On Thu, Mar 22, 2012 at 05:49:44PM +0100, Emmanuel Florac wrote: > Hi list, > I have this problem of (relatively) poor samba read performance. Read > performance is constantly, reproducibly lower than write performance > and I can't really understand why. > > Here is the server configuration : > > dual octocore Opteron 6128, 32 GB RAM > Adaptec 6445 RAID card > 36x 2TB Hitachi SATA drives (raid 60) > > Sustained local disk throughput: over 850 MB/s write, over 1.4 GB/s > read. > > kernel 3.1.10 (but I tried various versions with no more > success), amd64, pure vanilla kernel.org version. > Distro Debian squeeze amd64, samba 2:3.5.6~dfsg-3squeeze5 > > The client is an opteron dual core machine running Win7 64 bits. This is > by far the best performing CIFS client I've tested, software wise (see > below). > > The systems are connected in 10GigE ethernet using Myricom Myri-10G > dual ports (only one port used) through a Fujitsu 10GigE switch. > > I first tested the same client to the same server using Linux (same > configuration as the server) and netperf, then NFS, then cifs mount. > > Netperf (TCP_SENDFILE test) gives more than 9500 Mb/s both direction, so > the network hardware works OK. > > NFS gives the following results both in UDP and TCP modes: > Sustained throughput: 490 to 520 MB/s write, 620 to 650 MB/s read. > > The linux CIFS client running on the same machine writes at a puny 180 > MB/s and read at a miserable 75 MB/s. OK, never mind, samba is for > windows clients, right? > > Now, the same machine rebooted under windows 7 writes at 450 MB/s, > which is close enough to NFS performance, but can't top 400 MB/s > reading. Read performance *should* be higher. I've played with various > parameters; I can get better write performance at times, on par with > NFS, but I never at any time remotely get as good a read performance. > > I'd really like to get this beast tamed at last :) > > > Here comes the smb.conf file : > > [global] > name resolve order = wins lmhosts host bcast > socket options = TCP_NODELAY > > interfaces = eth2 > bind interfaces only = yes > aio read size = 1 > aio write size = 1 > aio write behind = yes
Until the next 3.6.x ships with the aio_pthread module, you might we better off removing the "aio XXX" lines. Linux glibc aio is fundamentally broken (and Ulrich doesn't seem interested in fixing it) - this is why I ended up writing the aio_pthread module. You could try using Volker's aio_fork module, which might help (with the Linux clients, but probably not the Windows clients unless you're running SMB2). You're you're more adventurous you could try running from v3-6-test git tree and ensure you have the aio_pthread module loaded. Jeremy. -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
