* work. SPE's dequeue from here.
*
* FIXME make it lock free ;) For now, use a spin lock.
+ *
+ * (Fills a single cache line)
*/
-
-typedef struct gc_jd_q_links
-{
- gc_eaddr_t head _AL16;
- gc_eaddr_t tail _AL16;
-} gc_jd_q_links_t;
-
-typedef struct gc_jd_q_mutex
-{
- uint32_t mutex; // libsync mutex (spin lock)
- uint32_t _pad[31]; // pad to cache line so we can use putlluc on SPE
-} _AL128 gc_jd_q_mutex_t;
-
-typedef struct gc_jd_q_flag
-{
- uint32_t flag; // host writes this after enqueuing
- uint32_t _pad[31]; // pad to cache line
-} _AL128 gc_jd_q_flag_t;
-
typedef struct gc_jd_queue
{
- gc_jd_q_links_t l;
- gc_jd_q_mutex_t m;
- gc_jd_q_flag_t f;
+ gc_eaddr_t head _AL16;
+ gc_eaddr_t tail _AL16;
+ uint32_t mutex _AL16; // libsync mutex (spin lock)
} _AL128 gc_jd_queue_t;
__GC_END_DECLS
gcellspuinclude_HEADERS = \
gc_delay.h \
- gc_jd_queue.h
+ gc_jd_queue.h \
+ gc_random.h
* \param[out] item is local store copy of item at head of queue.
* \returns false if the queue is empty, otherwise returns true
* and sets \p item_ea and DMA's job descriptor into \p item
+ *
+ * If return is false, we're holding a lock-line reservation that
+ * covers the queue.
*/
bool
gc_jd_queue_dequeue(gc_eaddr_t q, gc_eaddr_t *item_ea,
int jd_tag, gc_job_desc_t *item);
-
-/*!
- * \brief Get a line reservation on the queue
- *
- * \param[in] q is EA address of queue structure.
- */
-void
-gc_jd_queue_getllar(gc_eaddr_t q);
-
__GC_END_DECLS
--- /dev/null
+/* -*- c++ -*- */
+/*
+ * Copyright 2008 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * GNU Radio 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef INCLUDED_GC_RANDOM_H
+#define INCLUDED_GC_RANDOM_H
+
+/*!
+ * \brief Return a uniformly distributed value in the range [0, 1.0)
+ * (Linear congruential generator. YMMV. Caveat emptor.)
+ */
+
+float gc_uniform_deviate(void);
+void gc_set_seed(int seed);
+
+#endif /* INCLUDED_GC_RANDOM_H */
void
gc_jd_queue_init(gc_jd_queue_t *q)
{
- _mutex_init(ptr_to_ea(&q->m.mutex));
- q->l.head = 0;
- q->l.tail = 0;
- q->f.flag = 0;
+ _mutex_init(ptr_to_ea(&q->mutex));
+ q->head = 0;
+ q->tail = 0;
smp_wmb();
}
gc_jd_queue_enqueue(gc_jd_queue_t *q, gc_job_desc_t *item)
{
item->sys.next = 0;
- _mutex_lock(ptr_to_ea(&q->m.mutex));
+ _mutex_lock(ptr_to_ea(&q->mutex));
smp_rmb(); // import barrier
- if (q->l.tail == 0){ // currently empty
- q->l.tail = q->l.head = jdp_to_ea(item);
+ if (q->tail == 0){ // currently empty
+ q->tail = q->head = jdp_to_ea(item);
}
else { // not empty, append
- ea_to_jdp(q->l.tail)->sys.next = jdp_to_ea(item);
- q->l.tail = jdp_to_ea(item);
+ ea_to_jdp(q->tail)->sys.next = jdp_to_ea(item);
+ q->tail = jdp_to_ea(item);
}
smp_wmb(); // orders stores above before clearing of mutex
- _mutex_unlock(ptr_to_ea(&q->m.mutex));
-
- // let SPE's know we wrote something if they've got a lock-line reservation
- q->f.flag = 1;
+ _mutex_unlock(ptr_to_ea(&q->mutex));
}
gc_job_desc_t *
gc_jd_queue_dequeue(gc_jd_queue_t *q)
{
- _mutex_lock(ptr_to_ea(&q->m.mutex));
+ _mutex_lock(ptr_to_ea(&q->mutex));
smp_rmb(); // import barrier
- gc_eaddr_t item_ea = q->l.head;
+ gc_eaddr_t item_ea = q->head;
if (item_ea == 0){ // empty
- _mutex_unlock(ptr_to_ea(&q->m.mutex));
+ _mutex_unlock(ptr_to_ea(&q->mutex));
return 0;
}
- q->l.head = ea_to_jdp(item_ea)->sys.next;
- if (q->l.head == 0) // now emtpy
- q->l.tail = 0;
+ q->head = ea_to_jdp(item_ea)->sys.next;
+ if (q->head == 0) // now emtpy
+ q->tail = 0;
gc_job_desc_t *item = ea_to_jdp(item_ea);
item->sys.next = 0;
smp_wmb(); // orders stores above before clearing of mutex
- _mutex_unlock(ptr_to_ea(&q->m.mutex));
+ _mutex_unlock(ptr_to_ea(&q->mutex));
return item;
}
#include "gc_jd_queue.h"
#include "gc_delay.h"
#include "gc_declare_proc.h"
+#include "gc_random.h"
#include "spu_buffers.h"
#include <string.h>
#include <assert.h>
backoff = _backoff_start;
}
+#if 0
+
static void
backoff_delay(void)
{
backoff = ((backoff << 1) + 1) & _backoff_cap;
}
+#else
+
+#define RANDOM_WEIGHT 0.2
+
+static void
+backoff_delay(void)
+{
+ gc_cdelay(backoff);
+
+ backoff = ((backoff << 1) + 1);
+ if (backoff > _backoff_cap)
+ backoff = _backoff_cap;
+
+ float r = (RANDOM_WEIGHT * (2.0 * (gc_uniform_deviate() - 0.5)));
+ backoff = backoff * (1.0 + r);
+}
+
+#endif
+
// ------------------------------------------------------------------------
static inline unsigned int
gc_eaddr_t jd_ea;
int total_jobs = 0;
+#if (USE_LLR_LOST_EVENT)
// setup events
spu_writech(SPU_WrEventMask, MFC_LLR_LOST_EVENT);
- gc_jd_queue_getllar(spu_args.queue); // get a line reservation on the queue
+
+ // prime the pump
+ while (gc_jd_queue_dequeue(spu_args.queue, &jd_ea, ci_tags + ci_idx, &jd))
+ process_job(jd_ea, &jd);
+ // we're now holding a lock-line reservation
+#endif
while (1){
// by somebody doing something to the queue. Go look and see
// if there's anything for us.
//
- if (gc_jd_queue_dequeue(spu_args.queue, &jd_ea, ci_tags + ci_idx, &jd))
+ while (gc_jd_queue_dequeue(spu_args.queue, &jd_ea, ci_tags + ci_idx, &jd))
process_job(jd_ea, &jd);
-
- gc_jd_queue_getllar(spu_args.queue); // get a new reservation
}
//
// initialize pointer to procedure entry table
gc_proc_def = (gc_proc_def_t *) spu_args.proc_def_ls_addr;
+ gc_set_seed(spu_args.spu_idx);
+
// initialize logging
_gc_log_init(spu_args.log);
--- /dev/null
+/* -*- c++ -*- */
+/*
+ * Copyright 2008 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * GNU Radio 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include <gc_random.h>
+
+static int last_val = 0;
+
+#define M 714025 // values from Numerical Recipes in C, 1988
+#define A 4096
+#define C 150889
+
+void
+gc_set_seed(int seed)
+{
+ last_val = ((unsigned int) seed) % M;
+}
+
+float
+gc_uniform_deviate(void)
+{
+ last_val = (last_val * A + C) % M;
+ return (float) last_val / (float) M;
+}
/* -*- c++ -*- */
/*
- * Copyright 2007 Free Software Foundation, Inc.
+ * Copyright 2007,2008 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
#include "gc_jd_queue.h"
#include "mutex_lock.h"
#include "mutex_unlock.h"
+#include "gc_delay.h"
+#include "gc_random.h"
+
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
extern int gc_sys_tag;
-/*
- * ea must be 128-byte aligned, the mutex is in the first int32_t, and
- * it must be safe to write the remaining 124 bytes with anything at
- * all.
- */
-static __inline void _fast_mutex_unlock(mutex_ea_t ea)
+#define INITIAL_BACKOFF 32.0
+#define MAX_BACKOFF 16384.0
+#define RANDOM_WEIGHT 0.2
+
+static float
+next_backoff(float backoff)
{
- char _tmp[256];
- vector signed int *buf
- = (vector signed int *) ALIGN(_tmp, 128); // get cache-aligned buffer
+ // exponential with random
+ float t = backoff * 2.0;
+ if (t > MAX_BACKOFF)
+ t = MAX_BACKOFF;
- buf[0] = spu_splats(0); // the value that unlocks the mutex
+ float r = (RANDOM_WEIGHT * (2.0 * (gc_uniform_deviate() - 0.5)));
+ t = t * (1.0 + r);
- mfc_putlluc(buf, ea, 0, 0); // unconditional put, no reservation reqd
- spu_readch(MFC_RdAtomicStat);
+ return t;
}
-
-
bool
gc_jd_queue_dequeue(gc_eaddr_t q, gc_eaddr_t *item_ea,
int jd_tag, gc_job_desc_t *item)
{
- gc_jd_q_links_t local_q;
+ int status;
+ char _tmp[256];
+ gc_jd_queue_t *local_q =
+ (gc_jd_queue_t *) ALIGN(_tmp, 128); // get cache-aligned buffer
+
+ float backoff = next_backoff(INITIAL_BACKOFF);
- // Before aquiring the lock, see if it's possible that there's
- // something in the queue. Checking in this way makes it easier
- // for the PPE to insert things, since we're not contending for
- // the lock unless there is something in the queue.
+ do {
+ // Copy the queue structure in and get a lock line reservation.
+ // (The structure is 128-byte aligned and completely fills a cache-line)
- // copy in the queue structure
- mfc_get(&local_q, q, sizeof(local_q), gc_sys_tag, 0, 0);
- mfc_write_tag_mask(1 << gc_sys_tag); // the tag we're interested in
- mfc_read_tag_status_all(); // wait for DMA to complete
+ mfc_getllar(local_q, q, 0, 0);
+ spu_readch(MFC_RdAtomicStat);
- if (local_q.head == 0){ // empty
- return false;
- }
+ if (local_q->mutex != 0) // somebody else has it locked
+ return false;
- // When we peeked, head was non-zero. Now grab the
- // lock and do it for real.
+ if (local_q->head == 0) // the queue is empty
+ return false;
- _mutex_lock(q + offsetof(gc_jd_queue_t, m.mutex));
+ // Try to acquire the lock
- // copy in the queue structure
- mfc_get(&local_q, q, sizeof(local_q), gc_sys_tag, 0, 0);
- mfc_write_tag_mask(1 << gc_sys_tag); // the tag we're interested in
- mfc_read_tag_status_all(); // wait for DMA to complete
+ local_q->mutex = 1;
+ mfc_putllc(local_q, q, 0, 0);
+ status = spu_readch(MFC_RdAtomicStat);
+
+ if (status != 0){
+ gc_cdelay((int) backoff);
+ backoff = next_backoff(backoff);
+ }
- if (local_q.head == 0){ // empty
- _fast_mutex_unlock(q + offsetof(gc_jd_queue_t, m.mutex));
- return false;
- }
+ } while (status != 0);
+ // we're now holding the lock
+
// copy in job descriptor at head of queue
- *item_ea = local_q.head;
+ *item_ea = local_q->head;
// We must use the fence with the jd_tag to ensure that any
// previously initiated put of a job desc is locally ordered before
// the get of the new one.
- mfc_getf(item, local_q.head, sizeof(gc_job_desc_t), jd_tag, 0, 0);
+ mfc_getf(item, local_q->head, sizeof(gc_job_desc_t), jd_tag, 0, 0);
mfc_write_tag_mask(1 << jd_tag); // the tag we're interested in
mfc_read_tag_status_all(); // wait for DMA to complete
- local_q.head = item->sys.next;
+ local_q->head = item->sys.next;
item->sys.next = 0;
- if (local_q.head == 0) // now empty?
- local_q.tail = 0;
-
+ if (local_q->head == 0) // now empty?
+ local_q->tail = 0;
- // copy the queue structure back out
- mfc_put(&local_q, q, sizeof(local_q), gc_sys_tag, 0, 0);
- mfc_write_tag_mask(1 << gc_sys_tag); // the tag we're interested in
- mfc_read_tag_status_all(); // wait for DMA to complete
+ // Copy the queue struct back out and unlock the mutex in one fell swoop.
+ // We use the unconditional put since it's faster and we own the lock.
- // Q: FIXME do we need to order stores in EA or can we just clear the
- // local copy of the mutex above and blast it out, removing the need
- // for this explicit unlock?
- //
- // A: Manual says it's better to use an atomic op rather than
- // a normal DMA, and that a putlluc is better than a putllc if
- // you can use it.
+ local_q->mutex = 0;
+ mfc_putlluc(local_q, q, 0, 0);
+ spu_readch(MFC_RdAtomicStat);
- _fast_mutex_unlock(q + offsetof(gc_jd_queue_t, m.mutex));
return true;
}
-
-
-void
-gc_jd_queue_getllar(gc_eaddr_t q)
-{
- // get reservation that includes the flag in the queue
- gc_eaddr_t ea = q + offsetof(gc_jd_queue_t, f.flag);
-
- char _tmp[256];
- char *buf = (char *) ALIGN(_tmp, 128); // get cache-aligned buffer
-
- mfc_getllar(buf, ALIGN128_EA(ea), 0, 0);
- spu_readch(MFC_RdAtomicStat);
-}
$(runtime_srcdir)/gc_spu_jd_queue.c \
$(runtime_srcdir)/spu_buffers.c \
$(runtime_srcdir)/gc_logging.c \
- $(runtime_srcdir)/gc_main.c
+ $(runtime_srcdir)/gc_main.c \
+ $(runtime_srcdir)/gc_random.c
+
runtime_spu_headers =
projects / debian / gnuradio / commitdiff