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Commit ce10c1b9 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

virtio: add inorder option 



skips ring accesses but drops out of order support

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 2dcd0af5

tools/virtio/ringtest/Makefile

+4 −1
Original line number Diff line number Diff line 
all:



all: ring virtio_ring_0_9 virtio_ring_poll

all: ring virtio_ring_0_9 virtio_ring_poll virtio_ring_inorder



CFLAGS += -Wall

CFLAGS += -pthread -O2 -ggdb
@@ -10,13 +10,16 @@ main.o: main.c main.h 
ring.o: ring.c main.h

virtio_ring_0_9.o: virtio_ring_0_9.c main.h

virtio_ring_poll.o: virtio_ring_poll.c virtio_ring_0_9.c main.h

virtio_ring_inorder.o: virtio_ring_inorder.c virtio_ring_0_9.c main.h

ring: ring.o main.o

virtio_ring_0_9: virtio_ring_0_9.o main.o

virtio_ring_poll: virtio_ring_poll.o main.o

virtio_ring_inorder: virtio_ring_inorder.o main.o

clean:

	-rm main.o

	-rm ring.o ring

	-rm virtio_ring_0_9.o virtio_ring_0_9

	-rm virtio_ring_poll.o virtio_ring_poll

	-rm virtio_ring_inorder.o virtio_ring_inorder



.PHONY: all clean

tools/virtio/ringtest/virtio_ring_0_9.c

+48 −1
Original line number Diff line number Diff line
@@ -26,6 +26,14 @@ struct vring ring; 
 * high bits of ring id ^ 0x8000).

 */

/* #ifdef RING_POLL */

/* enabling the below activates experimental in-order code

 * (which skips ring updates and reads and writes len in descriptor).

 */

/* #ifdef INORDER */



#if defined(RING_POLL) && defined(INORDER)

#error "RING_POLL and INORDER are mutually exclusive"

#endif



/* how much padding is needed to avoid false cache sharing */

#define HOST_GUEST_PADDING 0x80
@@ -35,7 +43,11 @@ struct guest { 
	unsigned short last_used_idx;

	unsigned short num_free;

	unsigned short kicked_avail_idx;

#ifndef INORDER

	unsigned short free_head;

#else

	unsigned short reserved_free_head;

#endif

	unsigned char reserved[HOST_GUEST_PADDING - 10];

} guest;
@@ -66,8 +78,10 @@ void alloc_ring(void) 
	guest.avail_idx = 0;

	guest.kicked_avail_idx = -1;

	guest.last_used_idx = 0;

#ifndef INORDER

	/* Put everything in free lists. */

	guest.free_head = 0;

#endif

	for (i = 0; i < ring_size - 1; i++)

		ring.desc[i].next = i + 1;

	host.used_idx = 0;
@@ -84,13 +98,20 @@ void alloc_ring(void) 
/* guest side */

int add_inbuf(unsigned len, void *buf, void *datap)

{

	unsigned head, avail;

	unsigned head;

#ifndef INORDER

	unsigned avail;

#endif

	struct vring_desc *desc;



	if (!guest.num_free)

		return -1;



#ifdef INORDER

	head = (ring_size - 1) & (guest.avail_idx++);

#else

	head = guest.free_head;

#endif

	guest.num_free--;



	desc = ring.desc;
@@ -102,7 +123,9 @@ int add_inbuf(unsigned len, void *buf, void *datap) 
	 * descriptors.

	 */

	desc[head].flags &= ~VRING_DESC_F_NEXT;

#ifndef INORDER

	guest.free_head = desc[head].next;

#endif



	data[head].data = datap;
@@ -113,8 +136,12 @@ int add_inbuf(unsigned len, void *buf, void *datap) 
	ring.avail->ring[avail & (ring_size - 1)] =

		(head | (avail & ~(ring_size - 1))) ^ 0x8000;

#else

#ifndef INORDER

	/* Barrier A (for pairing) */

	smp_release();

	avail = (ring_size - 1) & (guest.avail_idx++);

	ring.avail->ring[avail] = head;

#endif

	/* Barrier A (for pairing) */

	smp_release();

#endif
@@ -141,15 +168,27 @@ void *get_buf(unsigned *lenp, void **bufp) 
		return NULL;

	/* Barrier B (for pairing) */

	smp_acquire();

#ifdef INORDER

	head = (ring_size - 1) & guest.last_used_idx;

	index = head;

#else

	head = (ring_size - 1) & guest.last_used_idx;

	index = ring.used->ring[head].id;

#endif



#endif

#ifdef INORDER

	*lenp = ring.desc[index].len;

#else

	*lenp = ring.used->ring[head].len;

#endif

	datap = data[index].data;

	*bufp = (void*)(unsigned long)ring.desc[index].addr;

	data[index].data = NULL;

#ifndef INORDER

	ring.desc[index].next = guest.free_head;

	guest.free_head = index;

#endif

	guest.num_free++;

	guest.last_used_idx++;

	return datap;
@@ -283,16 +322,24 @@ bool use_buf(unsigned *lenp, void **bufp) 
	smp_acquire();



	used_idx &= ring_size - 1;

#ifdef INORDER

	head = used_idx;

#else

	head = ring.avail->ring[used_idx];

#endif

	desc = &ring.desc[head];

#endif



	*lenp = desc->len;

	*bufp = (void *)(unsigned long)desc->addr;



#ifdef INORDER

	desc->len = desc->len - 1;

#else

	/* now update used ring */

	ring.used->ring[used_idx].id = head;

	ring.used->ring[used_idx].len = desc->len - 1;

#endif

	/* Barrier B (for pairing) */

	smp_release();

	host.used_idx++;

tools/virtio/ringtest/virtio_ring_inorder.c

0 → 100644
+2 −0
Original line number Diff line number Diff line 
#define INORDER 1

#include "virtio_ring_0_9.c"