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Compcache 0.6 stats corruption on Android #34

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
I've built the multiple_rzs branch from HG (as of yesterday) for Android
(2.6.29-msm kernel) and I'm not getting good results with it.  The patched
up version of 0.5 is working fine, though.

Dmesg from module load, "rzscontrol /dev/block/ramzswap0 --init", and
swapon (no backing device used)..

<6>[  999.533630] ramzswap: NUM_DEVICES not specified. Using default: 1
<6>[  999.540588] ramzswap: Creating 1 devices ...
<6>[ 1222.411437] ramzswap: disk size not provided. You can use disksize_kb
module param to specify size.
<6>[ 1222.411468] Using default: (25% of RAM).
<6>[ 1222.427246] ramzswap: disk size set to 24468 kB
<6>[ 1272.504028] Adding 24464k swap on /dev/block/ramzswap0.  Priority:-1
extents:1 across:24464k SSD

And the stats look like this:

# rzscontrol /dev/block/ramzswap0  --stats
DiskSize:      37624 kB
NumReads:        171
NumWrites:       113
FailedReads:           0
FailedWrites:        391
InvalidIO:         0
PagesDiscard:          0
ZeroPages:         0
GoodCompress:          0 %
NoCompress:        0 %
PagesStored:           0
PagesUsed:         0
OrigDataSize:          0 kB
ComprDataSize:         0 kB
MemUsedTotal:          9 kB

So it does not appear to be compressing anything.  Any help is appreciated!

Original issue reported on code.google.com by steve.ko...@gmail.com on 22 Jul 2009 at 2:02

GoogleCodeExporter commented 9 years ago 
I'm seeing strange results on my device as well.

<6>[ 8070.839508] ramzswap: disk size not provided. You can use disksize_kb 
module
param to specify size.
<6>[ 8070.839569] Using default: (25% of RAM).
<6>[ 8070.855102] ramzswap: disk size set to 24468 kB
<6>[ 8085.402343] Adding 24464k swap on /dev/ramzswap0.  Priority:-1 extents:1
across:24464k SSD

# rzscontrol /dev/ramzswap0 -s
DiskSize:   25055232 kB
NumReads:       2204
NumWrites:       192
FailedReads:           0
FailedWrites:       2321
InvalidIO:         0
PagesDiscard:          0
ZeroPages:         0
GoodCompress:          0 %
NoCompress:        0 %
PagesStored:           0
PagesUsed:         0
OrigDataSize:          0 kB
ComprDataSize:         0 kB
MemUsedTotal:        117 kB

# free
              total         used         free       shared      buffers
  Mem:        97876        96280         1596            0          164
 Swap:        24464         2972        21492
Total:       122340        99252        23088
# cat /proc/swaps
Filename                Type        Size    Used    Priority
/dev/ramzswap0                          partition   24464   3140    -1

Original comment by cgaik...@gmail.com on 22 Jul 2009 at 2:08

GoogleCodeExporter commented 9 years ago 
Please provide following data:
 - kernel logs
 - kernel config
 - /proc/meminfo
 - /proc/cpuinfo

Original comment by nitingupta910@gmail.com on 22 Jul 2009 at 2:11

GoogleCodeExporter commented 9 years ago 
I'm puzzled. Can you try 0.6pre2 so I know what code I should be looking at? 
Maybe I
just committed some junk when you pulled it.

Original comment by nitingupta910@gmail.com on 22 Jul 2009 at 2:23

GoogleCodeExporter commented 9 years ago 
Here ya go.  This is with 0.6pre2.  Stats looks the same as what I had pasted 
earlier
running off the HG branch.  The DiskSize output seems a bit odd too.

Original comment by cgaik...@gmail.com on 22 Jul 2009 at 2:41

Attachments:

GoogleCodeExporter commented 9 years ago 
Just now I pushed changes that *may* solve this issue. Can you try this?
During compilation, You should get this warning: "Compiling on ARM".

Original comment by nitingupta910@gmail.com on 22 Jul 2009 at 5:01

GoogleCodeExporter commented 9 years ago 
I'm still seeing the same behavior.  Here are the other warnings during 
compile, not
sure if they'd be relevant..

  CC [M]  /home/chris/android/src/compcache/ramzswap.o
/home/chris/android/src/compcache/ramzswap.c:35:2: warning: #warning "Compiling 
on ARM"
/home/chris/android/src/compcache/ramzswap.c: In function 
'ramzswap_set_disksize':
/home/chris/android/src/compcache/ramzswap.c:1237: warning: format '%lu' 
expects type
'long unsigned int', but argument 3 has type 'size_t'
/home/chris/android/src/compcache/ramzswap.c: In function 
'ramzswap_set_memlimit':
/home/chris/android/src/compcache/ramzswap.c:1284: warning: format '%lu' 
expects type
'long unsigned int', but argument 3 has type 'size_t'

Original comment by cgaik...@gmail.com on 22 Jul 2009 at 8:58

GoogleCodeExporter commented 9 years ago 
Fresh pull from hg and I get the same behavior as well.

Original comment by steve.ko...@gmail.com on 22 Jul 2009 at 10:48

GoogleCodeExporter commented 9 years ago 
> Fresh pull from hg and I get the same behavior as well.

I had inserted warning/error messages for every case where write failure can 
happen.
So, you must now have one of these messages in you logs. Can you upload logs 
from
this latest test? And also the output of 'rzscontrol /dev/ramzswap0 --stats'.

If there are still no warn/error messages in logs then it might be possible that
somehow stats being reported are simply junk and compcache is actually working 
fine.
I have this suspicion since "DiskSize" stat is showing weired values too.

Original comment by nitingupta910@gmail.com on 23 Jul 2009 at 2:34

GoogleCodeExporter commented 9 years ago 
I found 1 issue with stats. The stats structure is 256 bytes which was being
allocated on kernel stack! This can cause stats corruption. Now it is 
dynamically
allocated.

Original comment by nitingupta910@gmail.com on 23 Jul 2009 at 3:33

GoogleCodeExporter commented 9 years ago 
Can you please try test version attached. Fixes include:
 - Alloc ioctl stats dynamically.
 - Flush cache for all uncompressed and zero filled pages too.

Original comment by nitingupta910@gmail.com on 23 Jul 2009 at 10:21

Attachments:

GoogleCodeExporter commented 9 years ago 
Here's what I got with the 0.6_arm_test1.  Not seeing any of the 
warnings/errors in
the logs for write failures either.

# ./rzscontrol /dev/ramzswap0 --stats
DiskSize:   25055232 kB
NumReads:        122
NumWrites:         3
FailedReads:           0
FailedWrites:        132
InvalidIO:         0
PagesDiscard:          0
ZeroPages:         0
GoodCompress:          0 %
NoCompress:        0 %
PagesStored:           0
PagesUsed:         0
OrigDataSize:          0 kB
ComprDataSize:         0 kB
MemUsedTotal:          9 kB

Original comment by cgaik...@gmail.com on 23 Jul 2009 at 3:05

Attachments:

GoogleCodeExporter commented 9 years ago 
Extremely weird. If swap writes were actually failing then kernel will throw 
out tons
of err/warnings - but we are not getting any such messages.

Put some memory load so it starts swapping to ramzswap. See if things crash. 
Also
observer output of /proc/swaps - this would give some hint if rzs if actually 
working
or not.

But how can we get junk in stats? I don't know yet - it all works fine on 
x86/x64.
Your output shows DiskSize in bytes while we print it out in KB. This is just so
weird since its not some arbitrary junk either -- how can it suddenly "forget"
conversion to KB??

Original comment by nitingupta910@gmail.com on 23 Jul 2009 at 3:24

GoogleCodeExporter commented 9 years ago 
haha I agree.  It seems very odd and so far nothing is crashing.  Swap does 
seem to
fill up more quickly but that's just a guess.  It's not filling fast enough to 
say
for sure either way.  I'll keep an eye on it and run some performance tests.  

Steve's output showed the kilobytes instead of bytes, though.  What could I 
possibly
do differently that would cause that?

Original comment by cgaik...@gmail.com on 23 Jul 2009 at 3:29

GoogleCodeExporter commented 9 years ago 
Alright... running from a fresh ramzswap each time, so 0 used.  Ran mmap001
(http://www.arm.linux.org.uk/developer/stresstests.php) until it finished its 
tests.
 Here's the output at the end:

With 0.6
Filename                Type        Size    Used    Priority
/dev/ramzswap0                          partition   24464   24392   -1

With 0.5.3:
Filename                Type        Size    Used    Priority
/dev/ramzswap0                          partition   24464   16984   -1

Original comment by cgaik...@gmail.com on 23 Jul 2009 at 3:55

GoogleCodeExporter commented 9 years ago 
I don't know why more swap is used with 0.6 but at least its seems to be working
fine. This narrows down the issue to stats corruption.

Original comment by nitingupta910@gmail.com on 23 Jul 2009 at 4:10

GoogleCodeExporter commented 9 years ago 
I guess my only concern was that the app was consuming the same amount of 
memory both
times and that I was seeing compression with .5 and no compression with .6.  
I'll
have to do a little more digging in what the app is doing with memory though.  I
don't even know if that's a possibility that ramz could be storing uncompressed 
pages.

Original comment by cgaik...@gmail.com on 23 Jul 2009 at 5:55

GoogleCodeExporter commented 9 years ago 
Can you please try test version attached? It makes stats structure packed and
aligned(4). It also prints out stats to kern log. If stats are correct in logs 
but
not in direct output then it must be copy_to_user() which corrupting stats 
structure.

Thanks,
Nitin

Original comment by nitingupta910@gmail.com on 24 Jul 2009 at 4:35

Attachments:

GoogleCodeExporter commented 9 years ago 
Looks like you were right.  The --stats output is still bad but here's the 
output
from the kernel logs:

<6>[54161.862152] DiskSize:    24468 kB
<6>[54161.865753] NumReads:      157
<6>[54161.865783] NumWrites:        1627
<6>[54161.865783] FailedReads:         0
<6>[54161.865783] FailedWrites:        0
<6>[54161.865783] InvalidIO:           0
<6>[54161.865783] PagesDiscard:        0
<6>[54161.865814] ZeroPages:          68
<6>[54161.865814] GoodCompress:       65 %
<6>[54161.865814] NoCompress:          5 %
<6>[54161.865814] PagesStored:      1559
<6>[54161.865844] PagesUsed:         626
<6>[54161.865844] OrigDataSize:     6236 kB
<6>[54161.865844] ComprDataSize:        2404 kB
<6>[54161.865844] MemUsedTotal:     2504 kB

Original comment by cgaik...@gmail.com on 24 Jul 2009 at 5:16

GoogleCodeExporter commented 9 years ago

Original comment by nitingupta910@gmail.com on 30 Jul 2009 at 2:58

GoogleCodeExporter commented 9 years ago 
Another try:

I just submitted change to now allocate rzscontrol stats on heap. This *might*
resolve the issue if allocation on stack was giving us unaligned pointer.

Please try latest commit. It prints some debug messages on stdout - so, please 
post
output of rzscontrol and also the kernel log.

Original comment by nitingupta910@gmail.com on 30 Jul 2009 at 5:44

GoogleCodeExporter commented 9 years ago 
/system/lib/modules # rzscontrol /dev/block/ramzswap0 --stats
debug: ret=0, stats_addr=0xb008, stats_sz=252
debug: 38368, 0, 0, 25051136
DiskSize:          0 kB
NumReads:          0
NumWrites:        52
FailedReads:           0
FailedWrites:        422
InvalidIO:         0
PagesDiscard:          0
ZeroPages:         0
GoodCompress:          0 %
NoCompress:        0 %
PagesStored:           0
PagesUsed:         0
OrigDataSize:          0 kB
ComprDataSize:         0 kB
MemUsedTotal:         50 kB

Original comment by steve.ko...@gmail.com on 31 Jul 2009 at 5:29

GoogleCodeExporter commented 9 years ago 
[deleted comment]
GoogleCodeExporter commented 9 years ago 
[deleted comment]
GoogleCodeExporter commented 9 years ago 
I can now reproduce this issue on qemu ARM emulator! Lets hope we'll find this 
fix soon.

Original comment by nitingupta910@gmail.com on 31 Jul 2009 at 2:45

GoogleCodeExporter commented 9 years ago 
Now it works correctly, at least on QEMU ARM emulator. Can you please confirm 
if it
works correctly on actual h/w too? Thanks!

Output from emulator:

DiskSize:          31608 kB
NumReads:         170544
NumWrites:        170956
FailedReads:           0
FailedWrites:          0
InvalidIO:             0
PagesDiscard:      64491
ZeroPages:           190
GoodCompress:         98 %
NoCompress:            0 %
PagesStored:        7711
PagesUsed:           255
OrigDataSize:      30844 kB
ComprDataSize:       947 kB
MemUsedTotal:       1020 kB

Original comment by nitingupta910@gmail.com on 2 Aug 2009 at 6:18

GoogleCodeExporter commented 9 years ago 
Working great on an actual G1:

/ # rzscontrol /dev/block/ramzswap0 -s
DiskSize:      24464 kB
NumReads:        102
NumWrites:       557
FailedReads:           0
FailedWrites:          0
InvalidIO:         0
PagesDiscard:          0
ZeroPages:        52
GoodCompress:         87 %
NoCompress:        1 %
PagesStored:         505
PagesUsed:       132
OrigDataSize:       2020 kB
ComprDataSize:       517 kB
MemUsedTotal:        528 kB

Thanks!!!!

Original comment by steve.ko...@gmail.com on 3 Aug 2009 at 5:01

GoogleCodeExporter commented 9 years ago

Original comment by nitingupta910@gmail.com on 3 Aug 2009 at 5:15