[Ocfs2-devel] RFC: OCFS2 heartbeat improvements

[Sunil Mushran]

Yes. WRITE_SYNC should be good. Not FUA.

Also, you may want to look into using io priorities. The code is all there.
Just needs activation.

On Wed, Aug 22, 2012 at 10:13 AM, srinivas eeda <srinivas.eeda at oracle.com>wrote:

>
> On 8/22/2012 7:17 AM, Jie Liu wrote:
>
> Hi All,
>
> These days, I am investigating an issue regarding OCFS2 unexpected reboot
> in some real world use cases.
> This problem occurred when the network status goes south, when the disk IO
> load is too high, etc...
> I suspect it might caused by ocfs2 fencing if it's BIO reading/writing can
> not be scheduled and processed quickly, or
> something like this happened in the network IO heartbeat thread.
>
> Now am trying to reproduce this problem locally.  In the meantime, I'd
> like to ping you guys with some rough ideas
> to improve the disk IO heartbeat to see if they are sounds reasonable or
> not.
>
> Firstly, if an OCFS2 node is suffer from heavy disk IO, how about to fix
> the bio read/write to make this IO request can not
> be preempted by other requests? e.g,  for o2hb_issue_node_write(),
> currently, it do bio submission with WRITE only,
> 'submit_bio(WRITE, bio)'.   If we change the flag to WRITE_SYNC, or even
> submit the request combine with REQ_FUA,
> maybe could get highest priority for disk IO request.
>
> This was submitted before by Noboru Iwamatsu and acked by sunil and tao
> but some how didn't get merged
>
> https://oss.oracle.com/pipermail/ocfs2-devel/2011-December/008438.html
>
>
> Secondly, the comments for bio allocation at o2hb_setup_one_bio()
> indicates that we can pre-allocate bio instead of
> acquire for each time.  But I have not saw any code snippet doing such
> things in kernel. :(
> how about creating a private bio set for each o2hb_region, so that we can
> do allocation out of it?
> maybe it's faster than do allocation from global bio sets.  Also, does it
> make sense if creating a memory pool
> on each o2hb_region, so that we can have continuous pages bind to those
> bios?
>
>
> Any comments are appreciated!
>
> Thanks,
> -Jeff
>
>
>
>
>
>
>
>
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