Found nn messages in the processing-messages database
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Mon Apr 20 15:02:40 IST 2009
On 20/04/2009 13:40, Glenn Steen wrote:
> 2009/4/20 Kai Schaetzl<maillists at conactive.com>:
>> Anyway, the point is, that many of us will simply don't need this. It's just
>> some more milliseconds added to processing. In the recent past people have
>> already complained several times about performance. Why hamper performance
>> where it is not necessary?
> I think Jules is aiming at microseconds...:-). And as such, well spent;)
> Who knows, perhaps one should do it as an option ... Like: if you use
> the processing DB, then you get deterministic "entropy" added to the
> queue file name, else you get the regular entropy as we have had for
> quite some time now.
I don't intend adding a configuration option for something as small as
this. The overall effect on speed will be tiny, it just has to read 256
bytes out of a file that it will be about to read into memory anyway, so
the cost does not involve a single disk read, it will be in memory
buffers anyway. I would be interested to see if you can actually make
the load difference measurable on a real system.
I deliberately and carefully chose a checksum algorithm that would work
as fast as possible while providing the necessary resilience that it's
there for. It is far faster than a CRC check, let alone something crazy
like MD5. If you read the code, you can work out the number of add and
mask operations that are used in its implementation. It doesn't involve
a single multiply or divide operation, just bit-masking and adding.
And furthermore, 99.99% of users would never change the option as they
wouldn't understand it, and I try to avoid having tweaks that only 1
user will ever change. And don't forget that it costs time to evaluate a
configuration option, they aren't free.
You have the source. If you don't like it, supply your own PostfixKey
subroutine in Postfix.pm.
>> Btw, Julian, you wanted me to remind you that the processing db option should
>> be set to off by default! :-)
Thank you for the reminder.
In the next stable release I do intend to make it off by default, I
fully intended to leave it on in the betas so it would be tested.
Julian Field MEng CITP CEng
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