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Subject: Re: printing pv slow down question

Author: Uri Blass

Date: 06:30:58 08/16/04

Go up one level in this thread


On August 15, 2004 at 18:46:04, Mathieu Pagé wrote:

>On August 15, 2004 at 15:24:36, Uri Blass wrote:
>
>>On August 15, 2004 at 15:16:17, Mathieu Pagé wrote:
>>
>>>On August 15, 2004 at 12:13:59, Uri Blass wrote:
>>>
>>>>On August 15, 2004 at 12:01:56, Andrew Platt wrote:
>>>>
>>>>>Do not underestimate the cost of writing to Windows terminals! Particularly if
>>>>>the output is unbuffered it can be quite intense. Try this: Open a file as a
>>>>>test and send the output to there (default buffering of fopen is fine). See if
>>>>>you see the same slowdown.
>>>>>
>>>>>Andy.
>>>>
>>>>It cannot be the cost of writing because the difference between times when there
>>>>is no additional writing is also significantly bigger.
>>>>
>>>>I do not understand what is unbuffered output.
>>>>
>>>>I use fflush(stdout) after every printf but I know that I need to use
>>>>fflush(stdout) after lines that I print (otherwise the program may work in text
>>>>mode but not under winboard)
>>>
>>>Hi Uri,
>>>
>>>You are right, in order to work in Winboard you need to do fflush() after each
>>>output if you want winboard to get it instantly. However there is some
>>>informations that you send to winboard that did not need to be send so rapidely
>>>(like PV informations). So I sugest you to try (i did not) to use fflush only
>>>after critical informations like returning move, pong, etc. But not after pv.
>>>I'm absolutely not sure if it will help, so you should test it.
>>>
>>>Mathieu P.
>>
>>If the problem is speed of fflush I could expect no slow down when there is no
>>additional fflush but it is not the case.
>>
>>I already found a way to do the code more clearer and faster by dividing the
>>file iterate.c to 2 files when one of them is for searching the root moves like
>>crafty.
>>
>>Movei still has not enough files relative to crafty and I probably should divide
>>the program to more files.
>>
>>Uri
>
>Are you telling that the overhaed you are experiencing is not due to writing to
>stdout, but due to youre pv retreiving function ?
>
>Mathieu Pagé

Yes

It is clearly not because of writing to stdout but because the compiler does not
like additional calls to my pv retreiving function(this function is called
rarely).

Uri



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