kernel defconfig, CONFIG_MTD_NAND_VERIFY_WRITE

Gennady Kupava gb at bsdmn.com
Wed Jan 6 10:49:07 CET 2010


hi all,

I still don't beleive our device should be so slow as it is now. I'll
try to investigate performance impact of several kernel option. I
expect, changes will be introduced to defalt config for distributions.
Here is first one CONFIG_MTD_NAND_VERIFY_WRITE.

Now it is enabled.

I build kernel with and without this option, and did read and write
tests to /dev/mtd6 and /dev/mtdblock6. all tests done with dd
to/from /dev/zero bs=256k count=200. read is just for check.

most data in Mb/s.

              mtd6-rd, mtd6-wt, mtdblock6-rd, mtdblock6-wt

option on     5.2,     4.8,     2.6,          900kb/s

option off    5.2,     2.4,     2.6, 	      712kb/s

I think mtdblock speed is good for approximation of real performance
impact of this option.

Think this option should be removed from defconfig, as it causes major
write slowdown (up to 2x).

Gennady.





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