Commit f4cb9817 authored by Ben Walker's avatar Ben Walker Committed by Jim Harris
Browse files

util/pipe: add pipe empty check 



When read catches write, jump back to the beginning. This makes it
more likely to re-use a fewer number of cache lines.

Change-Id: I9910911dde7dbeb883e3c405e4a528665b1a3bc7
Signed-off-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16991


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarAleksey Marchuk <alexeymar@nvidia.com>
Community-CI: Mellanox Build Bot
Reviewed-by: default avatarJacek Kalwas <jacek.kalwas@intel.com>
Reviewed-by: default avatarJim Harris <jim.harris@samsung.com>
parent f506f14e

lib/util/pipe.c

+8 −0
Original line number Diff line number Diff line
@@ -229,6 +229,14 @@ spdk_pipe_reader_advance(struct spdk_pipe *pipe, uint32_t requested_sz) 


	/* We know we advanced at least one byte, so the pipe isn't full. */

	pipe->full = false;



	if (read == write) {

		/* The pipe is empty. To re-use the same memory more frequently, jump

		 * both pointers back to the beginning of the pipe. */

		read = 0;

		pipe->write = 0;

	}



	pipe->read = read;



	return 0;

test/unit/lib/util/pipe.c/pipe_ut.c

+24 −21
Original line number Diff line number Diff line
@@ -410,11 +410,12 @@ test_read_advance(void) 
	pipe->read = 0;

	pipe->write = 9;



	/* Advance to the end of the pipe */

	/* Advance to the end of the pipe, which resets

	 * it back to the beginning */

	rc = spdk_pipe_reader_advance(pipe, 9);

	CU_ASSERT(rc == 0);

	CU_ASSERT(pipe->read == 9);

	CU_ASSERT(pipe->write == 9);

	CU_ASSERT(pipe->read == 0);

	CU_ASSERT(pipe->write == 0);



	pipe->read = 0;

	pipe->write = 9;
@@ -429,11 +430,12 @@ test_read_advance(void) 
	pipe->read = 0;

	pipe->write = 5;



	/* Advance to the end of the pipe */

	/* Advance to the end of the pipe, which resets

	 * it back to the beginning */

	rc = spdk_pipe_reader_advance(pipe, 5);

	CU_ASSERT(rc == 0);

	CU_ASSERT(pipe->write == 5);

	CU_ASSERT(pipe->read == 5);

	CU_ASSERT(pipe->write == 0);

	CU_ASSERT(pipe->read == 0);



	pipe->read = 0;

	pipe->write = 5;
@@ -448,11 +450,12 @@ test_read_advance(void) 
	pipe->read = 7;

	pipe->write = 3;



	/* Advance to the end of the pipe */

	/* Advance to the end of the pipe, which resets

	 * it back to the beginning */

	rc = spdk_pipe_reader_advance(pipe, 6);

	CU_ASSERT(rc == 0);

	CU_ASSERT(pipe->read == 3);

	CU_ASSERT(pipe->write == 3);

	CU_ASSERT(pipe->read == 0);

	CU_ASSERT(pipe->write == 0);



	pipe->read = 7;

	pipe->write = 3;
@@ -485,7 +488,7 @@ test_data(void) 
	/* Place 1 byte in the pipe */

	rc = spdk_pipe_writer_get_buffer(pipe, 1, iovs);

	CU_ASSERT(rc == 1);

	CU_ASSERT(iovs[0].iov_base != NULL);

	CU_ASSERT(iovs[0].iov_base == mem);

	CU_ASSERT(iovs[0].iov_len == 1);



	memset(iovs[0].iov_base, 'A', 1);
@@ -516,8 +519,8 @@ test_data(void) 


	spdk_pipe_reader_advance(pipe, 1);



	/* Put 9 more bytes in the pipe, so every byte has

	 * been written */

	/* Put 9 more bytes in the pipe. The previous advance

	 * should have reset the pipe to the beginning. */

	rc = spdk_pipe_writer_get_buffer(pipe, 9, iovs);

	CU_ASSERT(rc == 9);

	CU_ASSERT(iovs[0].iov_len == 9);
@@ -528,7 +531,7 @@ test_data(void) 
	rc = spdk_pipe_writer_advance(pipe, 9);

	CU_ASSERT(rc == 0);



	CU_ASSERT(mem[0] == 'A');

	CU_ASSERT(mem[0] == 'B');

	CU_ASSERT(mem[1] == 'B');

	CU_ASSERT(mem[2] == 'B');

	CU_ASSERT(mem[3] == 'B');
@@ -537,7 +540,7 @@ test_data(void) 
	CU_ASSERT(mem[6] == 'B');

	CU_ASSERT(mem[7] == 'B');

	CU_ASSERT(mem[8] == 'B');

	CU_ASSERT(mem[9] == 'B');

	CU_ASSERT(mem[9] == 0);



	memset(iovs, 0, sizeof(iovs));
@@ -556,7 +559,7 @@ test_data(void) 


	memset(iovs, 0, sizeof(iovs));



	/* Put 1 more byte in the pipe, overwriting the original 'A' */

	/* Put 1 more byte in the pipe */

	rc = spdk_pipe_writer_get_buffer(pipe, 1, iovs);

	CU_ASSERT(rc == 1);

	CU_ASSERT(iovs[0].iov_len == 1);
@@ -567,7 +570,7 @@ test_data(void) 
	rc = spdk_pipe_writer_advance(pipe, 1);

	CU_ASSERT(rc == 0);



	CU_ASSERT(mem[0] == 'C');

	CU_ASSERT(mem[0] == 'B');

	CU_ASSERT(mem[1] == 'B');

	CU_ASSERT(mem[2] == 'B');

	CU_ASSERT(mem[3] == 'B');
@@ -576,7 +579,7 @@ test_data(void) 
	CU_ASSERT(mem[6] == 'B');

	CU_ASSERT(mem[7] == 'B');

	CU_ASSERT(mem[8] == 'B');

	CU_ASSERT(mem[9] == 'B');

	CU_ASSERT(mem[9] == 'C');



	memset(iovs, 0, sizeof(iovs));
@@ -584,14 +587,14 @@ test_data(void) 
	CU_ASSERT(spdk_pipe_reader_bytes_available(pipe) == 3);

	rc = spdk_pipe_reader_get_buffer(pipe, 3, iovs);

	CU_ASSERT(rc == 3);

	CU_ASSERT(iovs[0].iov_len == 2);

	CU_ASSERT(iovs[1].iov_len == 1);

	CU_ASSERT(iovs[0].iov_len == 3);

	CU_ASSERT(iovs[1].iov_len == 0);



	data = iovs[0].iov_base;

	CU_ASSERT(data[0] == 'B');

	CU_ASSERT(data[1] == 'B');

	data = iovs[1].iov_base;

	CU_ASSERT(data[0] == 'C');

	CU_ASSERT(data[2] == 'C');

	CU_ASSERT(iovs[1].iov_base == NULL);



	spdk_pipe_reader_advance(pipe, 3);