Feature Request - Load Throttling

Marc Perkel marc at perkel.com
Wed Feb 18 02:47:19 GMT 2004

Actually - the problem is disk IO. And the disk IO is what makes the 
load levels go up. The load level is something that's readable can can 
be used to have rsync slow itself down. Nice doesn't do the trick. Nice 
helps - but even at nice +19 it still slows the system to a crawl when 
backing up from one drive to another.

So - if rsync could watch the load levels and pause every now and then 
to put a little space between disk access at high load levels it would 
make it a lot friendlier to the system. The reason nice doesn't work is 
that once the system call is made to access the disk - nice doesn't apply.

jw schultz wrote:

>On Tue, Feb 17, 2004 at 03:16:32PM -0800, Marc Perkel wrote:
>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.

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