[PATCH 6/6] staging: unisys: visornic - consolidate+simplify xmit watermark checks
Benjamin Romer
benjamin.romer at unisys.com
Tue Jul 28 16:29:11 UTC 2015
From: Tim Sell <Timothy.Sell at unisys.com>
The code that tests for high and low xmit watermarks was consolidatedand
simplified. The output behavior should be identical, with the exception
of an off-by-one error being corrected in the tests done when the counters
overflowed.
Signed-off-by: Tim Sell <Timothy.Sell at unisys.com>
Signed-off-by: Benjamin Romer <benjamin.romer at unisys.com>
---
drivers/staging/unisys/visornic/visornic_main.c | 114 ++++++++++++++++--------
1 file changed, 75 insertions(+), 39 deletions(-)
diff --git a/drivers/staging/unisys/visornic/visornic_main.c b/drivers/staging/unisys/visornic/visornic_main.c
index a2dac0b..3740c8f 100644
--- a/drivers/staging/unisys/visornic/visornic_main.c
+++ b/drivers/staging/unisys/visornic/visornic_main.c
@@ -136,15 +136,16 @@ struct visornic_devdata {
atomic_t num_rcvbuf_in_iovm;
unsigned long alloc_failed_in_if_needed_cnt;
unsigned long alloc_failed_in_repost_rtn_cnt;
- int max_outstanding_net_xmits; /* absolute max number of outstanding
- * xmits - should never hit this
- */
- int upper_threshold_net_xmits; /* high water mark for calling
- * netif_stop_queue()
- */
- int lower_threshold_net_xmits; /* high water mark for calling
- * netif_wake_queue()
- */
+ unsigned long max_outstanding_net_xmits; /* absolute max number of
+ * outstanding xmits - should
+ * never hit this
+ */
+ unsigned long upper_threshold_net_xmits; /* high water mark for
+ * calling netif_stop_queue()
+ */
+ unsigned long lower_threshold_net_xmits; /* high water mark for calling
+ * netif_wake_queue()
+ */
struct sk_buff_head xmitbufhead; /* xmitbufhead is the head of the
* xmit buffer list that have been
* sent to the IOPART end
@@ -784,6 +785,53 @@ visornic_close(struct net_device *netdev)
}
/**
+ * devdata_xmits_outstanding - compute outstanding xmits
+ * @devdata: visornic_devdata for device
+ *
+ * Return value is the number of outstanding xmits.
+ */
+static unsigned long devdata_xmits_outstanding(struct visornic_devdata *devdata)
+{
+ if (devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done)
+ return devdata->chstat.sent_xmit -
+ devdata->chstat.got_xmit_done;
+ else
+ return (ULONG_MAX - devdata->chstat.got_xmit_done
+ + devdata->chstat.sent_xmit + 1);
+}
+
+/**
+ * vnic_hit_high_watermark
+ * @devdata: indicates visornic device we are checking
+ * @high_watermark: max num of unacked xmits we will tolerate,
+ * before we will start throttling
+ *
+ * Returns true iff the number of unacked xmits sent to
+ * the IO partition is >= high_watermark.
+ */
+static inline bool vnic_hit_high_watermark(struct visornic_devdata *devdata,
+ ulong high_watermark)
+{
+ return (devdata_xmits_outstanding(devdata) >= high_watermark);
+}
+
+/**
+ * vnic_hit_low_watermark
+ * @devdata: indicates visornic device we are checking
+ * @low_watermark: we will wait until the num of unacked xmits
+ * drops to this value or lower before we start
+ * transmitting again
+ *
+ * Returns true iff the number of unacked xmits sent to
+ * the IO partition is <= low_watermark.
+ */
+static inline bool vnic_hit_low_watermark(struct visornic_devdata *devdata,
+ ulong low_watermark)
+{
+ return (devdata_xmits_outstanding(devdata) <= low_watermark);
+}
+
+/**
* visornic_xmit - send a packet to the IO Partition
* @skb: Packet to be sent
* @netdev: net device the packet is being sent from
@@ -858,13 +906,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
/* save the pointer to skb -- we'll need it for completion */
cmdrsp->net.buf = skb;
- if (((devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done) &&
- (devdata->chstat.sent_xmit - devdata->chstat.got_xmit_done >=
- devdata->max_outstanding_net_xmits)) ||
- ((devdata->chstat.sent_xmit < devdata->chstat.got_xmit_done) &&
- (ULONG_MAX - devdata->chstat.got_xmit_done +
- devdata->chstat.sent_xmit >=
- devdata->max_outstanding_net_xmits))) {
+ if (vnic_hit_high_watermark(devdata,
+ devdata->max_outstanding_net_xmits)) {
/* too many NET_XMITs queued over to IOVM - need to wait
*/
devdata->chstat.reject_count++;
@@ -946,13 +989,8 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
/* check to see if we have hit the high watermark for
* netif_stop_queue()
*/
- if (((devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done) &&
- (devdata->chstat.sent_xmit - devdata->chstat.got_xmit_done >=
- devdata->upper_threshold_net_xmits)) ||
- ((devdata->chstat.sent_xmit < devdata->chstat.got_xmit_done) &&
- (ULONG_MAX - devdata->chstat.got_xmit_done +
- devdata->chstat.sent_xmit >=
- devdata->upper_threshold_net_xmits))) {
+ if (vnic_hit_high_watermark(devdata,
+ devdata->upper_threshold_net_xmits)) {
/* too many NET_XMITs queued over to IOVM - need to wait */
netif_stop_queue(netdev); /* calling stop queue - call
* netif_wake_queue() after lower
@@ -1446,13 +1484,13 @@ static ssize_t info_debugfs_read(struct file *file, char __user *buf,
" num_rcv_bufs = %d\n",
devdata->num_rcv_bufs);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
- " max_oustanding_next_xmits = %d\n",
+ " max_oustanding_next_xmits = %lu\n",
devdata->max_outstanding_net_xmits);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
- " upper_threshold_net_xmits = %d\n",
+ " upper_threshold_net_xmits = %lu\n",
devdata->upper_threshold_net_xmits);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
- " lower_threshold_net_xmits = %d\n",
+ " lower_threshold_net_xmits = %lu\n",
devdata->lower_threshold_net_xmits);
str_pos += scnprintf(vbuf + str_pos, len - str_pos,
" queuefullmsg_logged = %d\n",
@@ -1551,6 +1589,9 @@ static ssize_t info_debugfs_read(struct file *file, char __user *buf,
" netif_queue = %s\n",
netif_queue_stopped(devdata->netdev) ?
"stopped" : "running");
+ str_pos += scnprintf(vbuf + str_pos, len - str_pos,
+ " xmits_outstanding = %lu\n",
+ devdata_xmits_outstanding(devdata));
}
rcu_read_unlock();
bytes_read = simple_read_from_buffer(buf, len, offset, vbuf, str_pos);
@@ -1644,16 +1685,8 @@ service_resp_queue(struct uiscmdrsp *cmdrsp, struct visornic_devdata *devdata)
* the lower watermark for
* netif_wake_queue()
*/
- if (((devdata->chstat.sent_xmit >=
- devdata->chstat.got_xmit_done) &&
- (devdata->chstat.sent_xmit -
- devdata->chstat.got_xmit_done <=
- devdata->lower_threshold_net_xmits)) ||
- ((devdata->chstat.sent_xmit <
- devdata->chstat.got_xmit_done) &&
- (ULONG_MAX - devdata->chstat.got_xmit_done
- + devdata->chstat.sent_xmit <=
- devdata->lower_threshold_net_xmits))) {
+ if (vnic_hit_low_watermark(devdata,
+ devdata->lower_threshold_net_xmits)) {
/* enough NET_XMITs completed
* so can restart netif queue
*/
@@ -1824,12 +1857,15 @@ static int visornic_probe(struct visor_device *dev)
/* set the net_xmit outstanding threshold */
/* always leave two slots open but you should have 3 at a minimum */
+ /* note that max_outstanding_net_xmits must be > 0 */
devdata->max_outstanding_net_xmits =
- max(3, ((devdata->num_rcv_bufs / 3) - 2));
+ max_t(unsigned long, 3, ((devdata->num_rcv_bufs / 3) - 2));
devdata->upper_threshold_net_xmits =
- max(2, devdata->max_outstanding_net_xmits - 1);
+ max_t(unsigned long,
+ 2, (devdata->max_outstanding_net_xmits - 1));
devdata->lower_threshold_net_xmits =
- max(1, devdata->max_outstanding_net_xmits / 2);
+ max_t(unsigned long,
+ 1, (devdata->max_outstanding_net_xmits / 2));
skb_queue_head_init(&devdata->xmitbufhead);
--
2.1.4
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