ia64/linux-2.6.18-xen.hg

view scripts/mkcompile_h @ 897:329ea0ccb344

balloon: try harder to balloon up under memory pressure.

Currently if the balloon driver is unable to increase the guest's
reservation it assumes the failure was due to reaching its full
allocation, gives up on the ballooning operation and records the limit
it reached as the "hard limit". The driver will not try again until
the target is set again (even to the same value).

However it is possible that ballooning has in fact failed due to
memory pressure in the host and therefore it is desirable to keep
attempting to reach the target in case memory becomes available. The
most likely scenario is that some guests are ballooning down while
others are ballooning up and therefore there is temporary memory
pressure while things stabilise. You would not expect a well behaved
toolstack to ask a domain to balloon to more than its allocation nor
would you expect it to deliberately over-commit memory by setting
balloon targets which exceed the total host memory.

This patch drops the concept of a hard limit and causes the balloon
driver to retry increasing the reservation on a timer in the same
manner as when decreasing the reservation.

Also if we partially succeed in increasing the reservation
(i.e. receive less pages than we asked for) then we may as well keep
those pages rather than returning them to Xen.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Fri Jun 05 14:01:20 2009 +0100 (2009-06-05)
parents 831230e53067
children
line source
1 TARGET=$1
2 ARCH=$2
3 SMP=$3
4 PREEMPT=$4
5 CC=$5
7 # If compile.h exists already and we don't own autoconf.h
8 # (i.e. we're not the same user who did make *config), don't
9 # modify compile.h
10 # So "sudo make install" won't change the "compiled by <user>"
11 # do "compiled by root"
13 if [ -r $TARGET -a ! -O include/linux/autoconf.h ]; then
14 echo " SKIPPED $TARGET"
15 exit 0
16 fi
18 # Do not expand names
19 set -f
21 if [ -r .version ]; then
22 VERSION=`cat .version`
23 else
24 VERSION=0
25 echo 0 > .version
26 fi
29 UTS_VERSION="#$VERSION"
30 CONFIG_FLAGS=""
31 if [ -n "$SMP" ] ; then CONFIG_FLAGS="SMP"; fi
32 if [ -n "$PREEMPT" ] ; then CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT"; fi
33 UTS_VERSION="$UTS_VERSION $CONFIG_FLAGS `LC_ALL=C LANG=C date`"
35 # Truncate to maximum length
37 UTS_LEN=64
38 UTS_TRUNCATE="sed -e s/\(.\{1,$UTS_LEN\}\).*/\1/"
40 # Generate a temporary compile.h
42 ( echo /\* This file is auto generated, version $VERSION \*/
43 if [ -n "$CONFIG_FLAGS" ] ; then echo "/* $CONFIG_FLAGS */"; fi
45 echo \#define UTS_MACHINE \"$ARCH\"
47 echo \#define UTS_VERSION \"`echo $UTS_VERSION | $UTS_TRUNCATE`\"
49 echo \#define LINUX_COMPILE_TIME \"`LC_ALL=C LANG=C date +%T`\"
50 echo \#define LINUX_COMPILE_BY \"`whoami`\"
51 echo \#define LINUX_COMPILE_HOST \"`hostname | $UTS_TRUNCATE`\"
53 if [ -x /bin/dnsdomainname ]; then
54 echo \#define LINUX_COMPILE_DOMAIN \"`dnsdomainname | $UTS_TRUNCATE`\"
55 elif [ -x /bin/domainname ]; then
56 echo \#define LINUX_COMPILE_DOMAIN \"`domainname | $UTS_TRUNCATE`\"
57 else
58 echo \#define LINUX_COMPILE_DOMAIN
59 fi
61 echo \#define LINUX_COMPILER \"`$CC -v 2>&1 | tail -n 1`\"
62 ) > .tmpcompile
64 # Only replace the real compile.h if the new one is different,
65 # in order to preserve the timestamp and avoid unnecessary
66 # recompilations.
67 # We don't consider the file changed if only the date/time changed.
68 # A kernel config change will increase the generation number, thus
69 # causing compile.h to be updated (including date/time) due to the
70 # changed comment in the
71 # first line.
73 if [ -r $TARGET ] && \
74 grep -v 'UTS_VERSION\|LINUX_COMPILE_TIME' $TARGET > .tmpver.1 && \
75 grep -v 'UTS_VERSION\|LINUX_COMPILE_TIME' .tmpcompile > .tmpver.2 && \
76 cmp -s .tmpver.1 .tmpver.2; then
77 rm -f .tmpcompile
78 else
79 echo " UPD $TARGET"
80 mv -f .tmpcompile $TARGET
81 fi
82 rm -f .tmpver.1 .tmpver.2