linux-kernel - Antw: Re: MBR partitions slow?

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Message-Id: <57C7E738020000A1000226A1@gwsmtp1.uni-regensburg.de>
Date:   Thu, 01 Sep 2016 08:30:48 +0200
From:   "Ulrich Windl" <Ulrich.Windl@...uni-regensburg.de>
To:     <mrustad@...il.com>
Cc:     <linux-kernel@...r.kernel.org>
Subject: Antw: Re: MBR partitions slow?

>>> Mark D Rustad <mrustad@...il.com> schrieb am 31.08.2016 um 17:32 in Nachricht
<E2D72371-913B-4460-A370-C141835AD919@...il.com>:
> Ulrich Windl <Ulrich.Windl@...uni-regensburg.de> wrote:
> 
>> So without partition the throughput is about twice as high! Why?
> 
> My first thought is that by starting at block 0 the accesses were aligned  
> with the flash block size of the device. By starting at a partition, the  
> accesses probably were not so aligned.

Hi!

Thanks for answering. Yes, you are right: Usually I use fdisk to create partitions, and the tool does proper aligning for the partitions. In my case YaST insisted on having a partition before creating a filesystem, so I created on within YaST, and that partition turned out to be badly aligned (I think Yast uses cfdisk internally). I'm sorry that I didn't think about that earlier!

Stracing fdisk, I also learned about ioctl(BLKIOOPT) and related...

Regards,
Ulrich

> 
> --
> Mark Rustad, MRustad@...il.com