[libvirt-users] minor swap issue ....

[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 at 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 at 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 at Q6600, test, 10:14:09am] 3385 %


on the VM, logged in through a different terminal window:


[wam at centos-5, CFD, 10:09:14am] 6507 %
[wam at 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 at 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.