[Python-Dev] __file__

[Brett Cannon]

On Sun, Feb 28, 2010 at 16:31, Greg Ewing <greg.ewing at canterbury.ac.nz>wrote:

> Robert Collins wrote:
>
>> In the special
>> case of probing for $name.$ext1, ...$ext2, ...$ext3, you generally hit
>> the same pages and don't incur additional page in costs.
>>
>
> So then looking for a .pyc alongside a .py or vice versa
> should be almost free, and we shouldn't be worrying about
> it.
>

But that is making the assumption that all filesystems operate this way
(.e.g does NFS have the same performance characteristics?).


>
>  hot cache:
>> % time     seconds  usecs/call     calls    errors syscall
>> ------ ----------- ----------- --------- --------- ----------------
>>  45.10    0.000368          92         4           getdents
>>  0.00    0.000000           0       734       625 stat
>>
>
> Further supporting the idea that stat calls are negligible
> once the cache is warmed up.


But that's the point: once it's warmed up. This is not the case when
executing a script once every once in a while compared to something bzr
where you are most likely going to execute the command multiple times within
a small timeframe.

-Brett




>
>
> --
> Greg
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