[stgt] [PATCH 1/1] tgtd: Patch to add bsoflags options o tgtd.

[Daniel Henrique Debonzi]

FUJITA Tomonori wrote:
> On Tue, 18 May 2010 16:21:00 -0300
> Daniel Henrique Debonzi <debonzi at linux.vnet.ibm.com> wrote:
> 
>> One idea to solve it and don't make necessary to touch all backing 
>> stores to avoid this issue is to create a new template like bs_rdrw_sync 
>> O_SYNC and O_DIRECT flags on open, and don't have the options as this 
>> patch does. This way I got want I am interested in and don't need to 
>> involve all the other stuff. What are your thoughts about it?
> 
> Or a new option to touch only bs_rdrw.
> 
> However, I want to know why you want to use O_SYNC and O_DIRECT.
> 
> - what's the advantage of O_SYNC compared with the current approach
> (sync_file after write)? notably faster?

We would like to be able to control those flags because for our case it 
has better performance. Some tests done recently showed that we can get 
good better results when using O_DIRECT than sync_file.

> - why do you want to use O_DIRECT with bd_rdrw? bd_aio does aio with
>   O_DIRECT? It's not enough for you?

AIO does not work with the kernel version we are using at moment.

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