/* used by producer*/
+static inline u32
+svm_fifo_max_dequeue_prod (svm_fifo_t * f)
+{
+ u32 tail, head;
+ f_load_head_tail_prod (f, &head, &tail);
+ return f_cursize (f, head, tail);
+}
+
+/* use producer or consumer specific functions for perfomance.
+ * svm_fifo_max_dequeue_cons (svm_fifo_t *f)
+ * svm_fifo_max_dequeue_prod (svm_fifo_t *f)
+ */
static inline u32
svm_fifo_max_dequeue (svm_fifo_t * f)
{
- return clib_atomic_load_acq_n (&f->cursize);
+ u32 tail, head;
+ f_load_head_tail_all_acq (f, &head, &tail);
+ return f_cursize (f, head, tail);
}
+/* used by producer */
+static inline int
+svm_fifo_is_full_prod (svm_fifo_t * f)
+{
+ return (svm_fifo_max_dequeue_prod (f) == f->nitems);
+}
+
+/* use producer or consumer specific functions for perfomance.
+ * svm_fifo_is_full_prod (svm_fifo_t * f)
+ * add cons version if needed
+ */
static inline int
svm_fifo_is_full (svm_fifo_t * f)
{
- return (clib_atomic_load_acq_n (&f->cursize) == f->nitems);
+ return (svm_fifo_max_dequeue (f) == f->nitems);
+}
+
+/* used by consumer */
+static inline int
+svm_fifo_is_empty_cons (svm_fifo_t * f)
+{
+ return (svm_fifo_max_dequeue_cons (f) == 0);
}
+/* used by producer */
+static inline int
+svm_fifo_is_empty_prod (svm_fifo_t * f)
+{
+ return (svm_fifo_max_dequeue_prod (f) == 0);
+}
+
+/* use producer or consumer specific functions for perfomance.
+ * svm_fifo_is_empty_cons (svm_fifo_t * f)
+ * svm_fifo_is_empty_prod (svm_fifo_t * f)
+ */
static inline int
svm_fifo_is_empty (svm_fifo_t * f)
{
- return (clib_atomic_load_acq_n (&f->cursize) == 0);
+ return (svm_fifo_max_dequeue (f) == 0);
}
+/* used by producer*/
+static inline u32
+svm_fifo_max_enqueue_prod (svm_fifo_t * f)
+{
+ u32 head, tail;
+ f_load_head_tail_prod (f, &head, &tail);
+ return f_free_count (f, head, tail);
+}
+
+/* use producer or consumer specfic functions for perfomance.
+ * svm_fifo_max_enqueue_prod (svm_fifo_t *f)
+ * add consumer specific version if needed.
+ */
static inline u32
svm_fifo_max_enqueue (svm_fifo_t * f)
{
- return f->nitems - svm_fifo_max_dequeue (f);
+ u32 head, tail;
+ f_load_head_tail_all_acq (f, &head, &tail);
+ return f_free_count (f, head, tail);
}
static inline int
/**
* Sets fifo event flag.
*
- * Also acts as a release barrier.
+ * Also acts as a release ordering.
*
* @return 1 if flag was not set.
*/
int svm_fifo_segments (svm_fifo_t * f, svm_fifo_segment_t * fs);
void svm_fifo_segments_free (svm_fifo_t * f, svm_fifo_segment_t * fs);
void svm_fifo_init_pointers (svm_fifo_t * f, u32 pointer);
+void svm_fifo_clone (svm_fifo_t * df, svm_fifo_t * sf);
void svm_fifo_overwrite_head (svm_fifo_t * f, u8 * data, u32 len);
void svm_fifo_add_subscriber (svm_fifo_t * f, u8 subscriber);
void svm_fifo_del_subscriber (svm_fifo_t * f, u8 subscriber);
always_inline u32
svm_fifo_max_read_chunk (svm_fifo_t * f)
{
- return ((f->tail > f->head) ? (f->tail - f->head) : (f->nitems - f->head));
+ u32 head, tail;
+ u32 head_idx, tail_idx;
+ f_load_head_tail_cons (f, &head, &tail);
+ head_idx = head % f->size;
+ tail_idx = tail % f->size;
+ return tail_idx > head_idx ? (tail_idx - head_idx) : (f->size - head_idx);
}
/**
always_inline u32
svm_fifo_max_write_chunk (svm_fifo_t * f)
{
- return ((f->tail >= f->head) ? (f->nitems - f->tail) : (f->head - f->tail));
+ u32 head, tail;
+ u32 head_idx, tail_idx;
+ f_load_head_tail_prod (f, &head, &tail);
+ head_idx = head % f->size;
+ tail_idx = tail % f->size;
+ return tail_idx >= head_idx ? (f->size - tail_idx) : (head_idx - tail_idx);
}
/**
always_inline void
svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 bytes)
{
- ASSERT (bytes <= svm_fifo_max_enqueue (f));
- f->tail = (f->tail + bytes) % f->nitems;
- clib_atomic_fetch_add_rel (&f->cursize, bytes);
+ ASSERT (bytes <= svm_fifo_max_enqueue_prod (f));
+ /* load-relaxed: producer owned index */
+ u32 tail = f->tail;
+ tail += bytes;
+ /* store-rel: producer owned index (paired with load-acq in consumer) */
+ clib_atomic_store_rel_n (&f->tail, tail);
}
always_inline u8 *
svm_fifo_head (svm_fifo_t * f)
{
- return (f->data + f->head);
+ /* load-relaxed: consumer owned index */
+ return (f->data + (f->head % f->size));
}
always_inline u8 *
svm_fifo_tail (svm_fifo_t * f)
{
- return (f->data + f->tail);
-}
-
-always_inline u32
-svm_fifo_nitems (svm_fifo_t * f)
-{
- return f->nitems;
+ /* load-relaxed: producer owned index */
+ return (f->data + (f->tail % f->size));
}
static inline void
return 1;
else if (want_ntf & SVM_FIFO_WANT_TX_NOTIF_IF_FULL)
{
- u32 max_deq = svm_fifo_max_dequeue (f);
- u32 nitems = svm_fifo_nitems (f);
+ u32 max_deq = svm_fifo_max_dequeue_cons (f);
+ u32 nitems = f->nitems;
if (!f->has_tx_ntf && max_deq < nitems
&& max_deq + n_last_deq >= nitems)
return 1;
}
always_inline u32
-ooo_segment_distance_from_tail (svm_fifo_t * f, u32 pos)
+ooo_segment_distance_from_tail (svm_fifo_t * f, u32 pos, u32 tail)
{
- /* Ambiguous. Assumption is that ooo segments don't touch tail */
- if (PREDICT_FALSE (pos == f->tail && f->tail == f->head))
- return f->nitems;
-
- return (((f->nitems + pos) - f->tail) % f->nitems);
+ return ((pos - tail) % f->size);
}
always_inline u32
-ooo_segment_distance_to_tail (svm_fifo_t * f, u32 pos)
+ooo_segment_distance_to_tail (svm_fifo_t * f, u32 pos, u32 tail)
{
- return (((f->nitems + f->tail) - pos) % f->nitems);
+ return ((tail - pos) % f->size);
}
always_inline u32
-ooo_segment_offset (svm_fifo_t * f, ooo_segment_t * s)
+ooo_segment_offset_prod (svm_fifo_t * f, ooo_segment_t * s)
{
- return ooo_segment_distance_from_tail (f, s->start);
-}
+ u32 tail;
+ /* load-relaxed: producer owned index */
+ tail = f->tail;
-always_inline u32
-ooo_segment_end_offset (svm_fifo_t * f, ooo_segment_t * s)
-{
- return ooo_segment_distance_from_tail (f, s->start) + s->length;
+ return ooo_segment_distance_from_tail (f, s->start, tail);
}
always_inline u32
Code Review / vpp.git / commitdiff