[RFC] consistent_sync and non L1 cache line aligned buffers

[Eugene Surovegin]

At 01:18 PM 7/15/2003, Darin.Johnson at nokia.com wrote:

>I solved the problem (in a non-Linux system) by just flushing the first
>and last lines in the requested range, and invalidating the rest.  The
>very slight performance hit is probably less than testing to see if the
>buffer is unaligned.

I don't think so.

If you take a look at the assembler output of my patch you'll see that test
for unaligned just accesses register, when dcbf may require memory access
which is *significantly* slower.

In majority of cases consistent_sync is called with properly aligned buffer
and I don't want to penalize this path by *unconditionally* (as you are
suggesting) flushing start and end of the buffer.

Eugene.


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