[Verizon] Slow read/write speeds, any suggestions?

wayrad · Feb 25, 2013

I purchased my GNex used, so I don't know its history. I rooted it, ran stock for a while, and have tried CM10, Sourcery 3.1, and (currently) Sourcery 4.5. Ever since I first benchmarked it (prior to rooting), I've noticed that Quadrant gives a very low I/O score. Here are the readings (those in parentheses are what Quadrant says a GNex should be):

Quadrant:

Total - 2036 (2574)
CPU - 5609 (5661)
Mem - 1668 (1804)
I/O - 1096 (3533)
2D - 163 (346)
3D - 1780 (1526)

I also tried Androbench, which is showing unusually slow sequential read/write speeds and random write speeds:

Androbench:

#Micro-benchmark
SEQ RD - 21.57 MB/s
SEQ RW - 3.36 MB/s
RND RD - 1769.3 IOPS (4K)
RND WR - 40.58 IOPS (4K)

#SQLite benchmark
Insert 27.69 TPS
Update 28.99 TPS
Delete 31.84 TPS

#Macro benchmark
Target:/data (ext 4)
Browser:214 msec
Market: 705 msec

I've seen similar problems reported elsewhere, and people have speculated that it has to do with filling up the storage (which the previous owner may have done for all I know, but I have 15 GB left). The only cures I've seen suggested are a factory reset or formatting data, both of which I've tried unsuccessfully. Rooting seemed to help a smidgen, but not much. Reflashing after a full wipe doesn't help.

Any suggestions? Did I buy a lemon?

iwoloschin · Feb 25, 2013

Did you try running "TRIM" commands? I'm not sure it'd actually help, but it shouldn't hurt. Try "LagFix Free" in the Play Store.

Otherwise, try wiping everything. Like, the entire internal memory. Once it's totally wiped, you should be able to reinstall via Recovery (using adb push to get a zip file on the phone). Again, not sure it would actually help, but in theory, it would reset your phone to "like new" IO conditions.

wayrad · Feb 25, 2013

iwoloschin said:
Did you try running "TRIM" commands? I'm not sure it'd actually help, but it shouldn't hurt. Try "LagFix Free" in the Play Store.

Otherwise, try wiping everything. Like, the entire internal memory. Once it's totally wiped, you should be able to reinstall via Recovery (using adb push to get a zip file on the phone). Again, not sure it would actually help, but in theory, it would reset your phone to "like new" IO conditions.

Thanks for the quick reply and the suggestions! LagFix Free didn't seem to do much of anything. I guess I'll have to try wiping internal memory (eeeeekk!) once I make sure I know what I'm doing with adb. I don't have a lot of experience with it other than during rooting.

quickaudi · Feb 25, 2013

What is your read ahead speed set to?

wayrad · Feb 26, 2013

quickaudi said:
What is your read ahead speed set to?

Dunno, where would I find that? It's not something I've ever messed with.

Edited to add: In Sourcery Tools' Kernel Settings, I found some "I/O Control" data:

Scheduler: row
Read Ahead Buffer Size: 1024

Is that what you mean?

quickaudi · Feb 26, 2013

wayrad said:
Dunno, where would I find that? It's not something I've ever messed with.

Edited to add: In Sourcery Tools' Kernel Settings, I found some "I/O Control" data:

Scheduler: row
Read Ahead Buffer Size: 1024

Is that what you mean?

Yup. Try bumping that up, like double.

wayrad · Feb 27, 2013

quickaudi said:
Yup. Try bumping that up, like double.

That bumped Quadrant I/O speed to 1375 (still very low). Androbench sequential read is 25.97, sequential write 1.43, random read 1854.25, random write 49.34 - no improvement really, looks like random variation.

I notice Androbench also has a way to set sequential and random buffer sizes (defaults are 256 KB and 4KB respectively). Does that mean it's ignoring the kernel settings?

wayrad · Mar 3, 2013

I'm trying to make sure I know what I'm doing before I wipe the internal memory, and have what may be a dumb question (I know I don't really understand the way memory is partitioned). Anyway, I wiped the sd card when I unlocked the bootloader, right? And that gave only a slight improvement in read/write speeds. And I do a full wipe every time I flash, and that gives no improvement at all. So, why would it help to do everything all at once? What am I missing?

wayrad · Apr 26, 2013

Well, this is...bizarre. But nice.

I never did find time to fiddle with ADB and wipe my SD card, but when I flashed the latest Sourcery earlier in the week, instead of doing the usual full wipe I flashed Superwipe instead. Suddenly Quadrant is telling me that my I/O is up to usual GNex speeds.

The weird thing is, I used Superwipe once before without success. The only difference is that I was using Clockworkmod Recovery then, and now I'm on TWRP. Very weird indeed, but I'm not complaining.

[Verizon] Slow read/write speeds, any suggestions?

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