Re: ubi/ubifs performance comparison on two NAND devices

[Richard Weinberger <richard@xxxxxx>]

Am Freitag, 1. März 2019, 17:41:06 CET schrieb Tim Harvey:
> Steve,
> 
> I've compared erase/read/write speeds for both flashes and the Cypress
> flash is 2x slower than the Micron on a 'per-byte-size' basis (which
> is what I would expect as the datasheets have pretty much the same
> timings per 'block' but the micron has 2x larger blocks and the chips
> are the same overall size meaning the cypress would have 2x as many
> 'block' operations across the same size).
> 
> So, at a raw erase/read/write level the Cypress is 2x slower than
> Micron, but ubi-scan is 7x slower (4s to 28s), and ubifs-space-fixup
> is 100x slower (0.5s to 50s).
> 
> I guess i've made a mess of the description of the issue. I can dig in
> and find the basic flash timings the kernel is using 'but' when I test
> using flash_erase and dd for erase/read/write over say 60M I find the
> expected 2x slower performance. I just don't understand why I see a
> much slower performance at the ubi and ubifs layers.

Can we please start with decent numbers?
Is UBI really slower than expected? Or only UBIFS file read/write?

I'm still totally confused by your allegations.

Thanks,
//richard



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