[U-Boot] [PATCH 1/2] mtd: vf610_nfc: remove caching of page in buffer

[Bill Pringlemeir <bpringlemeir@nbsps.com>]

On  2 Apr 2015, stefan at agner.ch wrote:

> To improve performance we remember the current page in the buffer
> and avoid reading it twice. This implicit page cache increases
> complexity while does not increase performance in real world cases.
> This patch removes that feature.
> ---
> As discussed in the other patchset...
> http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/215802

> ...I did some performance measurements:

> Time to "Starting kernel ..."
> - without bad block scan & with UBIFS fastmap: 2.02s
> - with bad block scan & with UBIFS fastmap: 3.99s
> - without bad block scan & without UBIFS fastmap: 4.42s
> - with bad block scan & without UBIFS fastmap: 6.38s

> Without page cache (with this patch applied):
> Time to "Starting kernel ..."
> - without bad block scan & with UBIFS fastmap: 2.02s
> - with bad block scan & with UBIFS fastmap: 4.01s
> - without bad block scan & without UBIFS fastmap: 4.41s
> - with bad block scan & without UBIFS fastmap: 6.39s

[snip]

I also measured 'write performance' with the mtd_speedtest (performing
similar patch to the Linux driver) and I see no difference.  I think a
write benchmark is more appropriate to test this functionality?  While
at least it seems that neither read nor write is affected by the
simplification.

Fwiw,
Bill Pringlemeir.