Re: [Gluster-devel] 答复: Re: Gluster AFR volume write performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev

[li . ping288]

LiPing10168633/user/zte_ltd 写于 2016/01/28 21:40:30:

> From: 李平10168633/user/zte_ltd
> To: Pranith Kumar Karampuri <pkara...@redhat.com>, 
gluster-devel@gluster.org, 
> Cc: li.y...@zte.com.cn, liu.jianj...@zte.com.cn, 
> yang.bi...@zte.com.cn, zhou.shigan...@zte.com.cn
> Date: 2016/01/28 21:40
> Subject: Re: 答复: Re: [Gluster-devel] Gluster AFR volume write 
> performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND
> in afr_writev
> 
> Sorry for the late reply.
> 
> Pranith Kumar Karampuri <pkara...@redhat.com> 写于 2016/01/25 17:48:06:
> 
> > From: Pranith Kumar Karampuri <pkara...@redhat.com>
> > To: li.ping...@zte.com.cn, 
> > Cc: li.y...@zte.com.cn, zhou.shigan...@zte.com.cn, 
> > liu.jianj...@zte.com.cn, yang.bi...@zte.com.cn
> > Date: 2016/01/25 17:48
> > Subject: Re: 答复: Re: [Gluster-devel] Gluster AFR volume write 
> > performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND
> > in afr_writev
> > 
> > 

> > On 01/25/2016 03:09 PM, li.ping...@zte.com.cn wrote:
> > Hi Pranith, 
> > 
> > I'd be willing to have a chance to do my contribution to open-source. 
> > It's my first time to deliver a patch for GlusterFS, hence I'm not 
> > quite familiar with the code review and submitting procedures. 
> > 
> > I'll try to make it ASAP. By the way is there any guidelines to dothis 
work?
> > http://www.gluster.org/community/documentation/index.php/
> > Simplified_dev_workflow may be helpful. Feel free to ask any doubt 
> > you may have.
> > 
> > How do you guys use glusterfs?
> > 
> > Pranith

> Thanks for your warm tips.  We currently use glusterfs to build the 
> shared storage for distributed cluster nodes.
> 
> Here are the solutions I pondered over these days:
> 
> 1，Reverting the AFR GLUSTERFS_WRITE_IS_APPEND modifications. 
> because this optimization only play a part for appending write fops, 
>  but most of the time of writing it is not kind of this. Hence I
> think it is not worth to do an optimization for the low probability 
> situation 
>  at cost of the vast majority of AFR writing performance drop. 
> 2，Revising the fixed GLUSTERFS_WRITE_IS_APPEND dictionary option in
> afr_writev in a dynamic way.  i.e. adding a new dynamic configurable
>  option "write_is_append" just as the existing "ensure-
> durability" for AFR.  It could be configured on if AFR writing 
> performance is not mainly 
>  concerned and off if the performance is demanded.
> 
> I have been trying to find out a way in posix_writev to predict the 
> appending write  in advance and then lock/unlock or not lock 
> accordingly in the 
> shortest and soonest, but I get no chance.

3,  Another compromising solution crossing my mind today is to let the 
WRITE_IS_APPEND not 
take effect for O_DIRECT option. It is already  ineffective for SYNC 
writing, and also the performance for 
page cache writing is not so bad (not as good as no locking of course).

I would prefer the 2th and 3th way.

Are there any other opinions?

> 
> Anybody's other good ideas are appreciated.
> 
> Ping.Li
> 
> > 
> > Thanks & Best Regards. 
> > 
> > Pranith Kumar Karampuri <pkara...@redhat.com> 写于 2016/01/23 
14:01:36:
> > 
> > > From: Pranith Kumar Karampuri <pkara...@redhat.com> 
> > > To: li.ping...@zte.com.cn, gluster-devel@gluster.org, 
> > > Cc: li.y...@zte.com.cn, liu.jianj...@zte.com.cn, 
> > > zhou.shigan...@zte.com.cn, yang.bi...@zte.com.cn 
> > > Date: 2016/01/23 14:02 
> > > Subject: Re: 答复: Re: [Gluster-devel] Gluster AFR volume write 
> > > performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND
> > > in afr_writev 
> > > 
> > > 
> > 
> > > On 01/22/2016 07:14 AM, li.ping...@zte.com.cn wrote: 
> > > Hi Pranith, it is appreciated for your reply. 
> > > 
> > > Pranith Kumar Karampuri <pkara...@redhat.com> 写于 2016/01/20 
18:51:19:
> > > 
> > > > 发件人:  Pranith Kumar Karampuri <pkara...@redhat.com> 
> > > > 收件人:  li.ping...@zte.com.cn, gluster-devel@gluster.org, 
> > > > 日期:  2016/01/20 18:51 
> > > > 主题: Re: [Gluster-devel] Gluster AFR volume write performance has 

> > > > been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev 

> > > > 
> > > > Sorry for the delay in response.
> > > 
> > > > On 01/15/2016 02:34 PM, li.ping...@zte.com.cn wrote: 
> > > > GLUSTERFS_WRITE_IS_APPEND Setting in afr_writev function at 
> > > > glusterfs client end makes the po

Re: [Gluster-devel] 答复: Re: Gluster AFR volume write performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev

[li . ping288]

Sorry for the late reply.

Pranith Kumar Karampuri <pkara...@redhat.com> 写于 2016/01/25 17:48:06:

> From: Pranith Kumar Karampuri <pkara...@redhat.com>
> To: li.ping...@zte.com.cn, 
> Cc: li.y...@zte.com.cn, zhou.shigan...@zte.com.cn, 
> liu.jianj...@zte.com.cn, yang.bi...@zte.com.cn
> Date: 2016/01/25 17:48
> Subject: Re: 答复: Re: [Gluster-devel] Gluster AFR volume write 
> performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND
> in afr_writev
> 
> 

> On 01/25/2016 03:09 PM, li.ping...@zte.com.cn wrote:
> Hi Pranith, 
> 
> I'd be willing to have a chance to do my contribution to open-source. 
> It's my first time to deliver a patch for GlusterFS, hence I'm not 
> quite familiar with the code review and submitting procedures. 
> 
> I'll try to make it ASAP. By the way is there any guidelines to do this 
work?
> http://www.gluster.org/community/documentation/index.php/
> Simplified_dev_workflow may be helpful. Feel free to ask any doubt 
> you may have.
> 
> How do you guys use glusterfs?
> 
> Pranith

Thanks for your warm tips.  We currently use glusterfs to build the shared 
storage for distributed cluster nodes.

Here are the solutions I pondered over these days:

1，Reverting the AFR GLUSTERFS_WRITE_IS_APPEND modifications.  because 
this optimization only play a part for appending write fops, 
 but most of the time of writing it is not kind of this. Hence I think 
it is not worth to do an optimization for the low probability situation 
 at cost of the vast majority of AFR writing performance drop. 
2，Revising the fixed GLUSTERFS_WRITE_IS_APPEND dictionary option in 
afr_writev in a dynamic way.  i.e. adding a new dynamic configurable
 option "write_is_append" just as the existing "ensure-durability" for 
AFR.  It could be configured on if AFR writing performance is not mainly 
 concerned and off if the performance is demanded.
 
I have been trying to find out a way in posix_writev to predict the 
appending write  in advance and then lock/unlock or not lock accordingly 
in the 
shortest and soonest, but I get no chance.

Anybody's other good ideas are appreciated.

Ping.Li

> 
> Thanks & Best Regards. 
> 
> Pranith Kumar Karampuri <pkara...@redhat.com> 写于 2016/01/23 14:01:36:
> 
> > From: Pranith Kumar Karampuri <pkara...@redhat.com> 
> > To: li.ping...@zte.com.cn, gluster-devel@gluster.org, 
> > Cc: li.y...@zte.com.cn, liu.jianj...@zte.com.cn, 
> > zhou.shigan...@zte.com.cn, yang.bi...@zte.com.cn 
> > Date: 2016/01/23 14:02 
> > Subject: Re: 答复: Re: [Gluster-devel] Gluster AFR volume write 
> > performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND
> > in afr_writev 
> > 
> > 
> 
> > On 01/22/2016 07:14 AM, li.ping...@zte.com.cn wrote: 
> > Hi Pranith, it is appreciated for your reply. 
> > 
> > Pranith Kumar Karampuri <pkara...@redhat.com> 写于 2016/01/20 
18:51:19:
> > 
> > > 发件人:  Pranith Kumar Karampuri <pkara...@redhat.com> 
> > > 收件人:  li.ping...@zte.com.cn, gluster-devel@gluster.org, 
> > > 日期:  2016/01/20 18:51 
> > > 主题: Re: [Gluster-devel] Gluster AFR volume write performance has 
> > > been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev 
> > > 
> > > Sorry for the delay in response.
> > 
> > > On 01/15/2016 02:34 PM, li.ping...@zte.com.cn wrote: 
> > > GLUSTERFS_WRITE_IS_APPEND Setting in afr_writev function at 
> > > glusterfs client end makes the posix_writev in the server end  deal 
> > > IO write fops from parallel  to serial in consequence. 
> > > 
> > > i.e.  multiple io-worker threads carrying out IO write fops are 
> > > blocked in posix_writev to execute final write fop pwrite/pwritev in
> > > __posix_writev function ONE AFTER ANOTHER. 
> > > 
> > > For example: 
> > > 
> > > thread1: iot_worker -> ...  -> posix_writev()   | 
> > > thread2: iot_worker -> ...  -> posix_writev()   | 
> > > thread3: iot_worker -> ...  -> posix_writev()   -> __posix_writev() 
> > > thread4: iot_worker -> ...  -> posix_writev()   | 
> > > 
> > > there are 4 iot_worker thread doing the 128KB IO write fops as 
> > > above, but only one can execute __posix_writev function and the 
> > > others have to wait. 
> > > 
> > > however, if the afr volume is configured on with storage.linux-aio 
> > > which is off in default,  the iot_worker will use posix_aio_writev 
> > > instead of posix_writev to write data. 
> > > the posix_aio_writev function won't be affected by 
> > > GLUSTERFS_WRITE_IS_APPE

Re: [Gluster-devel] 答复: Re: Gluster AFR volume write performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev

[Pranith Kumar Karampuri]

On 01/22/2016 07:14 AM, li.ping...@zte.com.cn wrote:

Hi Pranith, it is appreciated for your reply.

Pranith Kumar Karampuri  写于 2016/01/20 18:51:19:

> 发件人:  Pranith Kumar Karampuri 
> 收件人:  li.ping...@zte.com.cn, gluster-devel@gluster.org,
> 日期:  2016/01/20 18:51
> 主题: Re: [Gluster-devel] Gluster AFR volume write performance has
> been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev
>
> Sorry for the delay in response.

> On 01/15/2016 02:34 PM, li.ping...@zte.com.cn wrote:
> GLUSTERFS_WRITE_IS_APPEND Setting in afr_writev function at
> glusterfs client end makes the posix_writev in the server end  deal
> IO write fops from parallel  to serial in consequence.
>
> i.e.  multiple io-worker threads carrying out IO write fops are
> blocked in posix_writev to execute final write fop pwrite/pwritev in
> __posix_writev function ONE AFTER ANOTHER.
>
> For example:
>
> thread1: iot_worker -> ...  -> posix_writev()   |
> thread2: iot_worker -> ...  -> posix_writev()   |
> thread3: iot_worker -> ...  -> posix_writev() -> __posix_writev()
> thread4: iot_worker -> ...  -> posix_writev()   |
>
> there are 4 iot_worker thread doing the 128KB IO write fops as
> above, but only one can execute __posix_writev function and the
> others have to wait.
>
> however, if the afr volume is configured on with storage.linux-aio
> which is off in default,  the iot_worker will use posix_aio_writev
> instead of posix_writev to write data.
> the posix_aio_writev function won't be affected by
> GLUSTERFS_WRITE_IS_APPEND, and the AFR volume write performance goes 
up.

> I think this is a bug :-(.

Yeah, I agree with you. I suppose the GLUSTERFS_WRITE_IS_APPEND is a 
misuse in afr_writev.
I checked the original intent of GLUSTERS_WRITE_IS_APPEND change at 
review website:

_http://review.gluster.org/#/c/5501/_

The initial purpose seems to avoid an unnecessary fsync()in
afr_changelog_post_op_safe function if the writing data position
was currently at the end of the file, detected by
(preop.ia_size == offset || (fd->flags & O_APPEND)) in posix_writev.

In comparison with the afr write performance loss, I think
it costs too much.

I suggest to make the GLUSTERS_WRITE_IS_APPEND setting configurable
just as ensure-durability in afr.


You are right, it doesn't make sense to put this option in dictionary if 
ensure-durability is off. http://review.gluster.org/13285 addresses 
this. Do you want to try this out?
Thanks for doing most of the work :-). Do let me know if you want to 
raise a bug for this. Or I can take that up if you don't have time.


Pranith


>
> So, my question is whether  AFR volume could work fine with
> storage.linux-aio configuration which bypass the
> GLUSTERFS_WRITE_IS_APPEND setting in afr_writev,
> and why glusterfs keeps posix_aio_writev different from posix_writev ?
>
> Any replies to clear my confusion would be grateful, and thanks in 
advance.

> What is the workload you have? multiple writers on same file workloads?

I test the afr gluster volume by fio like this:
fio --filename=/mnt/afr/20G.dat --direct=1 --rw=write --bs=128k 
--size=20G --numjobs=8
--runtime=60 --group_reporting --name=afr_test  --iodepth=1 
--ioengine=libaio


The Glusterfs BRICKS are two IBM X3550 M3.

The local disk direct write performance of 128KB IO req block size is 
about 18MB/s

in single thread and 80MB/s in 8 multi-threads.

If the GLUSTERS_WRITE_IS_APPEND is configed, the afr gluster volume 
write performance is 18MB/s
as the single thread, and if not, the performance is nearby 
75MB/s.(network bandwith is enough)


>
> Pranith
>
>
> 
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>
>

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[Gluster-devel] 答复: Re: Gluster AFR volume write performance has been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev

[li . ping288]

Hi Pranith, it is appreciated for your reply.

Pranith Kumar Karampuri  写于 2016/01/20 18:51:19:

> 发件人:  Pranith Kumar Karampuri 
> 收件人:  li.ping...@zte.com.cn, gluster-devel@gluster.org, 
> 日期:  2016/01/20 18:51
> 主题: Re: [Gluster-devel] Gluster AFR volume write performance has 
> been seriously affected by GLUSTERFS_WRITE_IS_APPEND in afr_writev
> 
> Sorry for the delay in response.

> On 01/15/2016 02:34 PM, li.ping...@zte.com.cn wrote:
> GLUSTERFS_WRITE_IS_APPEND Setting in afr_writev function at 
> glusterfs client end makes the posix_writev in the server end  deal 
> IO write fops from parallel  to serial in consequence. 
> 
> i.e.  multiple io-worker threads carrying out IO write fops are 
> blocked in posix_writev to execute final write fop pwrite/pwritev in
> __posix_writev function ONE AFTER ANOTHER. 
> 
> For example: 
> 
> thread1: iot_worker -> ...  -> posix_writev()   | 
> thread2: iot_worker -> ...  -> posix_writev()   | 
> thread3: iot_worker -> ...  -> posix_writev()   -> __posix_writev() 
> thread4: iot_worker -> ...  -> posix_writev()   | 
> 
> there are 4 iot_worker thread doing the 128KB IO write fops as 
> above, but only one can execute __posix_writev function and the 
> others have to wait. 
> 
> however, if the afr volume is configured on with storage.linux-aio 
> which is off in default,  the iot_worker will use posix_aio_writev 
> instead of posix_writev to write data. 
> the posix_aio_writev function won't be affected by 
> GLUSTERFS_WRITE_IS_APPEND, and the AFR volume write performance goes up. 

> I think this is a bug :-(.

Yeah, I agree with you. I suppose the GLUSTERFS_WRITE_IS_APPEND is a 
misuse in afr_writev.
I checked the original intent of GLUSTERS_WRITE_IS_APPEND change at review 
website:
http://review.gluster.org/#/c/5501/ 

The initial purpose seems to avoid an unnecessary fsync() in 
afr_changelog_post_op_safe function if the writing data position 
was currently at the end of the file, detected by 
(preop.ia_size == offset || (fd->flags & O_APPEND)) in posix_writev.

In comparison with the afr write performance loss, I think 
it costs too much. 

I suggest to make the GLUSTERS_WRITE_IS_APPEND setting configurable
just as ensure-durability in afr.

> 
> So, my question is whether  AFR volume could work fine with 
> storage.linux-aio configuration which bypass the 
> GLUSTERFS_WRITE_IS_APPEND setting in afr_writev, 
> and why glusterfs keeps posix_aio_writev different from posix_writev ? 
> 
> Any replies to clear my confusion would be grateful, and thanks in 
advance.
> What is the workload you have? multiple writers on same file workloads?

I test the afr gluster volume by fio like this:
fio --filename=/mnt/afr/20G.dat --direct=1 --rw=write --bs=128k --size=20G 
--numjobs=8 
--runtime=60 --group_reporting --name=afr_test  --iodepth=1 
--ioengine=libaio

The Glusterfs BRICKS are two IBM X3550 M3. 

The local disk direct write performance of 128KB IO req block size is 
about 18MB/s 
in single thread and 80MB/s in 8 multi-threads.

If the GLUSTERS_WRITE_IS_APPEND is configed, the afr gluster volume write 
performance is 18MB/s
as the single thread, and if not, the performance is nearby 
75MB/s.(network bandwith is enough)

> 
> Pranith
> 
> 
> 
> ZTE Information Security Notice: The information contained in this 
> mail (and any attachment transmitted herewith) is privileged and 
> confidential and is intended for the exclusive use of the addressee
> (s).  If you are not an intended recipient, any disclosure, 
> reproduction, distribution or other dissemination or use of the 
> information contained is strictly prohibited.  If you have received 
> this mail in error, please delete it and notify us immediately.
> 

> 
> 

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