On Mon, Mar 12, 2018 at 02:39:35PM +0100, Sergio Traldi wrote: > thanks for answering, I understand your response, but the problem is > not exactly the disk writing or disk synchronization. I'm quite sure it is. Try something like strace -T tar zxvf root_v6.08.06.Linux-centos7-x86_64-gcc4.8.tar.gz And look at the times for the openat()s and close()s. In the local case they'll probably be in the 10s of microseconds. In the NFS case they'll probably be in the 10s of milliseconds (assuming a conventional spinning hard drive). That's because and NFS open and close requires waiting for the server to commit changes to disk (waiting for possibly multiple disk seeks), while the local filesystem does not have to do that. --b. > > I tried to do a simple test just in one host so the network has been > keep out. (Just the network interface could be taken into account.) > > I have a bare metal host: > > With this simple features: > > O.S: > CentOS Linux release 7.4.1708 (Core) > > Kernel: > Linux cld-ctrl-pa-02.cloud.pd.infn.it 3.10.0-693.2.2.el7.x86_64 #1 > SMP Tue Sep 12 22:26:13 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux > > disk: > Disk /dev/sda: 500.1 GB, 500107862016 bytes, 976773168 sectors > Units = sectors of 1 * 512 = 512 bytes > Sector size (logical/physical): 512 bytes / 512 bytes > I/O size (minimum/optimal): 512 bytes / 512 bytes > Disk label type: dos > Disk identifier: 0x000709ef > > Device Boot Start End Blocks Id System > /dev/sda1 * 2048 2099199 1048576 83 Linux > /dev/sda2 2099200 18876415 8388608 82 Linux swap / Solaris > /dev/sda3 18876416 976773119 478948352 83 Linux > > controller disk: > IDE interface: Intel Corporation 82801JI (ICH10 Family) 4 port SATA > IDE Controller #1 > > I have this rpms for nfs and rpc: > [ ~]# rpm -qa | grep nfs > libnfsidmap-0.25-17.el7.x86_64 > nfs-utils-1.3.0-0.48.el7_4.1.x86_64 > > [ ~]# rpm -qa | grep rpc > libtirpc-0.2.4-0.10.el7.x86_64 > rpcbind-0.2.0-42.el7.x86_64 > > I try in direcory /nfstest to untar my file I obtain: > [ ~]# time tar zxvf root_v6.08.06.Linux-centos7-x86_64-gcc4.8.tar.gz > .... > real 0m7.324s > user 0m7.018s > sys 0m2.474s > > In this case you should say there be a cache in memory of kernel and > command tar, so I try to use the option -w for tar the help say: > -w, --interactive, --confirmation > ask for confirmation for every action > > So I think I force the tar command to do each file a file open and a > file close I use this command: > > [ ~]# time yes y | tar xzvfw > root_v6.08.06.Linux-centos7-x86_64-gcc4.8.tar.gz > .... > sreal 0m7.590s > user 0m7.247s > sys 0m2.569s > > I conclude the time to write thoose files in disk is about 8 seconds. > > Now in same host (192.168.60.171) I mount /nfstest in same host in > /nfsmount: > [ ~]# cat /etc/exports > /nfstest 192.168.60.0/24(rw,sync,no_wdelay,no_root_squash,no_subtree_check) > > mount -t nfs 192.168.60.171:/nfstest/ /nfsmount/ > > I can see with mount command: > [ ~]# mount > ... > 192.168.60.171:/nfstest on /nfsmount type nfs4 (rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.60.171,local_lock=none,addr=192.168.60.171) > > and I try to untar my file: > [ ~]# time tar zxvf root_v6.08.06.Linux-centos7-x86_64-gcc4.8.tar.gz > .... > real 11m27.853s > user 0m8.466s > sys 0m5.435s > > So I can not understand why the untar take about 8 seconds and the > untar using directory mounted with nfs in same host take about 11 > minutes and 30 seconds, in all the 2 case there be a fo and fc. > I know there are a file open and file close and ACK in the case of > NFS so I expect an overhead, but not a so big overhead. I think > there be something other wrong in the protocol or some timeout > somewhere. > > I agree with you if I use big file the problem is reduced: > In host: > time tar zxvf test.tgz > Fedora-Server-netinst-x86_64-27-1.6.iso > Fedora-Workstation-Live-x86_64-27-1.6.iso > > real 0m52.047s > user 0m24.382s > sys 0m11.597s > > > Mounted via NFS: > time tar zxvf test.tgz > Fedora-Server-netinst-x86_64-27-1.6.iso > Fedora-Workstation-Live-x86_64-27-1.6.iso > > real 0m55.453s > user 0m25.905s > sys 0m10.095s > > There is a way to got nfs server from source and build may be with > some verbose logging or build with some optimization to this > "performance problem". > > Cheers > Sergio > > On 03/05/2018 10:50 PM, J. Bruce Fields wrote: > >This should be on a FAQ or something. Anyway, because I've been > >thinking about it lately: > > > >On an NFS filesystem, creation of a new file is a synchronous operation: > >the client doesn't return from open()/creat() until it's gotten a > >response from the server, and the server isn't allowed to respond until > >it knows that the file creation has actually reached disk--so it'll > >generally be waiting for at least a disk seek or two. > > > >Also when it finishes writing a file and closes it, the close() has to > >wait again for the new data to hit disk. > > > >That's probably what dominates the runtime in your case. Take the > >number of files in that tarball and divide into the total runtime, and > >the answer will probably be about the time it takes to create one file > >and commit the write data on close. > > > >As you know, exporting with async is not recommended--it tells the > >server to violate the protocol and lie to the client, telling it that > >the client that stuff has reached disk when it hasn't really. This > >works fine until you have a power outage and a bunch of files that the > >file has every right to believe were actually sync'd to disk suddenly > >vanish.... > > > >Other possible solutions/workarounds: > > > > - use storage that can commit data to stable storage very > > quickly: this is what most "real" NFS servers do, generally I > > think by including some kind of battery-backed RAM to use as > > write cache. I don't know if this is something your HP > > controllers should be able to do. > > > > The cheapo version of this approach that I use for my home > > server is an SSD with capacitors sufficient to destage the > > write cache on shutdown. SSDs marketed as "enterprise" often > > do this--look for something like "power loss protection" in > > the specs. Since I was too cheap to put all my data on SSDs, > > I use an ext4 filesystem on a couple big conventional drives, > > mounted with "data=journal" and an external journal on an SSD. > > > > - write a parallel version of tar. Tar would go a lot faster if > > it wasn't forced to wait for one file creation before starting > > the next one. > > > > - implement NFS write delegations: we've got this on the client, > > I'm working on the server. It can't help with the latency of > > the original file create, but it should free the client from > > waiting for the close. But I don't know if/how much it will > > help in practice yet. > > > > - specify/implement NFS directory write delegations: there's not > > really any reason the client *couldn't* create files locally > > and later commit them to the server, somebody just needs to > > write the RFC's and the code. > > > > I seem to remember Trond also had a simpler proposal just to > > allow the server to return from a file-creating OPEN without > > waiting for disk if it returned a write delegation, but I > > can't find that proposal right now.... > > > >--b. > > > >On Mon, Mar 05, 2018 at 10:53:21AM +0100, Sergio Traldi wrote: > >>I have host A and host B using nfs4 or nfs3. > >>In host A I mount a partition or a disk formatted in ext4 or xfs in > >>/nfsdisk > >>I put this file inside the directory: > >>wget --no-check-certificate https://root.cern.ch/download/root_v6.08.06.Linux-centos7-x86_64-gcc4.8.tar.gz > >>-O /nfsdisk/root_v6.08.06.Linux-centos7-x86_64-gcc4.8.tar.gz > >> > >>In host A I export that partition with this line in /etc/exports > >>/nfsdisk > >>192.168.1.1.0/24(rw,sync,no_wdelay,no_root_squash,no_subtree_check) > >>OR using async mode: > >>/nfsdisk 192.168.1.1.0/24(rw,async,no_root_squash) > >> > >> From host B I mount via nfs the disk: > >>mount -t nfs <ip-hostA>:/nfsdisk /nfsdisk > >> > >>and I obtain something similar to (with mount command): > >>192.168.1.1:/nfstest on /nfstest type nfs4 (rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.1.2,local_lock=none,addr=192.168.1.1) > >> > >>In host B I exec: > >>time tar zxvf root_v6.08.06.Linux-centos7-x86_64-gcc4.8.tar.gz > >> > >>I try with different hosts bare metal or virtual machine and with > >>different controller. > >>1) with bare metal host: > >>1.1) A and B bare metal with CentOS7 with kernel 3.10.0-514.2.2.el7 > >>with nfs-utils-1.3.0-0.48.el7_4.1.x86_64 and > >>rpcbind-0.2.0-42.el7.x86_64 > >> > >>In host A: > >>real 0m45.338s > >>user 0m8.334s > >>sys 0m5.387s > >> > >>In Host B I obtain > >> sync mode: > >>real 11m56.146s > >>user 0m9.947s > >>sys 0m8.346s > >> async mode: > >>real 0m46.328s > >>user 0m8.709s > >>sys 0m5.747s > >> > >>1.2) A and B bare metal with Ubuntu 14.04 jessie with kernel > >>3.13.0-141-generic with nfs-common 1:1.2.8-6ubuntu1.2 - nfs-server > >>1:1.2.8-6ubuntu1.2 - rpcbind 0.2.1-2ubuntu2.2 > >> > >>In host A: > >>real 0m10.667s > >>user 0m7.856s > >>sys 0m3.190s > >> > >>In host B: > >> sync mode: > >>real 9m45.146s > >>user 0m9.697s > >>sys 0m8.037s > >> async mode: > >>real 0m14.843s > >>user 0m7.916s > >>sys 0m3.780s > >> > >>1.3) A and B bare metal with Scientific Linux 6.2 with Kernel > >>2.6.32-220.el6.x86_64 with nfs-utils-1.2.3-15.el6.x86_64 - > >>rpcbind-0.2.0-13.el6_9.1.x86_64 > >> > >>In host A: > >>real 0m5.943s > >>user 0m5.611s > >>sys 0m1.585s > >> > >>In host B: > >> sync mode: > >>real 8m37.495s > >>user 0m5.680s > >>sys 0m3.091s > >> async mode: > >>real 0m21.121s > >>user 0m5.782s > >>sys 0m3.089s > >> > >>2) with Virtual Machine Libvirt KVM > >>2.1) A and B virtual with CentOS7 with kernel 3.10.0-514.2.2.el7 > >>with nfs-utils-1.3.0-0.48.el7_4.1.x86_64 and > >>rpcbind-0.2.0-42.el7.x86_64 > >> > >>In host A: > >>real 0m46.126s > >>user 0m9.034s > >>sys 0m6.187s > >> > >>In Host B I obtain > >> sync mode: > >>real 12m31.167s > >>user 0m9.997s > >>sys 0m8.466s > >> async mode: > >>real 0m45.388s > >>user 0m8.416s > >>sys 0m5.587s > >> > >>2.2) A and B virtual with Ubuntu 14.04 jessie with kernel > >>3.13.0-141-generic with nfs-common 1:1.2.8-6ubuntu1.2 - nfs-server > >>1:1.2.8-6ubuntu1.2 - rpcbind 0.2.1-2ubuntu2.2 > >>In host A: > >>real 0m10.787s > >>user 0m7.912s > >>sys 0m3.335s > >> > >>In Host B I obtain > >> sync mode: > >>real 11m54.265s > >>user 0m8.264s > >>sys 0m6.541s > >> async mode: > >>real 0m11.457s > >>user 0m7.619s > >>sys 0m3.531s > >> > >>Just in two other bare metal hosts I have same situation of 1.3 (old > >>O.S. and old nfs) and I obtain sync and asyc mode in host B similar > >>in about: > >>real 0m37.050s > >>user 0m9.326s > >>sys 0m4.220s > >>in that case the host A has a controller RAID bus controller: > >>Hewlett-Packard Company Smart Array G6 controllers (rev 01) > >> > >>Now my question why is there to much difference from sync and async mode? > >> > >>I try to optimize network in A and B, I try to mount with different > >>rsize and wsize in B host, I try to change timeo in nfs from B.| > >>I try to to increase nfsd threads in host A. > >>I try to change disk scheduler ( /sys/block/sda/queue/scheduler noop > >>deadline [cfq]) in host A. > >>I try to use NFS3. > >> > >>I observe some little improvement in some case but the gap from > >>async and sync is always very high, except for the bare metal with > >>G6 array controller. > >> > >>We would like to use nfs with sync for our infrastructure, but we > >>can not loose to much performance. > >> > >>Is there a way to use sync mode with some specific parameter and > >>improve considerably performance? > >> > >>Thanks in advance for any hint. > >>Cheers > >>Sergio > >> > >>-- > >>To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > >>the body of a message to majordomo@xxxxxxxxxxxxxxx > >>More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
