Theodore Tso wrote:
quoted text
> On Thu, May 14, 2009 at 08:21:05PM -0500, Eric Sandeen wrote:
>> it should lay out a 4g file in random 1m direct IOs to fragment it and
>> get a lot of extents, then launch 2 threads, one each doing random reads
>> and random writes of that same file.
>>
>> I can't make this trip it, though ...
> 
> If all of the blocks are in the page cache, you won't end up calling
> ext4_get_blocks().  Try adding a shell script which runs in parallel
> doing a "while /bin/true ; do sleep 1; echo 3 > /proc/sys/vm/drop_cache; done".
> 
> 							- Ted

I made sure it was a big enough file, and consumed enough memory on the
system before the test, that the entire file couldn't fit in memory.

I can try doing the dropping in the bg ... but it should have been going
to disk already.

-Eric
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