On 18.10.2017 13:31, Thomas Singer wrote: > Hi, > > When performing following steps on my old Linux test machine (with > slow hard disk): > > - have a SVN working copy at /home/user/test > - sudo apt install nfs-kernel-server > - add following line to /etc/exports: > /home/user/test *(rw,sync,no_root_squash) > - start the NFS server: > sudo systemctl start nfs-kernel-server.service > - mount the NFS share: > sudo mount localhost:/home/user/test /home/user/test.nfs > > and then open /home/user/test.nfs in SmartSVN 9.2 (using SVN 1.9 > JavaHL binaries), adding/removing a file is very slow. It boils down > to the call ISVNClient.getChangelists which takes ~8s on the NFS share > (/home/user/test.nfs). First, I thought, it would be caused by the > native-Java overhead calling the call-back ~11,000 times for my > working copy, but when using the working copy directly > (/home/user/test), the method just takes <1s though the ~11,000 times > call-back invocations are still there. > > My working copy has no local modifications, no untracked or ignored > files, no changelists. > > Is it expected that this method (ISVNClient.getChangelists) is so slow > on a NFS share even if there are no changelists?
I don't know if it's "expected" but I bet that NFS is killing SQLite performance. https://www.mail-archive.com/sqlite-users@mailinglists.sqlite.org/msg88989.html I'm not sure about the reason but the most likely answer, apart from slow data rate and latency when compared to a local filesystem (which, in your case on loopback, should not be an issue), is that the OS can't really use a cache for files on NFS since it has no way to know whether or not it's valid. With a lot of random-access reads and writes, that can be a HUGE slowdown, as you found. Also this: https://sqlite.org/faq.html#q5 In other words, Subversion working copies on NFS are, and have always been, a bad idea; not only because of SQLite but also because Subversion's code itself relies on atomic renames, which NFS does not provide. -- Brane
