All,

I ran into some problems when I tried to run the 3.2.12 version of the 
kernel and traced them down to starting for my system in 2.6.33.1. I was 
wondering if anyone here had thoughts? I've followed the guidelines for 
submitting a bug report so that I don't miss anything obvious in this 
first go.

Swapon very slow with swapfiles.

After upgrading the kernel my swap file loads very slowly, while a swap 
partition is unaffected. With the newer kernel (2.6.33.1) I get

# time swapon -v /var/swapfile
swapon on /var/swapfile
swapon: /var/swapfile: found swap signature: version 1, page-size 4, 
same byte order
swapon: /var/swapfile: pagesize=4096, swapsize=6442450944, 
devsize=6442450944

real    4m35.355s
user    0m0.001s
sys    0m1.786s

while with the older kernel (2.6.32.27) I get
# time swapon -v /var/swapfile
swapon on /var/swapfile
swapon: /var/swapfile: found swap signature: version 1, page-size 4, 
same byte order
swapon: /var/swapfile: pagesize=4096, swapsize=6442450944, 
devsize=6442450944

real    0m1.158s
user    0m0.000s
sys     0m0.876s

this stays true even for new swapfiles I create with dd.

the file is on an OCZ Vertex2 SSD. Based on the testing I've done it 
doesn't seem to be a problem with the loopback driver, or the swap 
driver so I'm confused. Also the wall time is at least roughly accurate 
at 4 minutes 35 seconds even though there is under 2 seconds of system 
time involved. During the entire time that the the command is running 
the HDD activity light is lit.

Keywords: swapfile

The precise version of the kernel I'm running is Linux gatita 2.6.33.1 
#1 SMP Wed Mar 21 20:12:58 MDT 2012 x86_64 AMD Phenom(tm) II X4 925 
Processor AuthenticAMD GNU/Linux

Kernel 2.6.32.27 did not exhibit this behavior

The running environment is attached in the plaint text file environment

I was unable to get kernel version 2.6.33 to boot with the same .config 
file that is attached (error message about trying to kill init before 
logging even started) so I can't tell for sure the exact version this 
problem was introduced in. I expect that it was introduced in 2.6.33, 
but can't be sure.

Unfortunately I can't give instructions on how to recreate this on 
another computer as I have documented cases of swap turning on as 
expected when I asked around the gentoo forums for help.

Can anyone point me to a resource that I missed in my search or suggest 
anything to go forward?



Additionally with the new kernel I have

gatita ~ # time swapon -v /dev/sdb5
swapon on /dev/sdb5
swapon: /dev/sdb5: found swap signature: version 1, page-size 4, same 
byte order
swapon: /dev/sdb5: pagesize=4096, swapsize=2006933504, devsize=2006936064

real    0m0.024s
user    0m0.000s
sys     0m0.004s
gatita ~ # time mount /mnt/tmp/drive.drv /mnt/data/

real    0m0.198s
user    0m0.000s
sys     0m0.136s


while with the old kernel I have

gatita ~ # time swapon -v /dev/sdb5
swapon on /dev/sdb5
swapon: /dev/sdb5: found swap signature: version 1, page-size 4, same 
byte order
swapon: /dev/sdb5: pagesize=4096, swapsize=2006933504, devsize=2006936064

real    0m0.028s
user    0m0.000s
sys    0m0.004s
gatita ~ # time mount -o loop /mnt/tmp/drive.drv /mnt/data/

real    0m0.069s
user    0m0.001s
sys    0m0.005s

-- 
Jason Mattax
575-418-1791
jmattax@storytotell.org