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.
Thanks and Regards, Ram -----Original Message----- From: Pranith Kumar Karampuri [mailto:pkara...@redhat.com] Sent: Monday, December 14, 2015 11:13 PM To: Ankireddypalle Reddy; Vijay Bellur; gluster-users@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:pkara...@redhat.com] > Sent: Thursday, December 10, 2015 10:57 PM > To: Ankireddypalle Reddy; Vijay Bellur; gluster-users@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@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@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:pkara...@redhat.com] >> Sent: Wednesday, December 09, 2015 1:39 AM >> To: Ankireddypalle Reddy; Vijay Bellur; gluster-users@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:vbel...@redhat.com] >>> Sent: Monday, December 07, 2015 6:13 PM >>> To: Ankireddypalle Reddy; gluster-users@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 >>> >>> >>> >>> >>> >>> ***************************Legal >>> Disclaimer*************************** >>> "This communication may contain confidential and privileged material >>> for the sole use of the intended recipient. Any unauthorized review, >>> use or distribution by others is strictly prohibited. If you have >>> received the message by mistake, please advise the sender by reply email >>> and delete the message. Thank you." >>> ******************************************************************** >>> * >>> * _______________________________________________ >>> Gluster-users mailing list >>> Gluster-users@gluster.org >>> http://www.gluster.org/mailman/listinfo/gluster-users >> >> >> ***************************Legal >> Disclaimer*************************** >> "This communication may contain confidential and privileged material >> for the sole use of the intended recipient. 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