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We can drastically improve boot times on some machines, or BM or VM shapes, if we send DHCP requests in parallel on all interfaces Add ip=single-dhcp as a kernel boot parameter, to send DHCP requests in parallel on all interfaces. Thus, DHCP on each interface is overlapped thereby reducing boot times for multiple interface machines. This can help reduce the boot time by 1 minute per interface. In addition, we may also save another 40 secs delay per interface, if the link on which we try to send DHCP is in DOWN state. This can be reduced by giving the following kernel command line parameter while booting - rd.net.timeout.carrier=<timeout>. Added manpage for ip=single-dhcp with the caveat that it does not apply to Network Manager or SUSE wicked. Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@oracle.com>master
Anjali Kulkarni
4 years ago
committed by
Harald Hoyer
6 changed files with 172 additions and 6 deletions
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#!/bin/sh |
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# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*- |
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# ex: ts=8 sw=4 sts=4 et filetype=sh |
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# |
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PATH=/usr/sbin:/usr/bin:/sbin:/bin |
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# File to start dhclient requests on different interfaces in parallel |
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. /lib/dracut-lib.sh |
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. /lib/net-lib.sh |
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netif=$1 |
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do_vlan=$2 |
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arg=$3 |
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# Run dhclient in parallel |
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do_dhclient() { |
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local _COUNT=0 |
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local _timeout=$(getargs rd.net.timeout.dhcp=) |
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local _DHCPRETRY=$(getargs rd.net.dhcp.retry=) |
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_DHCPRETRY=${_DHCPRETRY:-1} |
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while [ $_COUNT -lt $_DHCPRETRY ]; do |
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info "Starting dhcp for interface $netif" |
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dhclient $arg \ |
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${_timeout:+--timeout $_timeout} \ |
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-q \ |
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-1 \ |
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-cf /etc/dhclient.conf \ |
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-pf /tmp/dhclient.$netif.pid \ |
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-lf /tmp/dhclient.$netif.lease \ |
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$netif & |
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wait $! 2>/dev/null |
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# wait will return the return value of dhclient |
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retv=$? |
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# dhclient and hence wait returned success, 0. |
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if [ $retv -eq 0 ]; then |
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return 0 |
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fi |
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# If dhclient exited before wait was called, or it was killed by |
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# another thread for interface whose DHCP succeeded, then it will not |
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# find the process with that pid and return error code 127. In that |
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# case we need to check if /tmp/dhclient.$netif.lease exists. If it |
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# does, it means dhclient finished executing before wait was called, |
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# and it was successful (return 0). If /tmp/dhclient.$netif.lease |
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# does not exist, then it means dhclient was killed by another thread |
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# or it finished execution but failed dhcp on that interface. |
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if [ $retv -eq 127 ]; then |
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pid=$(cat /tmp/dhclient.$netif.pid) |
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info "PID $pid was not found by wait for $netif" |
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if [ -e /tmp/dhclient.$netif.lease ]; then |
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info "PID $pid not found but DHCP successful on $netif" |
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return 0 |
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fi |
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fi |
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_COUNT=$(($_COUNT+1)) |
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[ $_COUNT -lt $_DHCPRETRY ] && sleep 1 |
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done |
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warn "dhcp for interface $netif failed" |
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# nuke those files since we failed; we might retry dhcp again if it's e.g. |
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# `ip=dhcp,dhcp6` and we check for the PID file earlier |
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rm -f /tmp/dhclient.$netif.{pid,lease} |
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return 1 |
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} |
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do_dhclient |
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ret=$? |
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# setup nameserver |
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for s in "$dns1" "$dns2" $(getargs nameserver); do |
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[ -n "$s" ] || continue |
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echo nameserver $s >> /tmp/net.$netif.resolv.conf |
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done |
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if [ $ret -eq 0 ]; then |
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> /tmp/net.${netif}.up |
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if [ -z "$do_vlan" ] && [ -e /sys/class/net/${netif}/address ]; then |
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> /tmp/net.$(cat /sys/class/net/${netif}/address).up |
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fi |
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# Check if DHCP also suceeded on another interface before this one. |
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# We will always use the first one on which DHCP succeeded, by using |
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# a commom file $IFNETFILE, to synchronize between threads. |
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# Consider the race condition in which multiple threads |
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# corresponding to different interfaces may try to read $IFNETFILE |
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# and find it does not exist; they may all end up thinking they are the |
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# first to succeed (hence more than one thread may end up writing to |
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# $IFNETFILE). To take care of this, instead of checking if $IFNETFILE |
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# exists to determine if we are the first, we create a symbolic link |
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# in $IFNETFILE, pointing to the interface name ($netif), thus storing |
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# the interface name in the link pointer. |
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# Creating a link will fail, if the link already exists, hence kernel |
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# will take care of allowing only first thread to create link, which |
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# takes care of the race condition for us. Subsequent threads will fail. |
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# Also, the link points to the interface name, which will tell us which |
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# interface succeeded. |
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if ln -s $netif $IFNETFILE 2>/dev/null; then |
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intf=$(readlink $IFNETFILE) |
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if [ -e /tmp/dhclient.$intf.lease ]; then |
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info "DHCP successful on interface $intf" |
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# Kill all existing dhclient calls for other interfaces, since we |
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# already got one successful interface |
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npid=$(cat /tmp/dhclient.$netif.pid) |
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pidlist=$(pgrep dhclient) |
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for pid in $pidlist; do |
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[ "$pid" -eq "$npid" ] && continue |
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kill -9 $pid >/dev/null 2>&1 |
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done |
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else |
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echo "ERROR! $IFNETFILE exists but /tmp/dhclient.$intf.lease does not exist!!!" |
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fi |
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else |
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info "DHCP success on $netif, and also on $intf" |
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exit 0 |
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fi |
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exit $ret |
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fi |
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