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authorBen Hutchings <bhutchings@solarflare.com>2011-08-15 14:07:47 +0000
committerDavid S. Miller <davem@davemloft.net>2011-08-16 16:36:14 -0700
commit2d7c79390eccd743a643db3fa577f4837e7f2b85 (patch)
tree9c13001aac43a3f3de9e9d60778968faf56a92b5
parentethtool: Specify what kind of coalescing struct ethtool_coalesce covers (diff)
downloadlinux-dev-2d7c79390eccd743a643db3fa577f4837e7f2b85.tar.xz
linux-dev-2d7c79390eccd743a643db3fa577f4837e7f2b85.zip
ethtool: Correct description of 'max_coalesced_frames' fields
The current descriptions state that these fields specify 'How many packets to delay ... after a packet ...' which implies that the hardware should wait for (max_coalesced_frames + 1) completions before generating an interrupt. It is also stated that setting both this field and the corresponding 'coalesce_usecs' field to 0 is invalid. Together, this implies that the hardware must always be configured to delay a completion IRQ for at least 1 usec or 1 more completion. I believe that the addition of 1 is not intended, and David Miller confirms that the original implementation (in tg3) does not do this. Clarify the descriptions of these fields to avoid this interpretation. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/ethtool.h26
1 files changed, 13 insertions, 13 deletions
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 71d45a199f96..18059ca41f09 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -122,8 +122,8 @@ struct ethtool_eeprom {
* @cmd: ETHTOOL_{G,S}COALESCE
* @rx_coalesce_usecs: How many usecs to delay an RX interrupt after
* a packet arrives. If 0, only @rx_max_coalesced_frames is used.
- * @rx_max_coalesced_frames: How many packets to delay an RX interrupt
- * after a packet arrives. If 0, only @rx_coalesce_usecs is used.
+ * @rx_max_coalesced_frames: Maximum number of packets to receive
+ * before an RX interrupt. If 0, only @rx_coalesce_usecs is used.
* @rx_coalesce_usecs_irq: Same as @rx_coalesce_usecs, except that
* this value applies while an IRQ is being serviced by the host.
* @rx_max_coalesced_frames_irq: Same as @rx_max_coalesced_frames,
@@ -132,9 +132,9 @@ struct ethtool_eeprom {
* @tx_coalesce_usecs: How many usecs to delay a TX interrupt after
* a packet is sent. If 0, only @tx_max_coalesced_frames
* is used.
- * @tx_max_coalesced_frames: How many packets to delay a TX interrupt
- * after a packet is sent. If 0, only @tx_coalesce_usecs is
- * used.
+ * @tx_max_coalesced_frames: Maximum number of packets to be sent
+ * before a TX interrupt. If 0, only @tx_coalesce_usecs is
+ * used.
* @tx_coalesce_usecs_irq: Same as @tx_coalesce_usecs, except that
* this value applies while an IRQ is being serviced by the host.
* @tx_max_coalesced_frames_irq: Same as @tx_max_coalesced_frames,
@@ -149,21 +149,21 @@ struct ethtool_eeprom {
* @pkt_rate_low: Threshold for low packet rate (packets per second).
* @rx_coalesce_usecs_low: How many usecs to delay an RX interrupt after
* a packet arrives, when the packet rate is below @pkt_rate_low.
- * @rx_max_coalesced_frames_low: How many packets to delay an RX interrupt
- * after a packet arrives, when the packet rate is below @pkt_rate_low.
+ * @rx_max_coalesced_frames_low: Maximum number of packets to be received
+ * before an RX interrupt, when the packet rate is below @pkt_rate_low.
* @tx_coalesce_usecs_low: How many usecs to delay a TX interrupt after
* a packet is sent, when the packet rate is below @pkt_rate_low.
- * @tx_max_coalesced_frames_low: How many packets to delay a TX interrupt
- * after a packet is sent, when the packet rate is below @pkt_rate_low.
+ * @tx_max_coalesced_frames_low: Maximum nuumber of packets to be sent before
+ * a TX interrupt, when the packet rate is below @pkt_rate_low.
* @pkt_rate_high: Threshold for high packet rate (packets per second).
* @rx_coalesce_usecs_high: How many usecs to delay an RX interrupt after
* a packet arrives, when the packet rate is above @pkt_rate_high.
- * @rx_max_coalesced_frames_high: How many packets to delay an RX interrupt
- * after a packet arrives, when the packet rate is above @pkt_rate_high.
+ * @rx_max_coalesced_frames_high: Maximum number of packets to be received
+ * before an RX interrupt, when the packet rate is above @pkt_rate_high.
* @tx_coalesce_usecs_high: How many usecs to delay a TX interrupt after
* a packet is sent, when the packet rate is above @pkt_rate_high.
- * @tx_max_coalesced_frames_high: How many packets to delay a TX interrupt
- * after a packet is sent, when the packet rate is above @pkt_rate_high.
+ * @tx_max_coalesced_frames_high: Maximum number of packets to be sent before
+ * a TX interrupt, when the packet rate is above @pkt_rate_high.
* @rate_sample_interval: How often to do adaptive coalescing packet rate
* sampling, measured in seconds. Must not be zero.
*