Message-ID: <3EE7D7F5.3070803@cyberone.com.au>
Date: Thu, 12 Jun 2003 11:31:33 +1000
From: Nick Piggin <piggin@cyberone.com.au>
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To: Andrew Morton <akpm@digeo.com>
CC: Robert Love <rml@tech9.net>, bos@serpentine.com,
       linux-kernel@vger.kernel.org
Subject: Re: [patch] as-iosched divide by zero fix
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Andrew Morton wrote:

>Robert Love <rml@tech9.net> wrote:
>
>>Fix as-iosched divide-by-zero bug.
>>
>
>hrm, OK.  Still not convinced about `batch'.
>
>How about this?
>

Yeah, thats the way to do it, of course. It was too
jumpy at that setting though, so make it batch*3
(or <<1+batch if you don't want the multiply).

>
>--- 25/drivers/block/as-iosched.c~as-div-by-zero-fix	2003-06-11 18:17:04.000000000 -0700
>+++ 25-akpm/drivers/block/as-iosched.c	2003-06-11 18:20:58.000000000 -0700
>@@ -930,13 +930,12 @@ void update_write_batch(struct as_data *
> 		write_time = 0;
> 
> 	if (write_time > batch + 5 && !ad->write_batch_idled) {
>-		if (write_time / batch > 2)
>+		if (write_time > batch * 2)
> 			ad->write_batch_count /= 2;
> 		else
> 			ad->write_batch_count--;
>-		
> 	} else if (write_time + 5 < batch && ad->current_write_count == 0) {
>-		if (batch / write_time > 2)
>+		if (batch > write_time * 2)
> 			ad->write_batch_count *= 2;
> 		else
> 			ad->write_batch_count++;
>
>_
>
>
>  
>

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