[libvirt-users] minor swap issue ....
by William A. Mahaffey III
.... I have a CentOS 5.n VM running on a Fedora 14 server/host,
installed using virt-manager, pretty plain vanilla. I use it to compile
binaries to run under RHEL/CentOS 5.n OS. I occasionally notice that
when the VM gets paged out by the server, it takes several minutes to
get it back in :-/ (see below).
On the host, logged in to a shell through a terminal window, this A.M.:
[wam@Q6600, test, 10:09:08am] 3384 % /sbin/swapon -s ; free -m ; uname
-a ; /sbin/hwclock -r ; date
Filename Type Size Used
Priority
/dev/md2 partition 16773116
1967524 -1
total used free shared buffers cached
Mem: 7993 7932 61 0 11 7176
-/+ buffers/cache: 744 7249
Swap: 16379 1921 14458
Linux Q6600 2.6.35.14-106.fc14.x86_64 #1 SMP Wed Nov 23 13:07:52 UTC
2011 x86_64 x86_64 x86_64 GNU/Linux
Tue Sep 25 10:09:11 2012 -0.890900 seconds
Tue Sep 25 10:09:11 CDT 2012
[wam@Q6600, test, 10:09:11am] 3385 % /sbin/swapon -s ; free -m ; uname
-a ; /sbin/hwclock -r ; date
Filename Type Size Used
Priority
/dev/md2 partition 16773116
1415136 -1
total used free shared buffers cached
Mem: 7993 7939 54 0 12 6358
-/+ buffers/cache: 1568 6425
Swap: 16379 1381 14998
Linux Q6600 2.6.35.14-106.fc14.x86_64 #1 SMP Wed Nov 23 13:07:52 UTC
2011 x86_64 x86_64 x86_64 GNU/Linux
Tue Sep 25 10:14:09 2012 -0.281487 seconds
Tue Sep 25 10:14:09 CDT 2012
[wam@Q6600, test, 10:14:09am] 3385 %
on the VM, logged in through a different terminal window:
[wam@centos-5, CFD, 10:09:14am] 6507 %
[wam@centos-5, CFD, 10:09:14am] 6507 % ( cd ../Utils/ ; make extra ) ; cd .
make[1]: Entering directory `/home/wam/dev/CFD/Utils'
make[2]: Entering directory `/home/wam/dev/CFD/Utils'
/home/wam/dev/CFD/Utils/../lib/R4/SSE2/libutils.a up to date.
make[2]: Leaving directory `/home/wam/dev/CFD/Utils'
make[2]: Entering directory `/home/wam/dev/CFD/Utils'
/home/wam/dev/CFD/Utils/../lib/R8/SSE2/libutils.a up to date.
make[2]: Leaving directory `/home/wam/dev/CFD/Utils'
make[1]: Leaving directory `/home/wam/dev/CFD/Utils'
cd /net/cube/home/wam/V8/Cnx/test/junk/cart/unstaggered/bfc/utils; icc
-c -DNDEBUG -DUNDER_SCORE_SYS -DLOSE_GAMMAL -gcc-version=340
-gcc-name=gcc34 -fabi-version=2 -I
/net/cube/home/wam/V8/Cnx/test/junk/cart/unstaggered/bfc/include
-wd138,167,186,266,279,880,1418,1419,2330,2331 -O3 -ip -opt-prefetch
-parallel -opt-multi-version-aggressive -xSSE2 -DP64_BIT test.cpp
cd /net/cube/home/wam/V8/Cnx/test/junk/cart/unstaggered/bfc/utils; icc
-o /home/wam/bin/checkout -parallel -mkl=parallel -Wl,-s test.o -L
/home/wam/dev/CFD/Utils/../lib/R4/SSE2 -Wl,--start-group -lutils -lMemIO
-Wl,--end-group && \rm -f test.o
Done with extra.
[wam@centos-5, CFD, 10:12:36am] 6508 %
i.e. it took 3+ min. to get back to the prompt for this command (usually
about 5 sec.) .... This isn't a show-stopped by any means, but it is
irritating. From the timestamps & data from the host & guest, apparently
all of that was used up swapping the guest back in. Is there any way to
either prioritize the VM to not get swapped out, or preferentially
swapped back in :-) ? TIA for any pointers ....
--
William A. Mahaffey III
----------------------------------------------------------------------
"The M1 Garand is without doubt the finest implement of war
ever devised by man."
-- Gen. George S. Patton Jr.