If you aleady are doing this - then thanks. But here's a feature I'd like to see. Rsync often puts a lot of load on the system because of high disk access. I'd like to see rsync become "load aware" and to slow itself down under high load levels. Seems to me that it could be something fairly easy to add to have it check the load levels and back down so as not to slow down the system. My 2 centz ...
On Tue, Feb 17, 2004 at 03:16:32PM -0800, Marc Perkel wrote:> If you aleady are doing this - then thanks. But here's a feature I'd > like to see. > > Rsync often puts a lot of load on the system because of high disk > access. I'd like to see rsync become "load aware" and to slow itself > down under high load levels. Seems to me that it could be something > fairly easy to add to have it check the load levels and back down so as > not to slow down the system.This is what process and i/o schedulars are for. In most cases rsync is i/o bound. Either disk or network. That means it spends most of its time sleeping already. This becomes increasingly true as the performance gulf grows between CPU and that of memory, disk and network. Perhaps you have a suggestion for defining what constitutes high load and how to determine that on all the different platforms? Hint: load average is meaningless. -- ________________________________________________________________ J.W. Schultz Pegasystems Technologies email address: jw@pegasys.ws Remember Cernan and Schmitt
Marc Perkel wrote:> down under high load levels. Seems to me that it could be something > fairly easy to add to have it check the load levels and back down so as > not to slow down the system.As jw indicated, it isn't such a great idea to put that into rsync itself. Instead, use the OS-supplied facilities. Suggestions: - nice/renice your rsync processes - use your OS to apply resource constraints (ulimit, bsd resource limits, etc). cheers, martin
>| What happens is that the server is cooking along just fine serving about >| 2 million hits a day. Load level - according to top is running around >| 0.6 to 2.3 or so - and then rsync kicks in doing a backup between the >| drives and even though I'm running at nice +19 the load kicks up to >| around 50 and several services almost stop. That's why I'm asking for >| this feature. > >I think your problem is saturation of the disk bandwidth. The high load >is just the result of that. Instead of watching the system load, itHow about using the --bwlimit option to start with? Not quite a hands free solution I know, but it will avoid you hammering the disks to oblivion. -ed -- Edward Grace Photonics Group, Physics Department Blackett Laboratory Imperial College SW7 2BW t: 020 759 47721 e: ej.grace@imperial.ac.uk