Mbed-os: LittleFS fopen() is really slow on QSPI flash

[janjongboom]

Description

fopen() when used with LittleFS is ~15 times slower than with FATFileSystem when using it on the QSPI flash on the DISCO-L475VG-IOT01A board. My test script:

        Timer t;
        t.start();
        FILE *write_file = fopen("/fs/weights/y_pred_some_file.idx", "w+");
        t.stop();
        printf("fopen took %d ms.\n", t.read_ms());

This takes between 129 and 151 ms. on my board with LittleFS, but only 10-11 ms. with FATFileSystem.

@geky

Issue request type

[X] Question
[ ] Enhancement
[X] Bug

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOCUSTRIA-1497

[geky]

This is more likely due to directory structure layout than QSPI specifically. I'm guessing it's related to https://github.com/ARMmbed/littlefs/issues/75. Unfortunately all I can say right now is that I am planning on looking at it but it will take time.

[janjongboom]

@geky Thanks for pointing me to that issue.

[0xc0170]

Shall this be closed ? As it's being tracked in littlefs repo issue 75

[0xc0170]

If anyone follows this one, please follow ARMmbed/littlefs#75.

I'll close this as there is an issue related in the upstream repository.