On 12/16/2015 01:51 AM, Ankireddypalle Reddy wrote:> Thanks for the explanation. Valgrind profiling shows multiple memcpy's
being invoked for each write through libgfapi. Is there a way to avoid these
memcpy's?. Also is there a limit on the number of glfs_t* instances that can
be allocated at a given point of time. I've encountered cases where if more
than 8 glfs_t* instances are being allocated then glfs_init fails.
Including maintainers of gfapi.
Pranith
>
>
> Thanks and Regards,
> Ram
>
> -----Original Message-----
> From: Pranith Kumar Karampuri [mailto:pkarampu at redhat.com]
> Sent: Monday, December 14, 2015 11:13 PM
> To: Ankireddypalle Reddy; Vijay Bellur; gluster-users at gluster.org
> Subject: Re: [Gluster-users] libgfapi access
>
>
>
> 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 at redhat.com]
>> Sent: Thursday, December 10, 2015 10:57 PM
>> To: Ankireddypalle Reddy; Vijay Bellur; gluster-users at gluster.org
>> Subject: Re: [Gluster-users] 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 at gluster.org
>>> Subject: RE: [Gluster-users] 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 at 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 at 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 at redhat.com]
>>> Sent: Wednesday, December 09, 2015 1:39 AM
>>> To: Ankireddypalle Reddy; Vijay Bellur; gluster-users at
gluster.org
>>> Subject: Re: [Gluster-users] 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 at redhat.com]
>>>> Sent: Monday, December 07, 2015 6:13 PM
>>>> To: Ankireddypalle Reddy; gluster-users at gluster.org
>>>> Subject: Re: [Gluster-users] 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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