[EMAIL PROTECTED] wrote on Fri, 15 Feb 2008 14:25 -0600:
> On Feb 15, 2008, at 1:17 PM, Pete Wyckoff wrote:
>> My unscientific study of listing 1000 files gives this:
>>
>> threading disabled (default)
>>
>> ib28$ time ls -la /pvfs > /dev/null
>> 0.004 user 0.024 sys 0.538 real
>> ib28$ time ls -la /pvfs > /dev/null
>> 0.008 user 0.016 sys 0.530 real
>> ib28$ time ls -la /pvfs > /dev/null
>> 0.004 user 0.024 sys 0.529 real
>> ib28$ time ls -la /pvfs > /dev/null
>>
>> threading enabled
>>
>> ib28$ time ls -la /pvfs > /dev/null
>> 0.012 user 0.024 sys 0.548 real
>> ib28$ time ls -la /pvfs > /dev/null
>> 0.008 user 0.024 sys 0.543 real
>> ib28$ time ls -la /pvfs > /dev/null
>> 0.000 user 0.036 sys 0.549 real
>>
>> Pretty minor difference, and doesn't show the benefits of threading
>> for multiple concurrent operations.
>
> Just from your output, it doesn't look like the listing commands are
> concurrent. Are you backgrounding each of those?
They're not concurrent. I was just looking at the overhead of
locking. But somebody more clever could do some concurrent tests
and probably see advantages. I'm mostly a believer in the
threadedness of the kmod helper. The test above just shows that the
locking overhead for single-client latency isn't terribly scary,
maybe a few percent at most.
-- Pete
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