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authorBen Hutchings <bhutchings@solarflare.com>2011-08-15 14:09:22 +0000
committerDavid S. Miller <davem@davemloft.net>2011-08-16 16:36:15 -0700
commita27fc96b0317b732b68b5f781bbdeb56ab5082a8 (patch)
treef52b25ab7a0005f0bd1da684873c8de8c1f3b7cf
parentacf42a2a575777681fee45ed59d7140be38e9142 (diff)
downloadtalos-op-linux-a27fc96b0317b732b68b5f781bbdeb56ab5082a8.tar.gz
talos-op-linux-a27fc96b0317b732b68b5f781bbdeb56ab5082a8.zip
ethtool: Note common alternate exit condition for interrupt coalescing
Many implementations ignore the value of max_frames and do not treat usecs == 0 as special. Document this as deprecated. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/ethtool.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 42378b34ae8f..3829712ccc05 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -173,6 +173,12 @@ struct ethtool_eeprom {
* would cause interrupts to never be generated. To disable
* coalescing, set usecs = 0 and max_frames = 1.
*
+ * Some implementations ignore the value of max_frames and use the
+ * condition:
+ * time_since_first_completion >= usecs
+ * This is deprecated. Drivers for hardware that does not support
+ * counting completions should validate that max_frames == !rx_usecs.
+ *
* Adaptive RX/TX coalescing is an algorithm implemented by some
* drivers to improve latency under low packet rates and improve
* throughput under high packet rates. Some drivers only implement
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