User:Arete74

Android partionio 4.2

df output

Filesystem             Size   Used   Free   Blksize
/cub/block             395M     0K   395M   4096
/dev                   396M    32K   396M   4096
/mnt/secure            396M     0K   396M   4096
/mnt/asec              396M     0K   396M   4096
/mnt/obb               396M     0K   396M   4096
/system                503M   430M    73M   4096
/tmp                   396M     0K   396M   4096
/data                 1007M   156M   851M   4096
/cache                 314M     5M   309M   4096
/mnt/private            15M     8K    15M   4096
/mnt/sdcard              1G    64K     1G   4096
/mnt/secure/asec: Permission denied

mount output

rootfs / rootfs rw 0 0
devtmpfs /cub/block devtmpfs rw,relatime,size=404692k,nr_inodes=101173,mode=755 0 0
tmpfs /dev tmpfs rw,nosuid,relatime,mode=755 0 0
devpts /dev/pts devpts rw,relatime,mode=600 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,relatime 0 0
none /acct cgroup rw,relatime,cpuacct 0 0
tmpfs /mnt/secure tmpfs rw,relatime,mode=700 0 0
tmpfs /mnt/asec tmpfs rw,relatime,mode=755,gid=1000 0 0
tmpfs /mnt/obb tmpfs rw,relatime,mode=755,gid=1000 0 0
none /dev/cpuctl cgroup rw,relatime,cpu 0 0
/dev/block/system /system ext4 rw,nodev,noatime,nobarrier,data=ordered 0 0
tmpfs /tmp tmpfs rw,relatime,mode=755,gid=1000 0 0
/dev/block/data /data ext4 rw,nosuid,nodev,noatime,journal_checksum,noauto_da_alloc,data=ordered 0 0
/dev/block/cache /cache ext4 rw,nosuid,nodev,noatime,journal_checksum,noauto_da_alloc,data=ordered 0 0
/dev/block/private /mnt/private vfat rw,relatime,fmask=0000,dmask=0000,allow_utime=0022,codepage=cp437,iocharset=ascii,shortname=mixed,errors=continue 0 0
/dev/block/vold/93:80 /mnt/sdcard vfat rw,dirsync,nosuid,nodev,noexec,noatime,uid=1000,gid=1015,fmask=0702,dmask=0702,allow_utime=0020,codepage=cp437,iocharset=ascii,shortname=mixed,utf8,errors=continue 0 0
/dev/block/vold/93:80 /mnt/secure/asec vfat rw,dirsync,nosuid,nodev,noexec,noatime,uid=1000,gid=1015,fmask=0702,dmask=0702,allow_utime=0020,codepage=cp437,iocharset=ascii,shortname=mixed,utf8,errors=continue 0 0
tmpfs /mnt/sdcard/.android_secure tmpfs ro,relatime,size=0k,mode=000 0 0

Optimize sdcard partition

http://docs.pikatech.com/display/DEV/Optimizing+File+System+Parameters+of+SD+card+for+use+on+WARP+V3

http://blogofterje.wordpress.com/2012/01/14/optimizing-fs-on-sd-card/ http://www.thomas-krenn.com/en/wiki/Partition_Alignment#fdisk_from_Version_2.17.1

Determine parameters of SD card

Now we need wish to determine the parameters of the SD card with FlashBench tool. It get be download it and compile it using the following instructions:

git clone git://git.linaro.org/people/arnd/flashbench.git
cd flashbench
make

For determine the parameters execute the flashbench using the following command line:

./flashbench -a /dev/mmcblk0 --blocksize=1024

align 2147483648 pre 1.47ms      on 1.98ms       post 1.68ms     diff 407µs
align 1073741824 pre 1.45ms      on 2ms          post 1.67ms     diff 441µs
align 536870912  pre 1.36ms      on 1.91ms       post 1.68ms     diff 390µs
align 268435456  pre 1.35ms      on 1.91ms       post 1.67ms     diff 393µs
align 134217728  pre 1.36ms      on 1.92ms       post 1.68ms     diff 399µs
align 67108864   pre 1.33ms      on 1.91ms       post 1.69ms     diff 401µs
align 33554432   pre 1.36ms      on 1.93ms       post 1.69ms     diff 401µs
align 16777216   pre 1.36ms      on 1.9ms        post 1.69ms     diff 378µs
align 8388608    pre 1.35ms      on 1.92ms       post 1.68ms     diff 402µs
align 4194304    pre 1.36ms      on 1.91ms       post 1.69ms     diff 388µs
align 2097152    pre 1.6ms       on 1.93ms       post 1.76ms     diff 252µs
align 1048576    pre 1.59ms      on 1.91ms       post 1.74ms     diff 244µs
align 524288     pre 1.56ms      on 1.94ms       post 1.76ms     diff 280µs
align 262144     pre 1.59ms      on 1.92ms       post 1.74ms     diff 258µs
align 131072     pre 1.55ms      on 1.93ms       post 1.74ms     diff 283µs
align 65536      pre 1.59ms      on 1.92ms       post 1.73ms     diff 265µs
align 32768      pre 1.56ms      on 1.89ms       post 1.68ms     diff 269µs
align 16384      pre 1.58ms      on 1.89ms       post 1.69ms     diff 261µs
align 8192       pre 1.38ms      on 1.91ms       post 1.81ms     diff 314µs
align 4096       pre 1.57ms      on 1.58ms       post 1.55ms     diff 23.8µs
align 2048       pre 1.65ms      on 1.65ms       post 1.61ms     diff 23.4µs

The most interesting parts of this result is that the diff changes drastically at two points:

- from 4194304 (4MB) to 2097152 (2MB). Based on the example readme in flashbench, this indicates that there was no performance overhead reading two blocks over the 2MB boundary, but there was for 4MB boundary. The guess then, is that the erasure block is 4MB large on the sd-card.

- At 8192 (8kB).

We can determine two things from this.

- Ext4 should have a block size of 4k, and the “stride” value should be 2. This will cause ext4 to think that units of 2 blocks (8k) can and should be treated as one.

- Ext4 should have the stripe-size set to 256. This value was calculated by taking 2M (guessed erasure block size) dividing by 8K (size of a stride, 2 times block size (4K)). This should cause ext4 to try to align writes so that erasure blocks are written continuously and make it avoid sub-block updates.

1. BLOCK_ERASURE = 4194304 il piu grande valore per il quale il tempo diventa vicino al doppio di quello precedente
2. BLOCK_SIZE(PAGE_SIZE) = 4096 il piu' piccolo valore per il quale il tempo diventa significamente superiore al precedente
3. ALIGN_PARTITION = $BLOCK_ERASURE/512 = 8192
4. prima part 64M 65536 block
5. seconda part 1G=1024*1000/$ALIGN_PARTITION=125 parte intera
6. 2_BLOCK_SIZE=125*$ALIGN_PARTITION -1

Device         Boot     Start       End  Blocks  Id System
/dev/mmcblk0p1           8192       73727  65535  83 Linux
/dev/mmcblk0p2          73728 7268351 2097152  83 Linux

Format with ext4 fs

EXT4_STRIPSIZE=$BLOCK_ERASURE/$BLOCK_SIZE=4194304 / 4096 = 1024

1. fdisk -lu disk
2. start block delle partizioni deve essere divisibile per BLOCK_ALIGN

mkfs.ext4 -O ^has_journal -E stride=2,stripe-width=$EXT4_STRIPSIZE -b 4096   /dev/mmcblk0p1

UUID=<some_long_uuid_number> / ext4 errors=remount-ro,noatime,nodiratime 0 1 elevator=noop

Benchmark

Optimze partition

Big file

sync; rm -f bigfile; sync; time ( dd if=/dev/zero of=bigfile bs=16k count=10000; sync) ;

10000+0 records in
10000+0 records out
163840000 bytes (164 MB) copied, 5.22952 s, 31.3 MB/s

real    0m15.791s
user    0m0.010s
sys     0m0.680s

small files

sync; rm -rf smallfiles_*; sync; time ( for i in `seq 1 100`; do dd if=/dev/zero of=smallfiles_$i bs=16k count=10; sync; done; ) ; rm -rf smallfiles_*

10+0 records in
10+0 records out
163840 bytes (164 kB) copied, 0.00119938 s, 137 MB/s

real    0m12.759s
user    0m0.040s
sys     0m0.120s

normal part

Big file

10000+0 records in
10000+0 records out
163840000 bytes (164 MB) copied, 13.2991 s, 12.3 MB/s
real    0m18.182s
user    0m0.030s
sys     0m0.760s

small files

10+0 records out
163840 bytes (164 kB) copied, 0.00121955 s, 134 MB/s

real    0m25.218s
user    0m0.060s
sys     0m0.100s