| Re: time cost for file reading increasing!!! same file! [message #69721] |
Wed, 10 February 2010 06:00  |
Juggernaut
Messages: 83
Registered: June 2008
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Member |
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On Feb 9, 1:22 pm, minchen <mchen...@gmail.com> wrote:
> 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 -
Which version of IDL are you using?
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