diff --git a/buffers/zio-buf-vmalloc.c b/buffers/zio-buf-vmalloc.c
index 636eac03dcda380dc1aae4c814ccdca8e042eed7..1985c4dd4822fe9daa2915a23d16cafaa9af1743 100644
--- a/buffers/zio-buf-vmalloc.c
+++ b/buffers/zio-buf-vmalloc.c
@@ -34,9 +34,12 @@ struct zbk_instance {
struct zio_ffa *ffa;
void *data;
unsigned long size;
+ unsigned long flags;
};
#define to_zbki(bi) container_of(bi, struct zbk_instance, bi)
+#define ZBK_FLAG_MERGE_DATA 1
+
static struct kmem_cache *zbk_slab;
@@ -50,18 +53,43 @@ struct zbk_item {
};
#define to_item(block) container_of(block, struct zbk_item, block);
+enum {
+ ZBK_ATTR_MERGE_DATA = ZIO_MAX_STD_ATTR,
+};
+
static ZIO_ATTR_DEFINE_STD(ZIO_BUF, zbk_std_zattr) = {
ZIO_ATTR(zbuf, ZIO_ATTR_ZBUF_MAXKB, S_IRUGO | S_IWUGO, 0x0, 128),
};
+static struct zio_attribute zbk_ext_attr[] = {
+ ZIO_ATTR_EXT("merge-data", S_IRUGO | S_IWUGO,
+ ZBK_ATTR_MERGE_DATA, 0),
+};
+
static int zbk_conf_set(struct device *dev, struct zio_attribute *zattr,
uint32_t usr_val)
{
- if (0) {
- zattr->value = usr_val;
- } else {
- /* Temporarily, until I keep track of active maps */
- return -EBUSY;
+ struct zio_bi *bi = to_zio_bi(dev);
+ struct zbk_instance *zbki = to_zbki(bi);
+
+ switch(zattr->id) {
+ case ZIO_ATTR_ZBUF_MAXKB:
+ if (0) {
+ zattr->value = usr_val;
+ } else {
+ /* Temporarily, until I keep track of active maps */
+ return -EBUSY;
+ }
+ break;
+ case ZBK_ATTR_MERGE_DATA:
+ printk("write merge data: %i\n", usr_val);
+ if (usr_val)
+ zbki->flags |= ZBK_FLAG_MERGE_DATA;
+ else
+ zbki->flags &= ~ZBK_FLAG_MERGE_DATA;
+ break;
+ default:
+ return -EINVAL;
}
return 0;
}
@@ -121,6 +149,30 @@ static void zbk_free_block(struct zio_bi *bi, struct zio_block *block)
kmem_cache_free(zbk_slab, item);
}
+/* An helper for store_block() if we are trying to merge data runs */
+static void zbk_try_merge(struct zbk_instance *zbki, struct zbk_item *item)
+{
+ struct zbk_item *prev;
+ struct zio_control *ctrl, *prevc;
+
+ /* Called while locked and already part of the list */
+ prev = list_entry(item->list.prev, struct zbk_item, list);
+ if (prev->begin + prev->len != item->begin)
+ return; /* no, thanks */
+
+ /* merge: remove from list, fix prev block, remove new control */
+ list_del(&item->list);
+ ctrl = zio_get_ctrl(&item->block);
+ prevc = zio_get_ctrl(&prev->block);
+
+ prev->len += item->len; /* for the allocator */
+ prev->block.datalen += item->block.datalen; /* for copying */
+ prevc->nsamples += ctrl->nsamples; /* meta information */
+
+ zio_free_control(ctrl);
+ kmem_cache_free(zbk_slab, item);
+}
+
/* When write() stores the first block, we try pushing it */
static inline int __try_push(struct zio_bi *bi, struct zio_channel *chan,
struct zio_block *block)
@@ -171,6 +223,8 @@ static int zbk_store_block(struct zio_bi *bi, struct zio_block *block)
}
if (pushed)
list_del(&item->list);
+ if (!first && zbki->flags & ZBK_FLAG_MERGE_DATA)
+ zbk_try_merge(zbki, item);
spin_unlock(&bi->lock);
/* if first input, awake user space */
@@ -319,6 +373,8 @@ static struct zio_buffer_type zbk_buffer = {
.owner = THIS_MODULE,
.zattr_set = {
.std_zattr = zbk_std_zattr,
+ .ext_zattr = zbk_ext_attr,
+ .n_ext_attr = ARRAY_SIZE(zbk_ext_attr),
},
.s_op = &zbk_sysfs_ops,
.b_op = &zbk_buffer_ops,
diff --git a/doc/zio-manual.in b/doc/zio-manual.in
index 2d84e70c5a5cdd641938511d6912b9dca7c8a3f8..586f1e60509f30620c7aed9d96788e5195ade8f2 100644
--- a/doc/zio-manual.in
+++ b/doc/zio-manual.in
@@ -1404,31 +1404,27 @@ in @ref{fig:mmap}.
@end float
@sp 1
-Another option, offered by a buffer called @i{circ} is sticking
-several data blocks together to immediately release some control
-structures. The user may choose this buffer if the application knows
+An attribute of the @i{vmalloc} buffer, can turn it into a
+real circular buffer: individual buffer instances can merge
+(sticks together)
+several data blocks, in order to immediately release some control
+structures. The user may activate the attribute if the application knows
it won't need meta-data for every block: if you know you acquire at
1kHz, for example, time-stamping the first sample may be enough,
-whereas further streaming is self-timed. This buffer doesn't break
-the ZIO data model because whenever a new data block arrives, it is
+whereas further streaming is self-timed. The attribute doesn't break
+the ZIO data model because whenever a new data block arrives it is
stuck to the previous data by releasing the new control and increasing
the block size of the previous block; when a block enters an empty
-buffer, its own control is preserved (but its @t{nsmaples} field may
-be increased later, before the user reads the block). The @i{control +
+buffer, its own control is preserved (but its own @t{nsmaples} field may
+be increased later if another data blob is merged to it). The @i{control +
data} abstraction will thus continue working towards user space. This
-buffer is shown in @ref{fig:circ}
+situation is shown in @ref{fig:circ}.
@float Figure,fig:circ
@image{img/zio-buffer-data, 15cm, , the circular buffer and char devices, gif}
@end float
@sp 1
-
-@c FIXME: merge circular buffer
-This buffer is not yet merged to the official distribution at this point,
-because we need to upgrade it and perform more testing to ensure there are
-no bugs left.
-
@c ==========================================================================
@node User Space Utilities
@section User Space Utilities