On Fri, Oct 22, 2010 at 5:44 AM, Suresh Jayaraman <sjayaraman@xxxxxxx> wrote: > > (Cc linux-cifs@xxxxxxxxxxxxxxx) > > On 10/22/2010 05:05 AM, J.A. Magallón wrote: > > Problem: speed is _VERY_ different. > > R/W through the automount point (CIFS fs), is roughly 7-8 MB/s (ridiculous > > for gigabit speeds). > > R/W through Gnome/gvfs (kind of fuse) goes around 35 - 40 MB/s (400 Mbits/s), > > that look much better. > > What is the kernel version In which you are seeing the problem? I'm not > seeing this on 2.6.36-rc4. Do you have a wired interface as well? Are > you sure that both are using the same network path? > > > I have tried with different rsize/wsize in mount, but speed is the same > > (perhaps I did not get the right values...). > Read sizes for cifs are relatively small at 16K (unless you change the maximum buffer sizes at insmod time), and cifs write size is 56K. This relatively smaller read size and the serializing of relatively small reads in cifs_readpages can cause slower speeds than you might expect reading files over gigabit if only one process is using the network especially if long network latency (lots of dead time on the network leading to low network utilizations). cifs will perform relatively well compared to other options as the number of processes accessing the network increases, because a lot of work has gone into locking. dbench results will often show 50 simultaneous requests to each Samba server (50 is the traditional maximum number of simultaneous requests that smb/cifs servers support). For workloads other than sequential read workloads - cifs does relatively better as well. In the future with smb2 the maximum number of requests can vary, and the maximum read size is larger which helps, as does the parallelized smb2 write code which Pavel wrote over the summer for Google Summer of Code. -- Thanks, Steve -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
