| Re: time cost for file reading increasing!!! same file! [message #69733 is a reply to message #69721] |
Tue, 09 February 2010 10:22   |
minchen
Messages: 8
Registered: February 2010
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Junior Member |
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I think this is not the reason. Since the speed is slow down with
time. At later time, it may cost 10 minutes to read a file. At fist is
less than 0.1s.
On Feb 8, 6:04 pm, wlandsman <wlands...@gmail.com> wrote:
> On second thought, the OP is only reading, not writing, to disk, so
> the memory cache may not be relevant.
>
> On Feb 8, 9:00 pm, wlandsman <wlands...@gmail.com> wrote:
>
>
>
>> On Feb 8, 6:20 pm, minchen <mchen...@gmail.com> wrote:
>
>>> Hi everyone,
>>> I meet a mysterious problem on IDL file reading.
>>> The problem is as following:
>>> I just read the same hdf5 file seveal times and see the time costing.
>>> I find the first 270 file reading is very quickly but after that, the
>>> reading speed drops down although the file is the same one.
>
>> I am reaching here, but maybe the problem is similar to one discussed
>> in an earlier thread (http://tinyurl.com/yzrvd96) where the correct
>> question should be "Why is the file reading so fast to start
>> with?" Those fast times are deceptive because the IDL thinks the I/
>> O operation is complete after it has passed the data to the memory
>> cache, but the OS has not yet written the data to disk. Once the
>> memory cache fills, then IDL has to wait until the data is written to
>> the mechanical disk, but those longer times are a better measure of
>> the time to write the data to disk.
>
>> --Wayne- Hide quoted text -
>
> - Show quoted text -
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