On 12/11/2015 08:58 PM, Ankireddypalle Reddy wrote:
Pranith,
Thanks for checking this. Though the time taken to run was 18 seconds if you look at the time consumed in user land as well as kernel land for executing the command then it is evident that fuse took almost half the time as libgfapi. Also from the collected profiles it is evident that the average latency for the write command is less for fuse than for libgfapi. Are there any recommendations for I/O through libgfapi for disperse volumes. Is there any way to avoid the extra memcpy's that are being made when performing I/O through libgfapi.
hi Ankireddy,
Oh this is not a problem. If we use fuse, the system call
'write' from ./GlusterFuseTest will go through fuse-kernel, fuse kernel
sends the write operation to glusterfs mount process which is a user
process. Time taken to complete that call from then on is computed
against the glusterfs mount process until it responds to the
fuse-kernel, not against the ./GlusterFuseTest process. If we use gfapi,
there is no system call over head, instead ./GlusterFuseTest process
directly makes calls with the bricks through gfapi library. So all the
time that the process spends communicating with the bricks and getting
the response is counted against ./GlusterFuseTest. That is the reason
you see more 'user' time.
So again, There are quite a few workloads where gfapi has proven to give
better response times than fuse mounts because we avoid the context
switch costs of ./GlusterFuseTest -> fuse-kernel -> glusterfs-mount ->
fuse-kernel (for response)-> ./GlusterFuseTest (for response to 'write')
Hope that helps. Sorry for the delay in response, was in too many
meetings yesterday.
Pranith
Thanks and Regards,
Ram
-----Original Message-----
From: Pranith Kumar Karampuri [mailto:pkarampu@xxxxxxxxxx]
Sent: Thursday, December 10, 2015 10:57 PM
To: Ankireddypalle Reddy; Vijay Bellur; gluster-users@xxxxxxxxxxx
Subject: Re: libgfapi access
On 12/10/2015 07:15 PM, Ankireddypalle Reddy wrote:
Hi,
Please let me know in case you need any more details. Even for only write operations fuse seems to outperform libgfapi. Is it because of disperse volumes?. Also I noticed a lot of data loss in case I use libgfapi asyn I/O for disperse volumes.
Fuse and gfapi seem to take same amount of time to complete the run, i.e. 18 seconds. Could you let me know what you mean by fuse outperforming gfapi?
Pranith
Thanks and Regards,
Ram
-----Original Message-----
From: Ankireddypalle Reddy
Sent: Wednesday, December 09, 2015 5:01 PM
To: 'Pranith Kumar Karampuri'; Vijay Bellur; gluster-users@xxxxxxxxxxx
Subject: RE: libgfapi access
Hi,
I upgraded my setup to gluster 3.7.3. I tested writes by performing writes through fuse and through libgfapi. Attached are the profiles generated from fuse and libgfapi. The test programs essentially writes 10000 blocks each of 128K.
[root@santest2 Base]# time ./GlusterFuseTest /ws/glus 131072 10000 Mount path: /ws/glus Block size: 131072 Num of blocks: 10000 Will perform write test on mount path : /ws/glus Succesfully created file /ws/glus/1449697583.glfs Successfully filled file /ws/glus/1449697583.glfs Write test succeeded Write test succeeded.
real 0m18.722s
user 0m3.913s
sys 0m1.126s
[root@santest2 Base]# time ./GlusterLibGFApiTest dispersevol santest2
24007 131072 10000 Host name: santest2
Volume: dispersevol
Port: 24007
Block size: 131072
Num of blocks: 10000
Will perform write test on volume: dispersevol Successfully filled file 1449697651.glfs Write test succeeded Write test succeeded.
real 0m18.630s
user 0m8.804s
sys 0m1.870s
Thanks and Regards,
Ram
-----Original Message-----
From: Pranith Kumar Karampuri [mailto:pkarampu@xxxxxxxxxx]
Sent: Wednesday, December 09, 2015 1:39 AM
To: Ankireddypalle Reddy; Vijay Bellur; gluster-users@xxxxxxxxxxx
Subject: Re: libgfapi access
On 12/08/2015 08:28 PM, Ankireddypalle Reddy wrote:
Vijay,
We are trying to write data backed up by Commvault simpana to glusterfs volume. The data being written is around 30 GB. Two kinds of write requests happen.
1) 1MB requests
2) Small write requests of size 128 bytes. In case of libgfapi access these are cached and a single 128KB write request is made where as in case of FUSE the 128 byte write request is handled to FUSE directly.
glusterfs 3.6.5 built on Aug 24 2015 10:02:43
Volume Name: dispersevol
Type: Disperse
Volume ID: c5d6ccf8-6fec-4912-ab2e-6a7701e4c4c0
Status: Started
Number of Bricks: 1 x (2 + 1) = 3
Transport-type: tcp
Bricks:
Brick1: ssdtest:/mnt/ssdfs1/brick3
Brick2: sanserver2:/data/brick3
Brick3: santest2:/home/brick3
Options Reconfigured:
performance.cache-size: 512MB
performance.write-behind-window-size: 8MB
performance.io-thread-count: 32
performance.flush-behind: on
hi,
Things look okay. May be we can find something using profile info.
Could you post the results of the following operations:
1) gluster volume profile <volname> start
2) Run the fuse workload
3) gluster volume profile <volname> info > /path/to/file-1/to/send/us
4) Run the libgfapi workload
5)gluster volume profile <volname> info > /path/to/file-2/to/send/us
Send both these files to us to check what are the extra fops if any that are sent over network which may be causing the delay.
I see that you are using disperse volume. If you are going to use disperse volume for production usecases, I suggest you use 3.7.x preferably 3.7.3. We fixed a bug in releases from 3.7.4 till 3.7.6 which will be released in 3.7.7.
Pranith
Thanks and Regards,
Ram
-----Original Message-----
From: Vijay Bellur [mailto:vbellur@xxxxxxxxxx]
Sent: Monday, December 07, 2015 6:13 PM
To: Ankireddypalle Reddy; gluster-users@xxxxxxxxxxx
Subject: Re: libgfapi access
On 12/07/2015 10:29 AM, Ankireddypalle Reddy wrote:
Hi,
I am trying to use libgfapi interface to access gluster
volume. What I noticed is that reads/writes to the gluster volume
through libgfapi interface are slower than FUSE. I was expecting
the contrary. Are there any recommendations/settings suggested to be
used while using libgfapi interface.
Can you please provide more details about your tests? Providing information like I/O block size, file size, throughput would be helpful.
Thanks,
Vijay
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