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[uml-devel] [PATCH 3/3] Scatter Gather support for vector IO in UML
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From: <ant...@ko...> - 2017-07-17 07:12:38
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From: Anton Ivanov <ant...@ca...>
Adds scatter gather support to the vector network drivers.
Provides additional 55% performance improvement for most
network applications running in the UML instance.
Signed-off-by: Anton Ivanov <ant...@ca...>
---
arch/um/drivers/vector_kern.c | 63 +++++++++++++++++++++++++++++++++----------
arch/um/drivers/vector_kern.h | 4 ++-
2 files changed, 52 insertions(+), 15 deletions(-)
diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index ee61f1338b0f..4142a0a782bd 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -75,6 +75,7 @@ static void vector_eth_configure(int n, struct arglist *def);
#define SAFETY_MARGIN 32
#define DEFAULT_VECTOR_SIZE 64
#define TX_SMALL_PACKET 128
+#define MAX_IOV_SIZE 8
static const struct {
const char string[ETH_GSTRING_LEN];
@@ -90,7 +91,9 @@ static const struct {
{ "tx_flow_control_xon" },
{ "tx_flow_control_xoff" },
{ "rx_csum_offload_good" },
- { "rx_csum_offload_errors"}
+ { "rx_csum_offload_errors"},
+ { "sg_ok"},
+ { "sg_linearized"},
};
#define VECTOR_NUM_STATS ARRAY_SIZE(ethtool_stats_keys)
@@ -119,6 +122,8 @@ static void vector_reset_stats(struct vector_private *vp)
vp->estats.tx_kicks = 0;
vp->estats.tx_flow_control_xon = 0;
vp->estats.tx_flow_control_xoff = 0;
+ vp->estats.sg_ok = 0;
+ vp->estats.sg_linearized = 0;
}
static int get_mtu(struct arglist *def)
@@ -247,14 +252,18 @@ static int vector_enqueue(struct vector_queue *qi, struct sk_buff *skb)
{
struct vector_private *vp = netdev_priv(qi->dev);
int queue_depth;
+ int nr_frags, frag, packet_len;
struct mmsghdr *mmsg_vector = qi->mmsg_vector;
struct iovec *iov;
+ skb_frag_t *skb_frag;
spin_lock(&qi->tail_lock);
spin_lock(&qi->head_lock);
queue_depth = qi->queue_depth;
spin_unlock(&qi->head_lock);
+ if (skb)
+ packet_len = skb->len;
if (queue_depth < qi->max_depth) {
@@ -264,19 +273,41 @@ static int vector_enqueue(struct vector_queue *qi, struct sk_buff *skb)
mmsg_vector->msg_hdr.msg_name = vp->fds->remote_addr;
mmsg_vector->msg_hdr.msg_namelen = vp->fds->remote_addr_size;
+ nr_frags = skb_shinfo(skb)->nr_frags;
if (vp->header_size > 0) {
vp->form_header(iov->iov_base, skb, vp);
iov++;
- }
+ mmsg_vector->msg_hdr.msg_iovlen = 2 + nr_frags;
+ } else
+ mmsg_vector->msg_hdr.msg_iovlen = 1 + nr_frags;
+ if (nr_frags > qi->max_iov_frags) {
+ if (skb_linearize(skb) != 0)
+ goto drop;
+ else
+ vp->estats.sg_linearized++;
+ } else
+ vp->estats.sg_ok++;
iov->iov_base = skb->data;
- iov->iov_len = skb->len;
- queue_depth = vector_advancetail(qi, 1);
- } else {
- qi->dev->stats.tx_dropped++;
- if (skb != NULL) {
- dev_consume_skb_any(skb);
- netdev_completed_queue(qi->dev, 1, skb->len);
+ if (nr_frags > 0)
+ iov->iov_len = skb->len - skb->data_len;
+ else
+ iov->iov_len = skb->len;
+ for (frag = 0; frag < nr_frags; frag++) {
+ iov++;
+ skb_frag = &skb_shinfo(skb)->frags[frag];
+ iov->iov_base = skb_frag_address_safe(skb_frag);
+ iov->iov_len = skb_frag_size(skb_frag);
}
+ queue_depth = vector_advancetail(qi, 1);
+ } else
+ goto drop;
+ spin_unlock(&qi->tail_lock);
+ return queue_depth;
+drop:
+ qi->dev->stats.tx_dropped++;
+ if (skb != NULL) {
+ dev_consume_skb_any(skb);
+ netdev_completed_queue(qi->dev, 1, packet_len);
}
spin_unlock(&qi->tail_lock);
return queue_depth;
@@ -424,7 +455,8 @@ static void destroy_queue(struct vector_queue *qi)
static struct vector_queue *create_queue(
struct vector_private *vp,
int max_size,
- int header_size)
+ int header_size,
+ int num_extra_frags)
{
struct vector_queue *result;
int i;
@@ -455,9 +487,9 @@ static struct vector_queue *create_queue(
mmsg_vector = result->mmsg_vector;
for (i = 0; i < max_size; i++) {
if (vp->header_size > 0)
- iov = kmalloc(sizeof(struct iovec) * 2, GFP_KERNEL);
+ iov = kmalloc(sizeof(struct iovec) * (2 + num_extra_frags), GFP_KERNEL);
else
- iov = kmalloc(sizeof(struct iovec), GFP_KERNEL);
+ iov = kmalloc(sizeof(struct iovec) * (1 + num_extra_frags), GFP_KERNEL);
if (iov == NULL)
goto out_fail;
mmsg_vector->msg_hdr.msg_iov = iov;
@@ -1049,7 +1081,7 @@ static int vector_net_open(struct net_device *dev)
goto out_close;
if ((vp->options & VECTOR_RX) > 0) {
vp->rx_queue = create_queue(
- vp, get_depth(vp->parsed), vp->rx_header_size);
+ vp, get_depth(vp->parsed), vp->rx_header_size, 0);
vp->rx_queue->queue_depth = get_depth(vp->parsed);
} else {
vp->header_rxbuffer = kmalloc(vp->rx_header_size, GFP_KERNEL);
@@ -1061,7 +1093,7 @@ static int vector_net_open(struct net_device *dev)
goto out_close;
if ((vp->options & VECTOR_TX) > 0)
vp->tx_queue = create_queue(
- vp, get_depth(vp->parsed), vp->header_size);
+ vp, get_depth(vp->parsed), vp->header_size, MAX_IOV_SIZE);
/* READ IRQ */
err = um_request_irq(
@@ -1335,6 +1367,9 @@ static void vector_eth_configure(
.coalesce = 2
});
+ /* if we can do vector TX, we can do scatter/gather too */
+ if ((vp->options & VECTOR_TX) > 0)
+ dev->features = NETIF_F_SG;
tasklet_init(&vp->tx_poll, vector_tx_poll, (unsigned long)vp);
INIT_WORK(&vp->reset_tx, vector_reset_tx);
diff --git a/arch/um/drivers/vector_kern.h b/arch/um/drivers/vector_kern.h
index 7505ed8a4e37..c10d746ae6e4 100644
--- a/arch/um/drivers/vector_kern.h
+++ b/arch/um/drivers/vector_kern.h
@@ -39,7 +39,7 @@ struct vector_queue {
struct net_device *dev;
spinlock_t head_lock;
spinlock_t tail_lock;
- int queue_depth, head, tail, max_depth;
+ int queue_depth, head, tail, max_depth, max_iov_frags;
short options;
};
@@ -56,6 +56,8 @@ struct vector_estats {
uint64_t tx_flow_control_xoff;
uint64_t rx_csum_offload_good;
uint64_t rx_csum_offload_errors;
+ uint64_t sg_ok;
+ uint64_t sg_linearized;
};
struct vector_private {
--
2.11.0
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