From 6fdf3b21433e901dcba0ac186f00d604ce944f56 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" Date: Sat, 1 Dec 2012 06:46:32 -0800 Subject: [PATCH] Drivers: hv: Implement routines for read side signaling optimization Implement functions that will support read-side signaling optimization. By having the reader indicate the start of the "read" operation and the "end" of the read operation we can more efficiently handle the signaling protocol: while the read is in progress, there is no need for the "writer" to signal the "reader" as new items are put on the read queue. Signed-off-by: K. Y. Srinivasan Reviewed-by: Haiyang Zhang Signed-off-by: Greg Kroah-Hartman --- drivers/hv/hyperv_vmbus.h | 4 ++++ drivers/hv/ring_buffer.c | 24 ++++++++++++++++++++++++ 2 files changed, 28 insertions(+) diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h index d8d1fadb398a..3184f6ff4e74 100644 --- a/drivers/hv/hyperv_vmbus.h +++ b/drivers/hv/hyperv_vmbus.h @@ -570,6 +570,10 @@ u32 hv_get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *ring_info); void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, struct hv_ring_buffer_debug_info *debug_info); +void hv_begin_read(struct hv_ring_buffer_info *rbi); + +u32 hv_end_read(struct hv_ring_buffer_info *rbi); + /* * Maximum channels is determined by the size of the interrupt page * which is PAGE_SIZE. 1/2 of PAGE_SIZE is for send endpoint interrupt diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 7233c88f01b8..001079287709 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -29,6 +29,30 @@ #include "hyperv_vmbus.h" +void hv_begin_read(struct hv_ring_buffer_info *rbi) +{ + rbi->ring_buffer->interrupt_mask = 1; + smp_mb(); +} + +u32 hv_end_read(struct hv_ring_buffer_info *rbi) +{ + u32 read; + u32 write; + + rbi->ring_buffer->interrupt_mask = 0; + smp_mb(); + + /* + * Now check to see if the ring buffer is still empty. + * If it is not, we raced and we need to process new + * incoming messages. + */ + hv_get_ringbuffer_availbytes(rbi, &read, &write); + + return read; +} + /* * hv_get_next_write_location() -- 2.39.5