Feature Request - Load Throttling
marc at perkel.com
Wed Feb 18 03:34:06 GMT 2004
jw schultz wrote:
>On Tue, Feb 17, 2004 at 06:47:19PM -0800, Marc Perkel wrote:
>>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.
>Is that is on AIX with 12 AS400 CPUs or the VMS SSI cluster?
>Or is that a single CPU linux box with a 2.4.?? kernel?
It's on a dual xeon with 4 gigs of ram and a pair of 250 gig serial ata
>>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.
>What load levels? Do you have some nice C code that can do
>that for ALL the platforms without misreading?
>This is what process and i/o schedulers are for.
>Maybe you should contact the people responsible for whatever
>kernel it is you are running.
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
I'd rather get a response from real develpers than nay sayers telling me
things that don't work. Its a real issue and it requires changes in
rsync to make it work correctly.
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