msm: bam_dmux: Introduce watermarking in client transmit queue
BAM_DMUX does not put any restriction on the number of packets in
flight over the underlying BAM transport. This causes the bandwidth
to be not shared fairly among the clients. So introduce the concept
of watermarking in each client's transmit queue so that the clients
share the transport fairly and efficiently under high throughput
uplink scenarios
Change-Id: Ibf7e12b4cf13e826e7f83a41821f435cb7aa2cb0
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
diff --git a/arch/arm/mach-msm/bam_dmux.c b/arch/arm/mach-msm/bam_dmux.c
index ede298d..e3ca6d1 100644
--- a/arch/arm/mach-msm/bam_dmux.c
+++ b/arch/arm/mach-msm/bam_dmux.c
@@ -45,6 +45,8 @@
#define POLLING_MAX_SLEEP 1050 /* 1.05 ms */
#define POLLING_INACTIVITY 40 /* cycles before switch to intr mode */
+#define LOW_WATERMARK 2
+#define HIGH_WATERMARK 4
static int msm_bam_dmux_debug_enable;
module_param_named(debug_enable, msm_bam_dmux_debug_enable,
@@ -104,6 +106,8 @@
spinlock_t lock;
struct platform_device *pdev;
char name[BAM_DMUX_CH_NAME_MAX_LEN];
+ int num_tx_pkts;
+ int use_wm;
};
struct tx_pkt_info {
@@ -318,6 +322,7 @@
case BAM_MUX_HDR_CMD_OPEN:
spin_lock_irqsave(&bam_ch[rx_hdr->ch_id].lock, flags);
bam_ch[rx_hdr->ch_id].status |= BAM_CH_REMOTE_OPEN;
+ bam_ch[rx_hdr->ch_id].num_tx_pkts = 0;
spin_unlock_irqrestore(&bam_ch[rx_hdr->ch_id].lock, flags);
queue_rx();
ret = platform_device_add(bam_ch[rx_hdr->ch_id].pdev);
@@ -400,6 +405,7 @@
struct tx_pkt_info *info;
unsigned long event_data;
struct list_head *node;
+ unsigned long flags;
if (in_global_reset)
return;
@@ -418,6 +424,9 @@
hdr = (struct bam_mux_hdr *)skb->data;
DBG_INC_WRITE_CNT(skb->data_len);
event_data = (unsigned long)(skb);
+ spin_lock_irqsave(&bam_ch[hdr->ch_id].lock, flags);
+ bam_ch[hdr->ch_id].num_tx_pkts--;
+ spin_unlock_irqrestore(&bam_ch[hdr->ch_id].lock, flags);
if (bam_ch[hdr->ch_id].notify)
bam_ch[hdr->ch_id].notify(
bam_ch[hdr->ch_id].priv, BAM_DMUX_WRITE_DONE,
@@ -449,6 +458,13 @@
pr_err("%s: port not open: %d\n", __func__, bam_ch[id].status);
return -ENODEV;
}
+
+ if (bam_ch[id].use_wm &&
+ (bam_ch[id].num_tx_pkts >= HIGH_WATERMARK)) {
+ spin_unlock_irqrestore(&bam_ch[id].lock, flags);
+ pr_err("%s: watermark exceeded: %d\n", __func__, id);
+ return -EAGAIN;
+ }
spin_unlock_irqrestore(&bam_ch[id].lock, flags);
read_lock(&ul_wakeup_lock);
@@ -520,6 +536,10 @@
DBG_INC_TX_SPS_FAILURE_CNT();
spin_unlock(&bam_tx_pool_spinlock);
kfree(pkt);
+ } else {
+ spin_lock_irqsave(&bam_ch[id].lock, flags);
+ bam_ch[id].num_tx_pkts++;
+ spin_unlock_irqrestore(&bam_ch[id].lock, flags);
}
ul_packet_written = 1;
read_unlock(&ul_wakeup_lock);
@@ -578,6 +598,8 @@
bam_ch[id].notify = notify;
bam_ch[id].priv = priv;
bam_ch[id].status |= BAM_CH_LOCAL_OPEN;
+ bam_ch[id].num_tx_pkts = 0;
+ bam_ch[id].use_wm = 0;
spin_unlock_irqrestore(&bam_ch[id].lock, flags);
read_lock(&ul_wakeup_lock);
@@ -655,6 +677,47 @@
return rc;
}
+int msm_bam_dmux_is_ch_full(uint32_t id)
+{
+ unsigned long flags;
+ int ret;
+
+ if (id >= BAM_DMUX_NUM_CHANNELS)
+ return -EINVAL;
+
+ spin_lock_irqsave(&bam_ch[id].lock, flags);
+ bam_ch[id].use_wm = 1;
+ ret = bam_ch[id].num_tx_pkts >= HIGH_WATERMARK;
+ DBG("%s: ch %d num tx pkts=%d, HWM=%d\n", __func__,
+ id, bam_ch[id].num_tx_pkts, ret);
+ if (!bam_ch_is_local_open(id)) {
+ ret = -ENODEV;
+ pr_err("%s: port not open: %d\n", __func__, bam_ch[id].status);
+ }
+ spin_unlock_irqrestore(&bam_ch[id].lock, flags);
+
+ return ret;
+}
+
+int msm_bam_dmux_is_ch_low(uint32_t id)
+{
+ int ret;
+
+ if (id >= BAM_DMUX_NUM_CHANNELS)
+ return -EINVAL;
+
+ bam_ch[id].use_wm = 1;
+ ret = bam_ch[id].num_tx_pkts <= LOW_WATERMARK;
+ DBG("%s: ch %d num tx pkts=%d, LWM=%d\n", __func__,
+ id, bam_ch[id].num_tx_pkts, ret);
+ if (!bam_ch_is_local_open(id)) {
+ ret = -ENODEV;
+ pr_err("%s: port not open: %d\n", __func__, bam_ch[id].status);
+ }
+
+ return ret;
+}
+
static void rx_timer_work_func(struct work_struct *work)
{
struct sps_iovec iov;
@@ -1034,6 +1097,7 @@
for (i = 0; i < BAM_DMUX_NUM_CHANNELS; ++i) {
temp_remote_status = bam_ch_is_remote_open(i);
bam_ch[i].status &= ~BAM_CH_REMOTE_OPEN;
+ bam_ch[i].num_tx_pkts = 0;
if (bam_ch_is_local_open(i))
bam_ch[i].status |= BAM_CH_IN_RESET;
if (temp_remote_status) {