Re: O_NONBLOCK with Ext3

From: Yedire, Sandeep
Date: Sat Jun 12 2010 - 03:07:27 EST

On 12 June 2010 00:26, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote:
> "Yedire, Sandeep" <syedire@xxxxxxxxx> writes:
>> Hi ALL,
>> I am currently using o_nonblock flag for writing a file of 64MB over a
>> flash device. Flash is formatted with ext3 filesystem with default
>> options.
>> When instrumented the driver code for collecting the erase/write count
>> at sector level. I noticed that o_nonblock has no effect on this
>> count. There is no difference in erase/write count with o_nonblock
>> flag or without this flag.
>> When selected Ext2 as filesystem I noticed a significant difference in
>> the erase/write count.
>> There were more updates with o_nonblock and test application was
>> faster. I could confirm this by checking the Dirty page limit in the
>> background. It was updating faster in case of Ext2 not incase of Ext3.
>> Can any one explain on o_nonblock flag in case of  Ext3 filesystem?
> The O_NONBLOCK flag should be ignored when opening files on a file
> system.  I'm not sure how to explain your observations.
> What exactly were you trying to accomplish?
> Cheers,
> Jeff
> What exactly were you trying to accomplish?
I am only trying to observe the difference with O_NONBLOCK flag in the
updates to filesystem blocks and data blocks in Ext2 and Ext3

It was observed that with O_NONBLOCK flag in Ext2 there were less
updates to Filesystem block at sector 0, and frequent updates to data
blocks. This is not the case with Ext3.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at