Re: [PATCH] Optimize pattern verify

[Jens Axboe <jaxboe@fusionio.com>]

On 02/07/2012 03:50 AM, Steven Lang wrote:
> Similar to the patch last week, this optimizes the pattern verify
> operation to use optimized library calls like memcmp(), and only fall
> back to byte-by-byte if there is a miscompare to locate it.
> 
> This uses the same premise that the pattern is repeated as many times
> as possible to do large compares in a single call.  For single byte
> pattern, the setup fills the pattern space, and verify assumes it is
> full.
> 
> Tested by running a script which created an 8k file with 4k bs and,
> one byte at a time, tried corrupting the pattern and running a read
> pass and verified it still found miscompares across the whole range of
> the pattern.  This was done with a pattern length of 1 and 3 bytes.
> 
> In performance tests, this was about 8 times more efficient on
> verifies than without this patch.

Great, applied! Thanks.

-- 
Jens Axboe