Hi, Apologies in advance if this email is inappropriate for this mailing list. If so please let me know of a more suitable one. I noticed a significant performance difference when comparing a Centos5 (kernel 2.6.18) or Ubuntu (2.6.27-11) with a RH8 (kernel 2.4). All use NFS v3. The RH8 nfsd is faster than the 2.6 one even though it runs in an older, lower spec machine. See test details below Centos 5 x86_64 kernel 2.6.18-92.1.22.el5 RH8 2.4.20-30.8.multi_lun.smp #1 SMP i386 GNU/Linux 1Gb connection between machines File sizes are 1GB. The read speed of these files in the local machine filesystem (server) is around 98MBs in the Centos5 machine and around 65MBs in the old RH8 machine. .- First of all I wanted to measure how the network alone performs while using NFS. So in the server side I run a "cat" command on the 1GB file to /dev/null. At this point the file system has the 1GB file cached in memory. In the client side a "cat" on the same file gives me a speed of about 113MBs. Which is consistent with the 1Gb network. There is no performance hit. So far so good. .- The second test is reading from disk an uncache (in server and client) file. In the server and client I made sure I flushed the 1GB file from the memory. Between Centos5 machines the performance was about 35MBs (64% drop from the 98MBs disk read). Between RH8 machines the performance was 55MBs (15% drop from the 65MBs) This second test was repeated for ext2, ext3, xfs with no significant differences. Please note that the %iowait more than doubles when reading the file from the NFS partition vs the file system partition in the 2.6 kernels .- I run a third test just to make sure the problem is somehow related to the nfs daemon. I mounted the nfs partition local to the nfs server so the network was out the equation. I got the same poor results, no difference. Any ideas are most welcome, Thanks, I. -- 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
