All - I cant remember if its been suggested, but will a stack-trace to see what block sizes are being sent on each kernel version be helpful in this situation ?
Next I would look for : (1) netpipe tests to see if this is network driver/etc related (2) changelog between the two kernels Kyle Schochenmaier On Mon, Dec 14, 2009 at 4:10 PM, claude pignol <[email protected]> wrote: > Phil Carns wrote: >> >> claude pignol wrote: >>> >>> Greetings, >>> >>> Thanks for your previous answers on the compatibility 2.7.1/ 2.8.1 >>> >>> I have a strange problem: >>> Version 2.7.1 >>> I/O server AMD Opteron 2350 kernel 2.6.18-164.el5 >>> Client AMD Opteron 2350 kernel 2.6.18-164.el5 >>> In this configuration cp a file from pvfs (using the kernel interface) is >>> running at 40MB/s >>> >>> If the client is an Intel Xeon 5550 and the kernel 2.6.18-164.el5 the cp >>> is running at 9 MB/s >>> and it could go as low as 1.9MB/s with block size of 32KB (dd if=testfile >>> of=/dev/null bs=32K count=2000) >>> >>> I did a test with an older kernel 2.6.18-128.el5 on the Intel Xeon 5550 >>> an I get a transfer speed of 40MB/s even with 32K block. >>> So something has changed in the 164 version. I tested also the version >>> 2.6.18-164.6.1 and get the same low speed. >>> >>> Is this a known problem? >>> Claude >> >> Hi Claude, >> >> What kind of network card does the machine have? Have you tried any >> network benchmarks (netpipe or similar) to see if there is network >> performance is different in general between the two versions? >> >> -Phil >> >> > Hi Phil, > > The network chip on the motherboard is an Intel Corporation 82576 Gigabit > Network Connection > and It works OK. The problem is the same on all the nodes of a cluster. > Something has changed in the 2.6.18-164.el5 kernel compare to .6.18-128.el5 > > client machine Intel Xeon 5550 with 2.6.18-164.el5 > Read from pvfs (interface kernel using dd) > block 32K 1.6MB/s block 64K 18.0 MB/s > block 128K 62.5 MB/s > > > The same machine with 2.6.128.el5 > Read from pvfs (interface kernel using dd) > block 32K 41MB/s > block 64K 62.1MB/s > block 128K 61MB/s > > > Claude > > -- > This email was Anti Virus checked by Astaro Security Gateway. > http://www.astaro.com > _______________________________________________ > Pvfs2-users mailing list > [email protected] > http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users > _______________________________________________ Pvfs2-users mailing list [email protected] http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
