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clIndexedQueue.cl
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clIndexedQueue.cl
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/**
* clIndexedQueue.cl
* Indexed queue implementation in OpenCL
* Copyright (C) 2013-2014 Roy Spliet, Delft University of Technology
*
* 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; either
* version 2.1 of the License, or (at your option) any later version.
*
* 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
*/
#include "clIndexedQueue.h"
/* Lines get too long... */
#define uptr uintptr_t
#define POISON 1
struct mem_item {
clIndexedQueue_item q;
uint32_t filler;
uintptr_t thisobj;
};
/**
* clIndexedQueue_ptr2idx() - Convert a pointer and tag to an index value
* @q: Indexed queue object
* @ptr: Pointer to convert
* This helper function produces a uint32_t variable with the following bit-layout:
* 0 Poison
* 21:1 Index (base + stride * (n-1)
* 32:22 Tag
*
* Returns 0 on failure.
*/
uint32_t
clIndexedQueue_ptr2idx(clIndexedQueue __global *q, void __global *ptr)
{
uptr idx = (uptr) ptr;
/* Before the base isn't possible */
if(idx < (uptr) q->base)
return 0;
idx -= (uptr) q->base;
/* Does it align to a stride boundary nicely? */
if(idx & ((1 << q->stride) - 1))
return 0;
idx >>= q->stride;
idx++;
/* Does the index still fit? */
if(idx > ((1 << 20) - 1))
return 0;
return (uint32_t) idx << 1;
}
/**
* clIndexedQueue_idx2ptr() - Convert a pointer and tag to an index value
* @q: Indexed queue object
* @idx: Index to convert
*/
inline void __global*
clIndexedQueue_idx2ptr(clIndexedQueue __global *q, uint32_t idx)
{
size_t i = idx;
idx >>= 1;
idx &= 0xfffff;
if(idx == 0)
return 0;
idx--;
i = idx;
i <<= q->stride;
return &q->base[i];
}
#define PTR(i,t) ((i & 0x1fffe) | ((((t)+1) & 0x7ff) << 22))
#define TAG(i) ((i >> 22) & 0x7ff)
#define IDX(i) ((i & 0x1fffe) >> 1)
__kernel void
clIndexedQueue_init(void __global *queue, void __global *base,
uint32_t stride_l2, void __global *i)
{
clIndexedQueue __global *q = (clIndexedQueue __global *) queue;
uint32_t idx, tag;
clIndexedQueue_item __global *item = (clIndexedQueue_item __global *)i;
q->base = base;
q->stride = stride_l2;
tag = TAG(item->next);
item->next = PTR(0, tag);
idx = clIndexedQueue_ptr2idx(q, item);
q->head = PTR(idx, tag);
q->tail = PTR(idx, tag);
mem_fence(CLK_GLOBAL_MEM_FENCE);
}
/**
* idxd_enqueue() - Add an item to the indexed queue
* @q: Queue to add the item to
* @item: Item to add to the queue
* @return 1 iff enqueuing succeeded, 0 otherwise
*/
int
idxd_enqueue(clIndexedQueue __global *q, clIndexedQueue_item __global *item)
{
clIndexedQueue_item __global *tail;
unsigned int ret = 0;
uint32_t idx, tag,
tailidx,
nextidx;
if(item == NULL)
return 0;
tag = TAG(item->next);
item->next = PTR(0, tag-1);
tag++;
idx = clIndexedQueue_ptr2idx(q, item);
while(1) {
tailidx = q->tail;
mem_fence(CLK_GLOBAL_MEM_FENCE);
tail = (clIndexedQueue_item __global *)
clIndexedQueue_idx2ptr(q, tailidx);
nextidx = tail->next;
mem_fence(CLK_GLOBAL_MEM_FENCE);
/* Did I read a consistent state? */
if(q->tail == tailidx) {
if(IDX(nextidx) == 0) {
tag = TAG(nextidx);
if(atom_cmpxchg(&tail->next, nextidx, PTR(idx, tag)) == nextidx) {
mem_fence(CLK_GLOBAL_MEM_FENCE);
ret = 1;
break;
}
} else {
tag = TAG(tailidx);
atom_cmpxchg(&q->tail, tailidx, PTR(nextidx, tag));
mem_fence(CLK_GLOBAL_MEM_FENCE);
}
}
}
tag = TAG(tailidx);
atom_cmpxchg(&q->tail, tailidx, PTR(idx, tag));
mem_fence(CLK_GLOBAL_MEM_FENCE);
return ret;
}
/**
* idxd_dequeue() - Remove and return the next item in the queue
* @q: Queue to get the item from
* @return The next queue item, NULL on failure.
*/
clIndexedQueue_item __global *
idxd_dequeue(clIndexedQueue __global *q)
{
clIndexedQueue_item __global *head;
uint32_t tag,
nextidx,
tailidx,
headidx;
while(1) {
headidx = q->head;
mem_fence(CLK_GLOBAL_MEM_FENCE);
head = (clIndexedQueue_item __global *)
clIndexedQueue_idx2ptr(q, headidx);
tailidx = q->tail;
nextidx = head->next;
mem_fence(CLK_GLOBAL_MEM_FENCE);
if(headidx == q->head) {
if(IDX(headidx) == IDX(tailidx)) {
if(IDX(nextidx) == 0) {
return NULL;
}
tag = TAG(tailidx);
atom_cmpxchg(&q->tail, tailidx, PTR(nextidx, tag));
mem_fence(CLK_GLOBAL_MEM_FENCE);
} else {
tag = TAG(headidx);
if(atom_cmpxchg(&q->head, headidx, PTR(nextidx, tag)) == headidx)
break;
}
}
}
mem_fence(CLK_GLOBAL_MEM_FENCE);
return head;
}
/* Test enqueueing. */
__kernel void
clIndexedQueue_test_enqueue(void __global *queue, unsigned int __global *mem)
{
clIndexedQueue __global *q = (clIndexedQueue __global *) queue;
size_t pid = 0, j;
unsigned int i;
struct mem_item __global *item, *prev;
/* First find global unique ID */
for(i = 0, j = 1; i < get_work_dim(); i++) {
pid += j * get_global_id(i);
j *= get_global_size(i);
}
pid++;
item = (struct mem_item __global *) &mem[pid * 4];
idxd_enqueue(q, &item->q);
if(pid == 1) {
prev = (struct mem_item __global *) &mem[0];
prev->thisobj = (uintptr_t) &mem[0];
}
item->thisobj = (uintptr_t) item;
}
/* Test enqueueing, dequeueing. */
__kernel void
clIndexedQueue_test_dequeue(void __global *queue, unsigned int __global *mem)
{
clIndexedQueue __global *q = (clIndexedQueue __global *) queue;
size_t pid = 0, j;
unsigned int i;
struct mem_item __global *item, *prev;
/* First find global unique ID */
for(i = 0, j = 1; i < get_work_dim(); i++) {
pid += j * get_global_id(i);
j *= get_global_size(i);
}
pid++;
item = (struct mem_item __global *) &mem[pid * 4];
item->thisobj = (uintptr_t) item;
if(pid == 1) {
prev = (struct mem_item __global *) &mem[0];
prev->thisobj = (uintptr_t) &mem[0];
}
idxd_enqueue(q, (clIndexedQueue_item __global *) item);
/* Do the shuffle */
for(i = 0; i < 10; i++) {
item = (struct mem_item __global *) idxd_dequeue(q);
if(item != NULL) {
if(!idxd_enqueue(q, (clIndexedQueue_item __global *) item)) {
}
} else {
}
}
}