On Mon, February 7, 2011 14:49, Yi Zhang wrote:
> On Mon, Feb 7, 2011 at 3:14 PM, Bill Sommerfeld <sommerf...@alum.mit.edu>
> wrote:
>> On 02/07/11 11:49, Yi Zhang wrote:
>>>
>>> The reason why I
>>> tried that is to get the side effect of no buffering, which is my
>>> ultimate goal.
>>
>> ultimate = "final".  you must have a goal beyond the elimination of
>> buffering in the filesystem.
>>
>> if the writes are made durable by zfs when you need them to be durable,
>> why
>> does it matter that it may buffer data while it is doing so?
>>
>>                                                -
>> Bill
>
> If buffering is on, the running time of my app doesn't reflect the
> actual I/O cost. My goal is to accurately measure the time of I/O.
> With buffering on, ZFS would batch up a bunch of writes and change
> both the original I/O activity and the time.

I'm not sure I understand what you're trying to measure (which seems to be
your top priority).  Achievable performance with ZFS would be better using
suitable caching; normally that's the benchmark statistic people would
care about.

-- 
David Dyer-Bennet, d...@dd-b.net; http://dd-b.net/
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