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author | luigi <luigi@FreeBSD.org> | 2001-12-14 23:25:58 +0000 |
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committer | luigi <luigi@FreeBSD.org> | 2001-12-14 23:25:58 +0000 |
commit | 4f7be302eda30f4b54d2d0f02ed9078e1bfbf8b0 (patch) | |
tree | a3a033fbe4ced0f9c9a680608a8fc39e89099c9c /sys/conf | |
parent | 7c495473b76bfe054d19aada7e6ea84dbe3b3136 (diff) | |
download | FreeBSD-src-4f7be302eda30f4b54d2d0f02ed9078e1bfbf8b0.zip FreeBSD-src-4f7be302eda30f4b54d2d0f02ed9078e1bfbf8b0.tar.gz |
Clarify the comments related to DUMMYNET and HZ
MFC after: 3 days
Diffstat (limited to 'sys/conf')
-rw-r--r-- | sys/conf/NOTES | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/sys/conf/NOTES b/sys/conf/NOTES index cbf8f9a..3fd76ef 100644 --- a/sys/conf/NOTES +++ b/sys/conf/NOTES @@ -638,9 +638,13 @@ options ACCEPT_FILTER_HTTP options TCP_DROP_SYNFIN #drop TCP packets with SYN+FIN # DUMMYNET enables the "dummynet" bandwidth limiter. You need -# IPFIREWALL as well. See the dummynet(4) manpage for more info. +# IPFIREWALL as well. See the dummynet(4) and ipfw(8) manpages for more info. +# When you run DUMMYNET it is advisable to also have "options HZ=1000" +# to achieve a smoother scheduling of the traffic. +# # BRIDGE enables bridging between ethernet cards -- see bridge(4). -# You can use IPFIREWALL and dummynet together with bridging. +# You can use IPFIREWALL and DUMMYNET together with bridging. +# options DUMMYNET options BRIDGE @@ -832,11 +836,12 @@ options _KPOSIX_VERSION=199309L # CLOCK OPTIONS # The granularity of operation is controlled by the kernel option HZ whose -# default value (100) means a granularity of 10ms. For an accurate simulation -# of high data rates it might be necessary to reduce the timer granularity to -# 1ms or less. Consider, however, that some interfaces using programmed I/O -# may require a considerable time to output packets. So, reducing the -# granularity too much might actually cause ticks to be missed thus reducing +# default value (100) means a granularity of 10ms (1s/HZ). +# Some subsystems, such as DUMMYNET, might benefit from a smaller +# granularity such as 1ms or less, for a smoother scheduling of packets. +# Consider, however, that reducing the granularity too much might +# cause excessive overhead in clock interrupt processing, +# potentially causing ticks to be missed and thus actually reducing # the accuracy of operation. options HZ=100 |