Re: tbench regression in 2.6.25-rc1

[Valdis . Kletnieks]

On Mon, 18 Feb 2008 16:12:38 +0800, "Zhang, Yanmin" said:

> I also think __refcnt is the key. I did a new testing by adding 2 unsigned long
> pading before lastuse, so the 3 members are moved to next cache line. The performance is
> recovered.
> 
> How about below patch? Almost all performance is recovered with the new patch.
> 
> Signed-off-by: Zhang Yanmin <yanmin.zhang@xxxxxxxxx>

Could you add a comment someplace that says "refcnt wants to be on a different
cache line from input/output/ops or performance tanks badly", to warn some
future kernel hacker who starts adding new fields to the structure?

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