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.

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

Format with ext4 fs
EXT4_STRIPSIZE=$BLOCK_ERASURE/$BLOCK_SIZE

mkfs.ext4 -O ^has_journal -E stride=2,stripe-width=$EXT4_STRIPSIZE -b 4096  /dev/mmcblk0p1
 * 1) fdisk -lu disk
 * 2) start block delle partizioni deve essere divisibile per BLOCK_ALIGN

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

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

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