That is normal and probably comes from the page cache, should be about the same for lustre, ldiskfs, ext4, xfs, etc. It goes down if you specify "-odirect", but which is obviously not optimal on Lustre clients.
Cheers, Bernd On Wednesday, October 20, 2010, Andreas Dilger wrote: > Is this client CPU or server CPU? If you are using Ethernet it will > definitely be CPU hungry and can easily saturate a single core. > > Cheers, Andreas > > On 2010-10-20, at 8:41, Michael Kluge <[email protected]> wrote: > > Hi list, > > > > is it normal, that a 'dd' or an 'IOR' pushing 10MB blocks to a lustre > > file system shows up with a 100% CPU load within 'top'? The reason why I > > am asking this is that I can write from one client to one OST with 500 > > MB/s. The CPU load will be at 100% in this case. If I stripe over two > > OSTs (which use different OSS servers and different RAID controllers) I > > will get 500 as well (seeing 2x250 MB/s on the OSTs). The CPU load will > > be at 100% again. > > > > A 'dd' on my desktop pushing 10M blocks to the local disk shows 7-10% > > CPU load. > > > > Are there ways to tune this behavior? Changing max_rpcs_in_flight and > > max_dirty_mb did not help. > > > > > > Regards, Michael > > _______________________________________________ > Lustre-discuss mailing list > [email protected] > http://lists.lustre.org/mailman/listinfo/lustre-discuss _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
