Re: O_NONBLOCK with Ext2/3

From: Yedire, Sandeep
Date: Fri Jun 11 2010 - 00:34:54 EST

On 11 June 2010 06:20, Robert Hancock <hancockrwd@xxxxxxxxx> wrote:
> On 06/10/2010 06:44 AM, Yedire, Sandeep wrote:
>> Hi All,
>> What is the effect  on filesystem blocks,data blocks if O_NONBLOCK
>> flag is used with a test application doing write to a file(64MB) on
>> NAND Flash.
>> Can any one please let me know
>> Regards,
>> Sandeep.Yedire
> O_NONBLOCK doesn't do anything on regular files, as far as I'm aware. It's
> only useful on sockets, serial ports/TTYs, etc.

[Sandeep] In Ext2 fs, I have noticed many frequent updates to data
blocks as compared to without this flag. I also noticed Dirty page
limit (44MB max) with O_NONBLOCK and 18 to 20MB max without this
flag. Because of this there is less Filesystem block updates with

In case of Ext3, Dirty page limit is 18-20MB with or without this flag.
Its same with all modes of Ext3(data, ordered, writeback).

This is actually my concern.

Many Thanks,
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