Re: [PATCH 0/3] mtd: block2mtd: convert to folios

[Tal Zussman]

On 10/15/26 2:39 PM, Jörn Engel wrote:
> On Wed, Oct 14, 2026 at 11:34:53PM -0400, Tal Zussman wrote:
>> 
>> The numbers below are from mtd_speedtest, in MiB/s, by folio size,
>> except the last row, which is from the MEMERASE ioctl:
>> 
>> +------------------------------+-------+--------+---------+---------+
>> | Test                         | Folio |   Base | Patched |  Change |
>> +------------------------------+-------+--------+---------+---------+
>> | Eraseblock read (128 KiB)    |   4K  |  12545 |   12863 |   +2.5% |
>> |                              |  16K  |  12998 |   17229 |  +32.6% |
>> |                              |  64K  |  13009 |   19135 |  +47.1% |
>> +------------------------------+-------+--------+---------+---------+
> 
> Thank you!  Code size goes down, code seems subjectively easier to read
> and performance goes up.  Good stuff!
> 
> The one pet complaint I have is that benchmarks should measure badness,
> not goodness.  Humans tend to prioritize the big numbers.  If you
> measure the bad thing (time in this case), they focus on the worst areas
> where most time is spent.  If you measure the good thing, they tend to
> improve things that are already too good to worry about even further.
> 
> Maybe you are immune to such psychological effects, but I am not and
> measuring time instead of throughput makes a difference to my mind.
Understandable :) I just used the output of mtd_speedtest, which
doesn't directly report time at the moment, but with some tweaks...
Results are the time in ms that mtd_speedtest takes for one pass over
a 256 MiB device.

+------------------------------+-------+--------+---------+---------+
| Test                         | Folio |   Base | Patched |  Change |
+------------------------------+-------+--------+---------+---------+
| Eraseblock read (128 KiB)    |   4K  |  20.25 |   19.55 |   -3.4% |
|                              |  16K  |  20.19 |   14.55 |  -27.9% |
|                              |  64K  |  20.21 |   13.24 |  -34.5% |
+------------------------------+-------+--------+---------+---------+
| Eraseblock write (128 KiB)   |   4K  |  26.37 |   25.01 |   -5.1% |
|                              |  16K  |  26.10 |   17.62 |  -32.5% |
|                              |  64K  |  25.69 |   15.45 |  -39.8% |
+------------------------------+-------+--------+---------+---------+
| Page read (512 B)            |   4K  |  75.70 |   72.02 |   -4.9% |
|                              |  16K  |  76.50 |   73.00 |   -4.6% |
|                              |  64K  |  76.44 |   72.96 |   -4.5% |
+------------------------------+-------+--------+---------+---------+
| Page write (512 B)           |   4K  | 113.57 |  109.59 |   -3.5% |
|                              |  16K  | 114.42 |  109.73 |   -4.1% |
|                              |  64K  | 114.39 |  109.57 |   -4.2% |
+------------------------------+-------+--------+---------+---------+
| 2-page read (1 KiB)          |   4K  |  48.42 |   46.40 |   -4.2% |
|                              |  16K  |  48.96 |   47.07 |   -3.9% |
|                              |  64K  |  48.59 |   47.07 |   -3.1% |
+------------------------------+-------+--------+---------+---------+
| 2-page write (1 KiB)         |   4K  |  63.61 |   61.28 |   -3.7% |
|                              |  16K  |  63.96 |   61.20 |   -4.3% |
|                              |  64K  |  63.82 |   60.85 |   -4.6% |
+------------------------------+-------+--------+---------+---------+
| Erase, blocks hold data      |   4K  |  15.40 |   14.13 |   -8.3% |
| (mtd_speedtest)              |  16K  |  15.28 |   10.48 |  -31.4% |
|                              |  64K  |  15.22 |   10.13 |  -33.4% |
+------------------------------+-------+--------+---------+---------+
| Erase, already erased        |   4K  |  23.86 |   15.11 |  -36.7% |
| (2x multi-block)             |  16K  |  24.14 |   11.46 |  -52.5% |
|                              |  64K  |  23.63 |   10.53 |  -55.5% |
+------------------------------+-------+--------+---------+---------+

Thanks,
Tal