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authorHaiyang Zhang <haiyangz@microsoft.com>2012-03-27 13:20:45 +0000
committerDavid S. Miller <davem@davemloft.net>2012-04-03 17:47:15 -0400
commit33be96e47cc27f2f1a753a0707b02a73df8c8d46 (patch)
tree2b0361f4d39a14e2ddd0d23e66656e6174b3cb71 /include
parentede7193d4fdca98178240500d8684dbc139ca26f (diff)
net/hyperv: Add flow control based on hi/low watermark
In the existing code, we only stop queue when the ringbuffer is full, so the current packet has to be dropped or retried from upper layer. This patch stops the tx queue when available ringbuffer is below the low watermark. So the ringbuffer still has small amount of space available for the current packet. This will reduce the overhead of retries on sending. Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> Reviewed-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/hyperv.h27
1 files changed, 27 insertions, 0 deletions
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 5852545e6bb..6af8738ae7e 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -274,6 +274,33 @@ struct hv_ring_buffer_debug_info {
u32 bytes_avail_towrite;
};
+
+/*
+ *
+ * hv_get_ringbuffer_availbytes()
+ *
+ * Get number of bytes available to read and to write to
+ * for the specified ring buffer
+ */
+static inline void
+hv_get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
+ u32 *read, u32 *write)
+{
+ u32 read_loc, write_loc, dsize;
+
+ smp_read_barrier_depends();
+
+ /* Capture the read/write indices before they changed */
+ read_loc = rbi->ring_buffer->read_index;
+ write_loc = rbi->ring_buffer->write_index;
+ dsize = rbi->ring_datasize;
+
+ *write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
+ read_loc - write_loc;
+ *read = dsize - *write;
+}
+
+
/*
* We use the same version numbering for all Hyper-V modules.
*